10 Questions About Growing Dahlias
If you are growing dahlias this year, you may have a few questions. Though these summer-blooming bulbs are not difficult to grow, they can be puzzling. Even to gardeners with many years of experience. Read on for answers to some common questions about growing dahlias.
A healthy dahlia tuber that has already sprouted.
My dahlia never came up. What happened?
When you are planting dahlia tubers, you may or may not see a sprout. Often, the tubers don’t sprout until they have been in the ground (or in a pot) for 4 to 6 weeks. It takes tubers longer to come out of dormancy when they are planted early in the season and the weather is cool. Sprouting happens more quickly when you’re planting late and the soil is already warm.
If your tubers have been planted for more than a month and there’s still no sign of growth, it’s OK to do a little investigating. Use your fingers to very gently dig up a tuber. Take care because if there is a sprout, it’s very easy to accidentally snap it off.
If the tuber feels firm, it’s probably fine and just off to a slow start (some dahlia varieties grow more slowly than others). Carefully replant the tuber and wait a few more weeks. Should you find the tuber is soft, it may have rotted because the soil was too wet. Unfortunately this is not reversible. Dahlia tubers contain their own source of moisture and should be given little to none until they are in active growth.
Remember that no matter what sort of plants you are growing, a 100% success rate is rare. Most dahlia tubers eventually sprout, but it’s possible to get a dud without a viable eye. As long as you start with good tubers, don’t overwater, and keep slugs and snails at bay (more on that below) you can expect a 80-90% success rate. This means 1 or 2 no-gos out of 10 is relatively normal.
This dahlia is making a comeback after being mowed down by slugs.
Something ate one of my dahlias. What do you think it was?
For slugs and snails, young dahlias are a delicacy. If you know you have these pests in your garden, don’t take any chances. As soon as the sprouts begin to emerge, surround them with slug bait (use an organic option such as Sluggo). Refresh the bait weekly and after rain. Once the plants are 6” tall, the stems will be tougher and more resistant to nibbling.
Rabbits, groundhogs and deer may also munch on young dahlias. If you know your dahlias could be at risk, protect young plants with garden fabric, a scent deterrent, or a temporary fence. Should a stem get broken off or chewed, wait a couple weeks to see if the plant sends up new sprouts. They often do. You may also want to grow a few replacement plants in pots and keep them at the ready.
Here’s what a dahlia looks like 2-3 weeks after being pinched. The plant will soon have twice as many branches.
Some of my dahlias are tall and leggy. What should I do?
There are hundreds of varieties of dahlias with many different growth habits. Some are short and stocky. Others are naturally tall and lanky. Most fall somewhere in between. Though pinching your dahlias isn’t absolutely necessary, it helps to level the playing field – and most people who grow dahlias recommend it.
Dahlias should be pinched once when the plant is between 6 and 12” tall. Use your fingers or scissors to remove the center shoot just above the third set of leaves. If there are already multiple stems, you can remove all of the center shoots.
A dahlia that’s pinched produces twice as many branches from each leaf node. This gives you a stronger, bushier dahlia with more flower stems. Though pinching slows growth for about 2 weeks, the plants quickly catch up.
Dahlias can also get leggy if they are not receiving enough light. In most parts of the country, these high energy plants should be grown in full sun. If you garden in one of the central or southern states, your dahlias will appreciate some shade to help keep them cool during the hottest part of the day.
I planted my dahlias weeks ago. Why are they growing so slowly?
Knowing where a plant comes from can help you understand how to help it grow. Today’s dahlias are hybridized versions of plants that are native to mountainous regions in Mexico and Central America. At these elevations near the equator, the soil is always warm and air temperatures are constant, ranging from highs of 75°F during the day to lows of 60°F at night.
There are only a few areas in the US that offer similar growing conditions. We just have to do our best to make our dahlias happy. Most importantly, don’t plant too early. If the soil temperature is much below 65°F, dahlias grow slowly, if at all. Too much moisture also slows their growth. If you live in a cool climate with heavy soil and wet spring weather, consider growing your dahlias in raised beds filled with lighter soil. Another strategy is to plant the tubers so the eyes are no more than 2” below the soil surface. Once the plants are 12-18” tall, you can pull more soil up around the base of the plant for added support.
Even when growing conditions are good, it takes time for dahlias to find their stride. When you transplant a potted annual or perennial, the plant already has an established root system. Dahlias have tubers to support sprouting and the very first stages of growth. But then they have to create an entire root system from scratch — one that will support a 4′ plant that flowers non-stop for 3 months straight. Once your dahlias make the shift from roots to shoots, you’ll be impressed by how quickly they grow.
My dahlias are getting tall and starting to lean/bend/break. What should I do?
Depending on the varieties you are growing, some of your dahlias could get to be 4 to 5 feet tall. Because these plants have hollow stems and big flowers, breakage can be a problem — especially in wet and windy weather. The best way to avoid heartbreak is to stake your dahlias. And the best time to do it is before it’s needed.
If you have less than a dozen plants, it’s easy to support each one individually. You can use stakes and ties, a tomato cage or a cage made from concrete reinforcing wire.
With more plants, you may want to use the corral method. Insert 5’ wooden or bamboo stakes about 3 to 4 feet apart along the sides and at the ends of the bed. Use twine to connect the stakes and contain the stems. You’ll want to have several rows of twine and can crisscross from one side to the other for extra reinforcement.
Should I be watering my dahlias?
Not at first, but once your dahlias are at least a foot tall and growing strong, they usually benefit from getting about an inch of water per week. But there’s no hard and fast rule. With dahlias, too much water is worse than too little.
If the soil is sandy and the weather is hot, dahlias get very thirsty and should be watered deeply once or twice per week. But if the soil is heavy and the weather is cool and wet, you may not need to water them at all.
A dahlia’s feeder roots are very close to the soil surface. In most parts of the country, dahlias benefit from being mulched with shredded leaves or straw. This helps to protect the roots, retain soil moisture and minimize weed growth. But if you live where summers can be cool and wet, keeping the soil bare will encourage good air circulation and minimize slug and disease problems.
Do I need to fertilize my dahlias?
This depends on the fertility of your soil. Dahlias grow best in rich soil with lots of organic matter. If possible, enrich the soil with compost before you plant. Six weeks later, once the plants are in rapid growth, you can top dress with more compost or begin applying a low or no-nitrogen fertilizer.
While some people never fertilize their dahlias, others feed their plants as often as once a month. Many dahlia growers recommend using MorBloom (0-20-20), an odorless liquid concentrate made from fish and other organic ingredients.
A dahlia with tarnished plant bug damage.
I think something’s wrong with my dahlias. What could it be?
Dahlias have far fewer problems than roses, but like most plant, they can be troubled by certain pests and diseases. Common pests include earwigs, tarnished plant bugs, potato leafhoppers and spider mites. Dahlias can also suffer from several fungal diseases and viruses. We will have a new article about dahlia pests and diseases available very soon and will add the link here.
Do I need to deadhead my dahlias?
Yes! Removing spent flowers encourages dahlia plants to continue producing more buds. It also helps keep the area clean, which minimizes problems with pests and disease.
When you cut off a spent flower, don’t just snap off the head. Take time to remove the entire stem right back to a main stalk. This encourages the plant to produce longer stems and also promotes good air circulation within and around the plant.
When do I cut the flowers and how can I make them last?
Unlike tulips and daffodils, dahlias do not open up after they are cut. Flowers should be picked when they 3/4 open and before the back petals begin to soften.
Cut your dahlias early in the morning while the blossoms are cool and well hydrated. Bring a bucket of clean water out to the garden. To avoid crushing the stems, make your cuts with a sharp knife rather than scissors. As you cut, trim off the lower foliage and remove side buds that could steal water from the main flower.
Flower farmers are divided as to the best way to condition cut dahlias. Some recommend standing cut stems upright in a bucket filled with 2-3” of very hot water (165-170 degrees F). Leave them there for an hour as the water gradually cools down. The stems may get discolored, but don’t worry about it.
An equally popular technique is to submerge freshly cut dahlias up to their necks in a bucket of cool water for 1-2 hours. If you are holding cut dahlias for an event, keep the flowers cool, at 55-60°F. Colder temperatures may damage the blossoms.
Ready to learn even more about growing dahlias? Here are some additional articles available on our website:
All About Dahlias, 8 Tips for Growing Better Dahlias, Dahlia Tubers: What You Need to Know, How to Grow Dinnerplate Dahlias, How to Grow Border Dahlias, Tips for Growing Dahlias in Hot Weather, How to Pinch and Stake Dahlias, How to Overwinter Dahlias, and Dahlia Flower Types and Sizes
Great artical, awsome information. Thanks Cflowers
Hi Chris – Great! Thank you for leaving a comment. 🙂
I have been lifting Dayhlia tubers in winter but this year will leave them in ground as the climate has changed what do you think ? Live in Essex SE.
Hi Janet – with warming temperatures, more gardeners are finding their dahlias can survive the winter outdoors. If the temperature doesn’t get cold enough to freeze the tubers and the soil stays dry enough to keep them from rotting, you should be fine. No guarantees when it comes to gardening!
Great info. Thx
Thanks, Alan!
My dahlias had one beautiful bloom on each plant. Once I cut it down as it withered I hoped more would bloom. The plant still looks great and healthy but 3 weeks later no more blooms. Should they have bloomed more than one flower each?
Hi Christina – It takes a couple months for dahlias to develop their root systems. As the plants get bigger and stronger, they will be able to give you lots of flowers, continuously all the way into early fall. To produce that first bloom takes lots of energy and sets the plant back a bit. For this reason, many gardeners cut off the first couple buds. This forces the plant to concentrate its energy on continuing to develop the roots and foliage. But that is hard to do when you are eager to see the flowers. At this point you just need to be patient as more blooms will come. Water and fertilize as needed. Enjoy the flowers!
I can not get my dahlia to bloom. The plant looks good and I pinched it back. This is the 2nd year I’ve had it. It didn’t bloom the 1st year either. It’s planted in a pot. Any ideas why it won’t produce flowers. Zone 6. TIA
Hi Yvonne – I don’t know why this plant won’t bloom. Is it growing in full sun? Is the pot large enough for the root ball?
I only give my plants a couple chances to perform. If your dahlia doesn’t bloom this year, I suggest starting fresh with a different plant next spring.
[…] #2 Healthy dahlias are naturally much more resistant to pests and disease. For best results, pamper your dahlias as you would a prized tomato plant. Learn about caring for them here: All About Dahlias, 8 Tips for Growing Better Dahlias, and 10 Questions About Growing Dahlias. […]
I’ve planted several dahlias and they are growing so well..the problem is I didn’t realize I needed to have any support for them before planting! I’m new to this. Now I’m trying to play catch up and get them supported correctly without hurting the plant/blooms. Any last minute suggestions? I keep having to add another post and more tying every week…. They are getting SO tall and really pretty, I don’t want to mess it up! 🙂 I should also add, they are in an area at my house that is very visible, so I would rather not do something that will be an eye sore.
Hi Page – Staking and tying is your only option at this point. You’ll get to know your dahlias very well! Have you tried using bamboo? It’s available in many different heights and thicknesses. If you are staking as you go along, it’s nice to have choices. I think the bamboo also blends in better than wood stakes – especially after the first year and it’s weathered a bit.
I have Voles, Meadow mice eating my dahlias. Apps. 15 out of 20. Any suggestions?
Hi Bridget – This was the first year I lost dahlias to voles. The plants were about a foot tall and looking good, then one day toppled over. I dug them up and the tubers had been eaten. Where I live, it’s been the worst rodent year in memory. Voles, mice, chipmunks and rabbits. We trapped dozens of them. Hopefully it was just a population surge and next year we will be back to more normal numbers. I have read about dahlia growers who keep their plants in pots — just dig a hole and plant the whole pot. Have not tried it myself, but that would probably protect the tubers. Good luck!
Thanks for this great article. I’m going to get better at growing dahlias each year. I’m looking forward to ordering more tubers as soon as they’re available. When will that be? My dinner plate dahlias inside my green house at 7,000’ in New Mexico are getting brown edges on their leaves. Some leaves turn yellowish green too or spotted. Even though I have two big fans and one medium fan, it can get up to 105 degrees on a hot summer day, then fall to 60 at night. Often I need to water every day if it’s really hot or they wilt. But I see it says here that they don’t like to be over watered. I’m having similar problems with my hibiscus even though it produces lots of flowers. And I’ve had fruit drop on my fig trees. I’m wondering about spider mites too as occasionally the dahlia bud seems malformed or brown. Any suggestions? Thank you.
Hi Diane – You are doing the right thing. Just try to get your plants through these very hot days and they will be happier as it begins to cool down. Unfortunately, spider mites like heat and dry air.
We start taking orders for dahlias in December for shipping March-May.
Hi, my Dalias are in pots and I haven’t changed the pots they are in for two years. Could this be the reason they aren’t budding? And if so what is your recommendation for repotting? I live in CT so they come inside for the winter, go dormant and then I start to water again in March, FYI. TIA!
Hi Mindy – Overcrowding could be the reason your dahlias are not producing flowers. I overwinter dahlia tubers as well, but always divide them in the spring. Try doing that next spring – divide the clumps in half or thirds and repot in fresh soil. That said, there are other things that can cause dahlias to be stunted or not flower. Where I live, my dahlias have been affected by this year’s early summer heat and drought. It’s early August now and about half of them have yet to bloom, which is very unusual. But recent rain and cooler weather has transformed them. Now they are growing quickly, have healthy foliage and lots more buds are coming. Dahlias are so rewarding when they bloom and so confounding when they don’t. Good luck!
Today, 21/08/2020, I saw a mouse eating the flower petal of a fully grown dahlia. Closer examination of other dahlias in the raised bed revealed mouse droppings on three other dahlia blooms.
Hi – That’s a new one. Mice, chipmunks and other rodents are having a banner year.
Some of my dahlias are stunted with curly, puckered leaves. They have been in this state for a number of weeks since they got about 18″ high. I sprayed them a couple of days ago with Sevin thinking that they have been attacked by aphids. It is too early to know it it worked. Is there any other disease or pest that would cause this condition?
Hi Nicholas – This does not sound like pest damage. More likely it is disease or stress. We have a recent blog post about dahlia diseases: Common Dahlia Pests and Diseases. You don’t say where you are located, but this year many gardeners on the east coast are reporting that some of their plants are stunted and not flowering. Dahlias hate weather extremes (some varieties more than others) and unfortunately, when they get stressed early in the growing season sometimes they are unable to recover. Hopefully the majority of your plants are thriving. Best of luck
Many of my dahlias have yellowing leaves. Web sites recommend lots of organic material so this year I mixed dehydrated cow manure (1 part per two parts of original soil) when I planted the tubers. One website suggested sulphur to lower pH which I did a month ago then this week and iron chelate. I sprinkled Espoma Iron Tone around each plant. I don’t think my dahlias are as good this year as in previous seasons. The same is true for my vegetables. Lots of aphids, thrips and various fungus and virus diseases which I never had before.
Some years are better for dahlias than others. But since you are having problems with other plants as well, here are some suggestions. Dehydrated cow manure is more concentrated than regular composted manure. The amount you applied is much more than I would recommend. This may have stressed the plants – especially when first getting started. Also, always do a soil pH test before trying to raise or lower the pH of your soil. Too much in either direction causes problems with nutrient uptake.
Hello,
I planted dahlias for the first time this summer. I live in northwest Georgia and our summers are very hot. They did pretty well other than laying down, however, I did not stake them and upon reading your suggestions, I should have maybe pinched them back. Note, that our soil is clay.
My question is, do I need to dig up the tubers since the ground here doesn’t really freeze in winter. We may get snow once a year, but it quickly melts. Temps may go below freezing but it might just be a few days out of the winter.
I would really like to plant more for cutting next summer. They did well except for them laying down and splaying outward. thank you,
Hi Laurie – It looks like you live in growing zone 7, so your dahlia tubers should be able to survive – except in very cold winters. Unfortunately, clay soil can make it more difficult because the tubers can rot if the soil stays too wet. That said, I would give it a try!
How do we protect against gophers?
Hi – Unfortunately, gophers and voles love to munch on dahlia tubers. Sometimes cats and dogs can be effective vole and gopher killers. You can also try planting the tubers into wire cages made from hardware cloth. Though this material is heavy and can be hard to work with, you need the 1/2″ mesh to keep the voles out. This article on our website may give you some other ideas: How to Protect Flower Bulbs from Voles.
Why have my dahlia bulbs risen above the soil? Should I cover them up?
Hi Fiona – It will not hurt the plant to have some of the tubers showing above the soil surface. But hilling up some soil (5-6″ deep) around the base of the plant will help keep the root area moist and also give the plant some additional support. Dahlia stems are hollow and more likely to break when they are planted shallowly. If you are concerned about that you can add some stakes and tie in the large branches.
I have a bed that I am preparing for dalias in zone 6, it is 5’x10’. How many plants should I plan on purchasing? Can I plant daffodils bulbs with them to help control pests. Thank-you.
Hi Susan – Depending on the dahlia’s mature size (it varies from one variety to another) we recommend spacing the plants 15-18″ apart on center. Sorry, but daffodils do not control pests.
So my dahlia plants finally hit 12 inches but it’s now October 21st, no blooms still. The plant is beautiful, green and lush, no blight just no blooms. We are expecting a frost here in Seattle Wa area this weekend, do I cover? Do I cut back & leave tuber for next year? Do I dig up tuber? I planted 3 tubers two came up like described above, 1 is a stunted joke. Very bummed at my first try!
Hi Michele, it’s been a pretty terrible year for dahlias — for me, the worst in 15 years. Several varieties that I have grown for many years (from saved tubers) didn’t put out a single flower. Some plants performed normally, many plants grew well but failed to bloom, and other plants were about 25% of the height they should have been. Gardeners and flower farmers on the east coast as well as in the southwest and northwest have experienced the same thing. Where I live, we suspect it was excessive heat in June followed by 2 months of little to no rain. But other areas had different weather and similar problems. If you want to save the tubers, let the plants get frosted and then dig them 1-2 weeks later (information about digging and overwintering is on our website). I decided to toss the plants that didn’t perform and kept the ones that did. Hopefully we will all have better luck next year!
I love these flowers i do dinner stes and this was very helpful .
Hi. I live in Sunny Sri Lanka. I panted several Dahlia tubers and after 7 months, only one plant bore a few buds and they all dried off. They get plenty of sunlight so that’s not a problem. Now that same plant has about 3 buds but they don’t seem to be blooming either. I use k44 spray once a week plua composite. We have purple granular fertilizer over her which is best for flowering. (High K). In simple terms, what should I do? 🤔
Hi – Are other people in your area successfully growing dahlias? Their native habitat is cool mountain highlands where there is lots of sun, but temperatures do not rise much above 80°F or go lower than about 60°F. If the temperature range is suitable, how about moisture? Dahlias perform best when they get consistent moisture at the root zone. Not wet (or the tubers will rot and not grow), but they will not tolerate drought conditions. They also do not need a lot of fertilizer, so don’t overdo it. Best I can recommend is to continue experimenting to see if you can find the combination of conditions that make them happy.
I have grown Dahlias for many years with great success. My question is, what do you do for powdery mildew . Its common in coastal areas. I’m in southern California 5 miles from coast. I have used many products. But alot have been taken off the market. The best one was Bayelon by Monerey nursery. I have tried some of the oils. But sometimes they burn when weather is 80 and above.
Hi Leah – It’s true that many fungicides are off the market now due to toxicity. For home gardeners, most of our remaining options are defensive. Do everything possible to keep the foliage dry. Fungal spores can’t enter leaf tissues unless the surfaces are moist for a length of time. Always water at the root zone. Allow lots of space between plants to encourage good air circulation. Once the plants are relatively mature, you can prune off some of the foliage at the bottom of the plant. Deadhead every couple days and remove any damaged branches or leaves. Alway keep the area around the plants as clean (of organic debris) as possible. The American Dahlia Society has an article on Fungus Control for Dahlias. Hope this helps!
Las dalias pueden cojer sol o son de sombra. Gracias.
Hola Blanca – Las dalias necesitan sol todo el día para florecer.
Can we keep dahlia plant the same pot for off season. I mean it is necessary to remove tuber and store it for next season. What if i keep the plant as it is for next season.
As it is already mid March and i guess we can grow tuber in late June. So it is just 3.5 months. Do i really need to remove tuber and dry and store?
Please answer
Hi – sorry for the delay in responding. You can store the tubers right in the pot. Just don’t water the soil while the tubers are dormant. The two biggest risks for overwintering dahlia tubers is freezing and too much moisture. Hope you have good results. It sometimes takes a couple tries to figure out the best way to overwinter tubers. So much depends on your climate and storage conditions. Good luck!
It’s first time for me growing dahlias. They seem to have a small flower heads. Will the heads get bigger next year or did I buy a small flower variety?
Hi – Sometimes the first few flowers can be a little bit smaller than normal. With dahlias, flower size is particular to the variety. For example, Cafe au Lait flowers will always be 6-8″ across. The size of Boom Boom Yellow’s flowers will always be about 3″ across. This does not change from one year to the next. Check which variety you purchased and that should tell you what size flowers to expect.
Hi there
I live in Vancouver Canada. This is my first time growing Dalias… now that my tubers, that I have started in pots before I transfer into the garden, have started to show shoots, do I begin to water and place the pots outside in the sun? I was going to wait till they were 6 inches high before transferring them to the garden
Thank you
Hi Connie – yes! give them some water as needed, plenty of sun and protect them from frost. Transplanting at 6″ tall or so works well for me.
Hi, I’m just getting my dahlias out from winter storage. Many have sprouted already and I’ve read that I can trim the sprouts back? Do you recommend? Also some are sprouting from last year’s wood. Will those be viable or do they need to come directly from the tuber? Thanks!
Hi Hazel – dahlia sprouts emerge from the stem tissue, not from the tubers themselves. So what you are seeing is normal. I don’t trim the sprouts back myself, but I don’t think it would harm the plants. You could also wait and pinch the plants once they get to be about 8″ tall.
I love my dahlias and do have fun with them now that I’m retired. I learn something each year about how to keep them beautiful. Your articles were a great source of information. Thank you
Thanks, Luann! What a good way to fill some of your retirement hours.
Hi there! I’m in Pennsylvania, and this will be my first year giving dahlias a try. I plan on putting them in pots. I’m pretty sure it depends on the size of the pot, but how many should I put in a pot? Also, do you recommend dedicating the pot solely to the dahlias or mixing in other fillers, etc? Thank you so much!
Hi Kristen – In this article (at the bottom) there is a chart with recommended (minimum) pot sizes for various summer-blooming bulbs: How to Grow Summer Bulbs in Containers. With border dahlias, it’s OK to plant a couple tubers in each pot. With all other types, we recommend just one clump per pot. Dahlias are hungry and thirsty plants — they don’t like competition. If they’re happy, they will dominate any other plant, so it’s best to give them each their own container. If you want something to look at while the plants are getting established, you could plant some cool climate annuals (pansies or sweet alyssum) and then remove them as the dahlias start to fill in. Hope this helps!
My dahlia tubers have a couple inch long white sprout (not green). Do I put the white sprout under OR above ground?
Hi Gino – position the tuber so the place where the sprout emerges from the tuber is about 2″ under the ground. If that winds up covering up the sprout, don’t worry as it will continue to grow. If the sprout is exposed, you may want to shield the top of the pot from direct sunlight for a couple days to let the sprout adjust to more light.
Thank you Kath
Maybe that last question applies here – my tuber was already sprouted when I planted it, but we had a hot day and it seems the top burned. Do you think the tubers will send up more shoots, or will those sprouts rejuvenate?
Hi Rebecca – I think you should just give it a couple weeks. Dahlias have a lot of growing power and I bet that plant will come back with more shoots. Hope so!
Hi..I planted my tubers about 8 wks ago and there only some that are about 8” tall… and a few others even shorter…. they’re growing really really slow? I wanted them nightly at the same time and I fertilized them about two weeks ago….. I don’t know what else to do? Help! I live in Central Florida
Hi – With dahlias, too much moisture, especially when the plants are still young, can inhibit growth. So you may be overwatering them. But you will also find that dahlias are quite difficult to grow in Florida because of the heat. They prefer cool nights and daytime temperatures that don’t get higher than the low 80’s. It is possible to be successful, but the plants need to flower before it gets too hot, which means planting the tubers in Feb/Mar. Another option is to plant the tubers in the fall (if you have access to them at that time of year).
What about pre grown dahlias? I have one I bought as an already good sized dahlia, it bloomed a beautiful scarlet red with white tips but since I cleared the dead head it has not bloomed again! Could it be the size of the pot holding it back? Last year the same thing happened and I think the squirrels were eating the new buds off and that was why it hadn’t bloomed, but this year I kept it inside near a window- away from the squirrels and it still isn’t blooming! Help!
Hi – Dahlias require at least 6 hours of direct sunlight each day in order to have the necessary energy to produce flowers. They are not indoor plants, nor will they bloom in the shade. Though dahlias will grow in a container, most of them (other than border types) reach a mature height of at least 3′ tall and need a large pot — best if it’s 18″ x 18″. Hopefully you can find a sunny place to put this plant — or offer it up to a friend who has a sunny spot and will share some flowers with you.
I bought an expensive selection of tubers and planted them in late March. We have had a lot of rain in SE England this May. Not one of the tubers has grown. Should I still hope they will?
Hi – Plants that grow from bulbs, tubers, corms and other such storage vessels can have a hard time getting started in cool, wet soil. If I were you, I would dig up some of the tubers and check on them. If they are soft, it’s likely they have rotted. If they are firm and you see some sprouts, put them back and be patient. Hopefully next spring will not be so wet. To avoid problems in the future, consider starting these plants in pots and then transplanting them into the garden once they are in active growth.
Hi, I live in Hertfordshire and planted lots of new Dahlia plants only to have had them totally desecrated by slugs. I even used slug pellets but they still eat them. Some of the smaller plants have disappeared altogether, the taller plants have had their flowers eaten but the stems still appear to be ok. Will these dahlias come back? or do I need to lift them? or have I lost them for good?
Thank you
Hi Bernice – Sorry to hear you are fighting slugs. They can cause so much damage, especially to young dahlia plants. I have noticed that some years the problem is much worse than others, probably due to weather as well as population booms. Though losing buds and foliage does set the plants back, they can usually recover. Even dahlias that have been eaten to the ground will often re-sprout and survive. Keep it up with the slug pellets (I spread them twice a week when we are in a rainy period.) I now use slug pellets that contain spinosad, which also kills earwigs. Good luck!
Hello- is it possible the color changes after season? i planted the bulbs stating yellow colors and for the last two seasons it bloomed that color, but now (july) buds and flowering the colors are red/burgandy. I kept the bulbs in the ground did not dig to store during winter. Is that possible?
Hi Lorna – Yes, this does seem to happen. Tubers that produced flowers in one color can shift and begin blooming in an entirely different color.
My dahlias were growing great, then suddenly several started wilting and flopping. I dug up two and found mushy tubers. I have clay soil amended with compost, but I think the soil is still too heavy. Should I dig up the remaining plants and place them in grow bags? It’s hot here too, so that adds to the trouble.
Hi Amber – Dahlias do hate soggy soil. It’s hard to move the plants once they are growing as the connection between the stems and the tubers is fragile. But give it a try! Growing them in grow bags is a good idea.
We have about a dozen Dahlianova Carolina Orange and Carolina Burgandy (8″-10″ border plants). They have filled out beautifully and all have a good number of blooms, but the stems on the flowers are VERY short and mostly buried within the leaves. About half are in containers, the rest are in the ground, all have this same growth pattern.
Is there something I can/should do to thin out the leaves so we can see the flowers better?
I deadhead often, daily if needed, sometimes there are buds that turn brown/wilt before they even open. We are in Zone 6a. Thank you in advance for any suggestions.
Hi Dawn – I have never grown Dahlianova dahlias, but I am pretty sure they are bred to be short. They are meant for bedding and containers, not for cutting. We sell a similar type and call them “border dahlias”. If you want to grow dahlias that produce longer stems, you’ll need to plant a variety that grows at least 30″ tall. This includes most decorative types, singles and doubles. You can learn more about the various types of dahlias on our website and on this infographic: Dahlia Flower Types and Sizes.
Missing questions: How do I store my dahlia bulbs over winter? Why did my dahlia bulbs shrivel and die over the winter inside?
Hi – We have an article about that on our website: How to Overwinter Dahlias.
very helpful information. answered all my questions i wanted answered. Happy i signed up for this blog. thank you
Hi Robert – Glad to have you along!
I planted my dahlia this year some bloomed one and one and the others didn’t what could have happened!
Thank you, patmac
Hi Pat – Dahlias have a mind of their own. Some are quicker and more eager to bloom than others. Hopefully you will still get some flowers later this summer. Each year I have a plant or two that doesn’t bloom. Never sure why!
Hi there, i have had a virus in my dahlias this year and I’m digging them up to throw out but wondered, it it obvious by looking at the tuber that the plant has a virus? They look really healthy and i was just curious to know if it showed up in some way in the tuber or if the tuber remains unaffected looking. It has a terrible effect on the leaves and flowers!
Thanks, Karen R
Hi Karen – Unfortunately, it’s impossible to tell from the appearance of the tubers. Even young plants can look perfectly fine until the virus starts to get the upper hand. When pathology labs test for dahlia viruses, they test the foliage rather than the tubers. Last summer some of my dahlias had indications of virus — stunted growth, yellowed foliage, distorted stems, few buds. So I destroyed all the tubers and started over. Thankfully, this year’s dahlias look great. Good luck!
Hello,
This is Disha. I bought potted dahlia from Costco last month while it had one blooming flower which was almost dried and several buds. I have been regularly watering the plant and even added a fertilizer 2 weeks back but I don’t see the buds opening. A couple of them started opening but with dried flower leaves. The plant has lush green leaves and about 20 new buds. I don’t see any signs of infection in the stems or leaves. I have kept the potted plant in a shade as well so that it doesn’t gets the direct afternoon harsh sunlight. I don’t understand what is wrong with the plant. Can you please help?
Thank you,
Disha.
Hi – Make sure your dahlia is getting enough light. It is good to shade it from excess heat, but the plant should get a minimum of 6 hours of direct sunlight each day. When the air temperature is hot, dahlias will often refuse to bloom. As fall approaches and the weather begins to cool down (especially the nights) the plants should start blooming again.
Hi there – I planted several tubers this year and only have a few that came up as plants (no blooms yet). Is it worth it to dig up the tubers and try to overwinter them for next season (I have a general idea where they are in the bed, even though they’ve not sprouted).? Or are the ones that didn’t grow considered duds and not worth trying to save for next season? I’m in Michigan with harsh winters and its been a hot, pretty rainy summer – yet our local dahlia farm is doing fabulous with their blooms this year already.
Hi Michelle – If the tubers didn’t sprout, they may not have had eyes. They also could have been too dried out or too soft, or the growing conditions were just not agreeable. Definitely not worth trying to dig and save. Dahlias like consistent moisture but do not like wet soil. They also dislike hot weather and do best with cool nights in the 60’s or low 70’s. It can take some trial and error to have great success with dahlias. Results can also vary from one year to the next. Give them another try next year, making sure you start with quality tubers and treat them like tomatoes (good soil, full sun, consistent water and fertilizer). Good luck!
Thank you so much for the reply. I’ll get some new tubers for sure, and try again! I had great success last year in the same bed. So strange, but our weather this spring was pretty different.
This article is very useful for an amateur gardener like me, thank you!
Hi, it is now the end of summer.. How can I save dahlia bulbs over the winter that did not get planted ? Will the bulb have energy for next spring?
Hi – It’s very unlikely the tubers will still have viable eyes (sprouts) next spring. That said, dahlias are full of surprises. You could save them in a cool place and see if they sprout next spring.
Thanks for a great article. I have some Dahlias that have come up and are healthy looking plants but still no flowers I know some are late to the party and here in Northern Michigan I’m always afraid I’ll get a frost before they do. I don’t have a lot of areas that have long periods of full sun so I’m sure this is the reason they are delayed. If this happens can I dig up those tubers and try again next year?
Yes you can. As long as the plants are healthy, the tubers should also be healthy and worth saving. It doesn’t matter if they bloomed or not. In my experience, dahlias are incredibly sensitive to weather and therefore perform differently each year. I had very few flowers last summer, but lots this summer. Good luck!
Ive checked around and do not see an answer to my question. My dahlias are growing great, too great! I have 13 sprouts from one group. I’ve heard to cut all but 3-4 stalks off the base, this is said to promote stronger albeit less stalks and blooms. Does this make sense to you? thx
Hi Jim – There are many different points of view on the topic of pruning dahlias, and each variety has a slightly different growth habit so results will vary from one variety to the next. I am of the live and let live school and do not prune out any of the stalks. Since I live in a windy area, I prefer bushier plants with more stems. You could try pruning a couple plants and see what you think about the results. Also be aware that a tight cluster of 13 sprouts could indicate a bacterial dahlia disease called leafy gall. Check this article on our website to be sure that’s not what’s happening: Common Dahlia Pests and Diseases.
Thank you for this article. I have lost about 50 percent of the dahlias I planted and I grow quite a few. I believe that it has not been long enough to have them sprout. I wouldn’t have thought that was the issue but reading this article helped.
Hi Mary – Dahlias can be heartbreakers. Every year is different. Not sure one lifetime is enough to figure them out!
I purchased many dahlia tubers because they were half price for the season. i want to plant then NEXT year. At another home that is not ready yet. can I store them and plant next spring or will they not grow if the tubers stay out of the ground more than a year. And If I can do this is there a way to store them better than the plastic packages they are in …just from Lowe’s garden center.
Hi – Sorry to say you cannot store the tubers for that long. They need to be planted this year. As a gardener I have learned to never say never, but it’s highly unlikely they will sprout after being out of the ground for 18 months.
I bought a bunch of dahlias from Longfield gardens, planted them in very large planter boxes with brand new soil, but now have indications that they are all infected with mosaic virus. They have no insect pests that I can see, so nothing that should have introduced the disease. Do any growers guarantee tubers that are disease free?
Hi Claire – I have not seen any suppliers that guarantee disease free tubers. The only way to make sure a tuber does not contain any virus is to test it in a lab. It can be very difficult to diagnose disease problems in dahlias. Weather stress can cause similar symptoms. Dahlias are also vulnerable to bacterial diseases, which are often passed by insects. You may find this article helpful: Common Dahlia Pests and Diseases.
I planted a dahlia that came up with two stalks. I didn’t; pinch the second one off and now that it is bloom time this neither of the stalks have bloom heads. Any suggestions on how to force bloom at this point?
Hi – It is unlikely that the central stalk with produce a flower on top. You need to encourage some side branches. It is late in the season to do this, but you could try cutting off the top of the stalk. This may help to focus energy on producing side branches below that point. If the stalks are large, cut when the weather is dry so the plant has time to seal the hollow stem before it gets filled with rain.
I bought a Fairway Spur Dahlia, foliage is great, lots of blooms but so far every single one has been distorted. Are the tubers infected? Are they worth overwintering or will it be the same next season? I have 5 other Dahlias all in pots, this is the only one with the problem.
Hi Jillian – Sorry to hear that your Fairway Spur dahlias are not performing well. If the foliage looks great and the plant is producing lots of flowers, it’s unlikely they are diseased. Dahlias are naturally variable and can misbehave, which you can learn about in this article. I don’t recommend overwintering those tubers. Please contact our customer service department so we can issue a refund or send you replacement tubers next spring.