How to Keep Container Plants Looking Their Best
It’s the merry month of May and at this time of year, gardeners everywhere are busy buying plants and stuffing them into pots of all shapes and sizes. Shopping for container plants is one of my favorite rites of spring. I love all of it: selecting the plants and the pots, composing the designs, and seeing my unique creations come together.
Today’s garden centers are packed with such a wide selection of beautiful, well-grown plants that it’s relatively easy to compose a great-looking container. What’s far more challenging is keeping your pots and planters looking good for the next five months.
Here are seven ways to help your container plantings stay lush and healthy all season long.
Start With the Right Size Pot
Plant size should determine pot size. As a general rule, think about how much space the plants will occupy at the end of the season and use a pot that’s at least half that size. Bigger pots allow plants to grow unrestricted. They also hold more soil and moisture, which means you can water a little less often. Do make sure that your containers have drainage holes so the roots can breathe and excess water can drain away.
Choose Container Plants that are Compatible with Your Yard… and with Each Other
When shopping for container plants, it’s easy to fall in love with attractive, but unsuitable candidates. Go ahead and put them on your cart. But before you get to the register, pull over and try your best to be rational. Stick with plants that will be happy with the light conditions in your yard, and the amount of space and attention you are willing to provide. Leave behind those plants that are bound to struggle once they come home with you.
While we are accustomed to seeing container plantings that include several different types of plants (thriller, filler and spiller), in reality, most plants grow best in a pot on their own. This way, they can grow at their own pace and don’t have to compete for light, space or moisture. It’s a planting style that’s used to great effect at England’s famous Great Dixter House and Gardens, which you can read about HERE.
If you do combine more than one type of plant in a container, make sure they have similar light and moisture requirements. Some plants need moist soil, while others actually prefer being on the dry side. Full sun is required by many, though some prefer full or part shade.
Plants also grow at different rates. Summer bulbs such as dahlias, cannas and eucomis are slow out of the gate, but once they hit their stride in late summer, they can completely dominate other plants.
Elevate Your Containers with Foliage Plants
Some of the most impressive container plants never produce a single flower. Examples include elephant ears, ornamental grasses, bamboo, caladiums, Persian shield, coleus, sweet potato vine, helichrysum, ferns, eucalyptus, euphorbia, croton and phormium.
Rather than putting energy into making flowers, foliage plants can concentrate on what they do best — growing leaves! Big plants with interesting foliage textures and leaf colors help to unify a planting scheme and will give your whole display a bigger presence.
Use a Quality Growing Mix
The soil in your containers should be light, loose, well drained and moisture-retentive. Don’t try to use garden soil as it will quickly become compacted by frequent watering. Instead, use a high-quality, soil-less growing mix that’s made from a blend of sphagnum moss and vermiculite or perlite.
Some of these growing mixes are more coarse than others. For containers, a relatively coarse mix is best (and will also be the least expensive option). If you are filling large containers — or have many of them, you can save money by purchasing container mix in a 3 cubic foot bale.
For best results, dump last year’s soil into your garden and fill the pots with fresh soil each season. If this is cost-prohibitive, remove the top half of the soil, break up what remains and then fill the rest of the pot with fresh soil.
To enhance the growing medium, mix in some finished compost. This will improve the texture, increase the moisture-holding capacity and add nutrients. Aim for about 20% compost and 80% growing mix. Always moisten the mix with warm water before planting.
In most climates, container-grown plants require almost daily watering. Take time to water slowly and deeply at least twice a week to ensure all the soil in the container gets thoroughly moistened. This will encourage plant roots to grow downward rather than clustering near the surface.
Consistent watering reduces plant stress and helps to promote good health. When the soil gets too dry, delicate feeder roots can die back. Replacing those damaged roots requires plants to expend energy that would normally go into leaf and flower production.
Frequent watering flushes nutrients out of the soil. So even if you start out with a premium growing mix that’s been fortified with granular fertilizer or compost, there may not be enough nutrients to sustain the plants for more than a month or two.
To make sure your container plants don’t go hungry, consider applying a time-release fertilizer such as Osmocote. These water-soluble granules feed plants for 4 to 6 weeks, depending on how often you water and/or how much it rains. Follow application instructions on the label.
Alternatively, you can use a water-soluble fertilizer (such as Miracle-Gro or Shultz) or a water soluble organic fertilizer with fish emulsion (such as MorBloom or Maxicrop). Apply every 2 weeks from May through September.
Primp, Prune and Replace as Needed
Once a month or so, plan to spend a little grooming time with your containers. Remove spent flowers and cut back leggy stems. In late summer, consider replacing stressed or tired plants with fresh ones from a local garden center (or your own garden). Ornamental kale, asters, sedums and mums will give the containers an updated look that’s perfect for the season ahead.
With just a little extra effort, your pots and planters will have what it takes to maintain their good looks all summer long.
To shop our complete selection of summer-blooming bulbs for containers, click HERE.