By Anita B. Stone – For years I have tried my best to grow plants in containers because of the limited space in my garden and also because I can move them around, depending on where the sun and shade are prevalent. After a decade of learning how to take care of plants in pots, I have picked up some good tips. There are ways to create luscious blooms and plants that thrive in their own “home.”
My plants have experienced container-plant death from overwatering. I am more diligent not to let them dry out, by lessening the obsessive water technology. Plants benefit by allowing oxygen to pass into the soil when they become dry. The idea is not to encourage suffocation. The top of the soil is not a true indicator of whether or not the soil is dry or wet. Using a popsicle stick or your longest finger up to the second knuckle, check out the lower area of each plant. Another true test is to look closely at the roots. If they appear black or whitish and mushy, then rot is evident. I’ve always scheduled water and feeding times in the early morning or evening, avoiding the heat of the day. As an added measure I have stopped using overhead sprinklers because they splash, often leaving water droplets on top of the foliage, which encourages disease problems. Attempting to keep the leaves dry and the soil slightly dry is the ticket to proper water management. Recently I designed a plan to place soaker hoses inside the rim of my containers. This control offers just the right amount of water when planning my schedule.
Plants have different water requirements. If you grow cactus or other succulents, be vigilant with water because these plants love dry soil or natural moisture (dew). You can purchase a moisture meter to measure proper levels within the soil. Soil provides a good balance between water-holding capacity and aeration. People are always searching for the best potting soil. I usually use a soil-less mix which I find in bags marked “container mix.” These mixes offer water retaining granules that perform well in containers. For cactus and plants that require low amounts of moisture, try adding a bit of sand for better drainage.
I have often been guilty of not putting enough soil inside the container. One trick I learned is to use filler material to help prevent root rot. Filler can be any type of packaging, such as Styrofoam “peanuts,” clay pot shards, or even newspaper. The filler adds drainage and helps prevent rot. Nowadays I put the soil level up to about one inch from the rim of the container. Once plants are in the container, make sure to add more soil if any roots are exposed.
Whether in-ground or placed in containers, all plants require light to survive. Light ranges from full sun to complete shade. I learned that the most common cause of lack of blooms is not enough or improper light. Frequently the greenery shines with growth but flowers do not appear. Part-sun or medium light plants do best with approximately four hours of direct morning sun. Petunias, zinnias, and pansies need six hours of sun daily. Growing vegetables in pots means those veggies will require six to eight hours of sun daily. If you’ve been wondering which winter vegetables to grow this season, keep in mind that even winter vegetables require the proper amount of light for healthy growth.
One neglected area that I became aware of was that container plants require food more often than plants in the garden. After the first blooms appear on plants, feed them again with slow-release granules. Avoid feeding plants when the soil is dry because you can burn the roots. It is preferable to water first prior to feeding. I find that feeding foliage plants monthly worked well during their growth periods. But the blooming plants required feeding more often because they need more energy, so my feeding schedule became once every two weeks while flowers were blooming. September is a good month to let up on feeding container plants that I wanted to overwinter.
Believe it or not, plants can become stunted if your container is too small to accommodate their width and height. Not only does size and type of plant “home” matter, but make sure the plant receives the proper environment. Too often I have planted small roses in pots that were too big, hoping the plant would fill it out, or I have planted an overwhelming number of bulbs in a pot without the knowledge that the bulbs should not touch each other inside the container. Most annuals have shallow root systems, so they will function in containers that are wider than they are deep. I often fill the bottom half with filler. My rule-of-thumb is to use a container approximately three inches larger than the roots of the plant. This keeps the plant from “drowning” in too much soil and water. Whatever type of pot you use, make sure drainage holes exist at the bottom. I learned that the hard way when my bean plants suffocated from lack of air and drainage.
Having an answer to “what planting zone am I in? is important because often I have purchased plants that do not winter over and survive until the next season. But cold isn’t the only factor that determines whether plants will survive. Too much heat also makes an impact and will kill a plant instantly. The AHS (American Horticulture Society) Heat Zone Map is used the same way that the Planting Zone Hardiness Map is used. Zones range from 1 (north) to 12 (south), which indicate how many heat days occur each year, and helped me figure out which plants would grow best in my containers.
Upkeep is a necessity. Maintenance is keeping any container plant looking nice by deadheading dying flowers and clipping old, dead stems and foliage. Paying attention and offering TLC keeps my plants from withering, going to seed and encourages more blooms. Keep a lookout for insect damage also. Use horticultural oil for an organic method of keeping the environment clean and free of pests while eliminating pathogens. Make sure you can identify the insect prior to treatment. If unsure, collect the damage in baggies and head for your local nursery or the Agricultural Extension Agent in your area for identification. For the short term, I simply give insects a strong shot of hose water. Over the past few years, I have noticed an accumulation of white-looking grit around the inside of my containers, especially perennials. I have carefully removed the rootball and wiped off the “salty” appearance using a solution of water and bleach. Once dry, I add fresh soil, then replant.
Make certain to consider location, a major part of container success. Check out the sun and shade stats for any plants prior to placing them in a container. The smallest amount of sun that shines on a shade plant is unhealthy for the plant. Sun-loving plants do not thrive well in shade, especially under trees. Just because a plant offers beauty doesn’t mean it is container worthy. So treat the plant with respect and dignity, allowing it time to grow and bloom. Once I discovered companion plants and how they function, I was able to create and design some awesome combinations within the same pot or areas.
Ancestry is important to the growth of a plant. If you plant johnny-jump-ups you can be certain it will thrive in part sun, moist, soil-rich conditions as it has for decades. Native environment is important for plants. I prefer ornamental grasses, so I know each prefers a dry area and well-drained soil. Familiarity assists with plant growth. Many books have been written about the right plant for the right place, so it’s a good idea to bone up on the information to avoid failures, diseases and unnecessary aggravation.
When I remind myself that plants, like people, need a healthy environment, then I am fully in charge of making sure they grow, thrive and offer top-quality performance.
I hope this tutorial offers you valuable guidance on how to take care of plants in pots. Would you add any tips to the list?
Originally published in Countryside May / June 2014 and regularly vetted for accuracy.