Because plants in containers can’t stretch their roots out to get water and nutrients from the surrounding soil, and because the roots are generally not as insulated from temperature extremes, there are some care requirements specific to container gardening.
Watering Container Plants
Watering is key. Plants in containers need to be watered more often than plants in the ground. This is especially true for hanging containers, those with lightweight soil mixes, and all containers during hot weather.
Water container plants gently, using a watering can with a gentle flow, or a sprayer or watering wand attached to a garden hose. Soak the soil completely. Empty any saucer below the pot as soon as possible, and never let water stand for more than 24 hours. If it’s hard to get the saucer out, use a turkey baster to remove the water. Also remember that even self-watering planters will need to have their reservoirs filled with water periodically.
Drip irrigation is another choice. There are kits available, or you can set up your own system. Not only does drip use less water, an automated system connecting your pots can save you considerable maintenance time. If you’re planning a patio, consider running a drip system under it before you pave, and plan to have emitters emerge from the paving at intervals where you want to add pots.
Periodically submerge hanging baskets and smaller pots to soak the soil completely. This will also help clean out accumulated salts from the outsides of terracotta pots and keep the plants from drying out. In the morning, fill a tub or bucket with cool to lukewarm water. Submerge the pot just to the rim and let it sit for 30 minutes.
Fertilizing Container Gardens
Container plants also need regular fertilizing. You can use either inorganic or organic fertilizer. The former provides quick results; the latter take longer to work but also lasts longer. Slow-release fertilizers and dry fertilizers can be mixed into the soil when you’re planting, and more can be added to the soil throughout the growing season. Liquid fertilizers can be added with a hose-end attachment, watering can, or sprayer. Most experts recommend using a liquid fertilizer every two weeks throughout the growing season.
Pruning & Transplanting Container Gardens
Gentle pruning, especially pinching back faded blooms, cutting off wayward branches, and shaping and shearing plants as needed helps keep your container gardens looking good. You can also prune to keep a plant in check and prevent it from outgrowing its container, but that can be an ongoing battle. If a plant is too large for its pot, transplant it to a larger container.
You can tell if a plant is too large when it starts straining at the sides of the container and the roots start to grow out from the drainage holes. To transplant, gently turn the pot and tap on the bottom until the plant is loosened and can be tilted out of the container. If the plant is stuck, try running a knife between the edge of the pot and the soil. You also may need to pull at the soil with your hands, but don’t pull on the stem or leaves of the plant.
Container Gardening Winter Survival
Containers and the plants in them are vulnerable in cold weather. The containers can crack and break, and the plants’ leaves and roots can freeze. If light frosts are predicted in mild-winter areas, simply watering thoroughly well before the expected frost and adding mulch may be enough. For added protection, you can group pots together.
If the weather will be slightly chillier, consider covering both the pot and the plant. A cover made of thick plastic, fabric, or burlap works well. Because the cover shouldn’t touch the plant, create a cage by driving stakes into the pot or the surrounding ground and draping the cover over it. You can also use a tomato cage, a chair, or a small table. Remove the cover the next morning once the temperatures warm up. To further insulate the pot, wrap it in plastic wrap.
In cold-winter climates, the temperature changes between freezing and thawing that occur in pots mean overwintering is more complicated. The best bet is to move plants to shelter, on a roofed porch or under a deck, into a greenhouse or shed, in a well-lit garage or basement, or in an unheated indoor room. If that isn’t possible, try using a version of the Minnesota tip method. Dig a trench a foot deep and tip both the container and the plant into it. Cover with 18 inches to 2 feet of leaves or straw and top with plastic.