Container gardens are perfect for small urban gardesn. Maintaining container-grown plants means keeping them well watered, fertilized, and pruned; and keeping pests at bay. Containers in the city can heat up fast and furious in full sun. These simple maintenance tasks keep your patio planters and window boxes looking their best throughout the growing season and help cold-climate gardeners prepare for winter.
- Watering. Under- or over-watering is the number one reason why plants in containers fail. If you don’t have the facilities and time to keep your containers watered then you should reconsider whether you actually want to have them or not. When you water, be sure to saturate all the soil in the pot-not just around the edges. Pots that dry out too quickly may have more plants in them than the soil can support. Remove some plants, prune them back, or move the pot to a less sunny location. But don’t lose heart! If you have the time or money to spend, there are plenty of ways in which you can make watering a bit easier.
- Fertilize regularly. Rapidly growing plants need plenty of nutrients. Frequent watering and the limited amount of soil in container gardens makes the need for fertilizer critical. Mix slow-release fertilizer pellets into the potting soil, according to package instructions. Add additional nutrients throughout the growing season by dissolving a water-soluble fertilizer in the watering can once every week or two. Use a one-half to one-quarter strength dilution, or follow package instructions. You can also use organic fertilizer products such as compost, fish emulsion, and cottonseed meal in your containers. The key to adding these fertilizers is to stick with it.
- Feeding. Assuming you added a slow release fertiliser to your compost when planting up your container, this should provide enough food for the lifespan of temporary displays. However, if you have permanent plants in your containers then you will need to top up their food supply periodically. Unless your plants are showing indications of a nutrient deficiency, you should aim to give them a balanced feed, containing nitrogen, potassium and phosphorous. You may wish to give them a fertiliser with a higher proportion of potassium in their flowering season to encourage the production of more flowers (specialist tomato feeds are a good choice for this purpose).
- Groom and remove dead flowers. Keep plants looking lush and full by pruning leggy stems back to buds or branches and removing off-colored and damaged foliage. Many plants continue to produce new flowers if you remove the spent blooms before they set seeds. Pinch the flower stems back to just above a leaf or bud.
- Prepare for winter. In cold-winter climates, containers and their contents need protection from freezing temperatures. Even hardy perennials, trees, and shrubs cannot tolerate completely frozen roots. Terra cotta and ceramic pots may crack if left outside to freeze. Empty their contents into the compost pile and store the dry pots in a protected garage or cellar. Wrap chicken wire around the pots of small trees and shrubs and stuff with loose mulch, such as straw. Store in an unheated but not freezing garage or basement for the winter.