Plants in containers are easy to maintain and control. Feeding and
watering can be regulated and monitored, while deadheading and pruning
are simple, as plants in garden pots are movable.
When a plant’s season of interest has
passed, you can simply replace it. Plants that grow too vigorously in
open ground, such as some bamboos, are restrained by pots, while
slower-growing species that are easily swamped in a border can be
pampered. Pests and diseases are easy to treat, and plants can be lifted
above soil level away from slugs and snails. However, plants in pots
depend on you totally for their food, water, and general care, whereas
the same plants in open ground will survive with far less attention.
Containers dry out quickly, especially in hot or windy weather. Some plants, like camellias and rhododendrons, do not set flower buds properly if they are short of moisture. Being evergreen, they need watering all year. Pots close to walls and fences or under trees do not receive much rainfall, so keep an eye on them. The signs of lack of water are obvious—wilting, yellowing foliage, and in extreme cases falling leaves. Use a watering can, or a hose with a wand or nozzle, so you can moderate the flow of water. The plant has had a thorough soaking once water flows from the bottom of the pot. Surface compaction may prevent water from soaking in at all; push a hand fork into the soil a few times to remedy this. An irrigation system is the most reliable way to keep plants watered. Small-gauge pipes with adjustable nozzles are placed in the pots; water can be controlled by a timer. A piece of slate or crock can be used if you don’t have a watering wand. Place it on the soil as you water, and it will help distribute the flow evenly.
Plants in containers need fertilizing from late spring to mid-fall for healthy growth and a succession of flowers. Fertilizing is usually done every two weeks, though hungry plants, such as tomatoes and brugmansias, need it weekly. The simplest method is to add water-soluble fertilizer to the watering can. Controlled-release fertilizers avoid the need for continual feeding, as the fertilizer is released over several months. These are available as pellets, sticks, or small p lugs, which are pressed into the soil once the plant is in the pot. Alternatively, buy granules and mix them into the soil before planting. All forms are useful in a low-maintenance garden. Controlled-release fertilizers are also the best option for containers packed full of plants, such as hanging baskets. Follow the manufacturer’s guidelines; over fertilizing can be fatal. Adding well-rotted manure to the bottom of the pot when planting, or sprinkling pelleted chicken manure on pots in spring, are good organic alternatives. Water-retaining gel is useful for those who occasionally forget to water; it is excellent for hanging baskets, which dry out quickly. The gel stores moisture around the root ball, creating a reservoir for the plant to draw on in dry periods. Add the gel granules to the potting mix at planting time, following the directions on the packet.
Repot regularly in spring, using a new pot only slightly larger than the original. Potbound plants are often top-heavy, and hard to water, with little space for water to collect on and seep into the soil without spilling over the edge or running down the inside of the pot. Foliage may be yellow, and new growth reduced. If you want to keep an overgrown plant in the same pot, either prune it, or divide it and replant in fresh potting mix. Also, top-dress potted trees and shrubs in spring by removing one-third of the soil, without damaging the roots, and replacing it with fresh. Moving heavy pots, even when empty, is not easy. Grow plants that will be moved regularly in light pots and soilless potting mix. Plant movers—metal or wooden stands on wheels, and equipped with brakes—are useful for heavy containers.