In most ways, planting and maintaining a container garden is the easiest form of gardening. All you need is potting soil, plants, and slow-release fertilizer. But container gardening is slightly different from other forms of gardening, mostly due to the fact that the plant isn't in the ground where it can stretch out its roots. Understanding five important aspects will ensure you have success with your container gardening.
Drainage Is Critical
Having adequate drainage in a pot may be the single biggest factor determining if plants live or die. In a traditional garden, excess water drains into lower soil layers, but in a container, excess water can be trapped and drown or rot plant roots unless the water can drain through.
Any pots or other containers need holes in the bottom sufficient to let excess water drain away. Not all pots sold in stores will provide adequate drainage, especially if there is only one small hole in the bottom. If you buy one of these pots, you'll need to be careful to avoid waterlogging the soil—especially if the pot is small—or you can add more holes in the pot before using it. On a metal pot, poke holes with a hammer and pointed tools, such as an awl or even a large nail. Or, use a drill to bore a few good-sized holes in the bottom. On a ceramic pot, use a drill with a masonry bit. (Wear safety goggles whenever drilling, of course.)
Generally speaking, the more drainage a pot has, the better. Many more plants are killed by drowning or rot than by under-watering.
The second part of the drainage equation is ensuring that the soil doesn't drain through the pot with the excess water. Provide a permeable screen or filter material in the bottom of the pot to allow water to pass through but retain soil particles. Any number of materials can be used, such as vinyl window screening, pieces of landscape fabric, coffee filters, paper towels, or sheets of newspaper. The often-used method of putting gravel in the bottom of your pots doesn't work very well.
It is also a good idea to elevate your pots so that the water isn't blocked from exiting out of the drainage holes. You can use any number of ways to elevate your plants, but pot feet are the easiest. If you have a heavy pot, wheeled stands can serve double duty—getting a pot off the ground and enabling relocation.
Removing Plants From Nursery Containers
Transplanting plants from their nursery flats into your garden containers is a crucial step, and you'll be off to a bad start if you don't use care. Novice gardeners often remove nursery plants from their containers by tugging upward on the stems, which may well kill the plant before you even begin. Better methods include:
- On plastic six-packs or four-packs, hold the plant close to the soil line with your thumb and finger of one hand, and then use the other hand to squeeze the plant out of the cell by pinching the pot.
- If the plant is in a nursery pot, you might be able to push the plant up from the bottom. If the plant is root-bound, with roots even coming through the bottom of the pot, you may need to tear or cut off the protruding roots. Then score around the inside edge of the pot to loosen them.
- Larger nursery plants can be removed by turning the pot upside down while supporting the base of the plant at the soil line with one hand, then tapping on the bottom of the pot with the other. This force should loosen the root ball and cause it to slide out onto your supporting hand.
If the plant's roots are dense and encircling its soil tightly when you remove the plant from its nursery container, cut or tear the roots aggressively before planting. This will allow them to grow freely outward, rather than in a circular pattern that can strangle the plant.
Fertilize Before Planting
Container plants can be prone to slow starvation because frequent watering causes nutrients to drain out of the potting soil. The easiest way to remedy this is to mix a slow-release fertilizer into the potting soil before planting the container. Many types of slow-release and time-release fertilizers are available, but a standard granular all-purpose organic fertilizer is a good option.
The two main things to know when planting a plant in a container (or anywhere else, for that matter) concern its roots, in the depth of planting and having optimum soil contact with roots:
- Break up dirt clods in the pot to ensure removal of potential air pockets around roots. You want the plant's roots to be thoroughly in contact with soil. In a crowded pot it may be difficult to avoid air pockets between plants, but be forceful about this, because air pockets cause a plant's roots to dry out and thus retard their growth. A thorough watering immediately after planting helps settle the soil. After watering, fill in any holes or depressions with extra potting soil.
- Situate the plant in the container at the same level as it resided in its nursery pot. The plant's stem should be covered to exactly the same level as it was. (Though if you have a small tomato, you should cover more of the stem, as any part of the stem in contact with the soil will sprout roots, making for a stronger plant.)
Water and Feed Correctly
Watering a container garden is more art than science. Although plants vary in their water needs, when planted in containers, plants may dry out much faster than those planted in the ground—especially if they receive a lot of hot sun, are in black pots, or their containers sit on a hard surface, such as concrete or asphalt. Most plants like to be kept in soil that is moist and damp, though not wet. You may find that you need to water every day. To test soil dryness, stick your finger into the soil up to the second knuckle. If your fingertip feels dry, it's time to water.
Water slowly and check that the water is soaking straight down to the plant's roots, rather than draining down the crevice along the edges of the pot. Water deeply, until you see the water begin to drain out of the bottom of the container.
After planting, feed the container plants with a diluted liquid fertilizer every one to two weeks during the growing season. Container gardens need more regular feeding than plants in an in-ground garden because container plants' access to food is limited by the amount of soil in their pots and the washing away of nutrients by the frequent watering.