The Elements of Successful Container Gardening

A stoop with container gardens
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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. Here are five lessons to ensure success with your container gardening

Drainage is Critical

Having adequate drainage in the pot may be the single biggest factor determining if plants live or die. In a traditional garden, excess water generally drains down into lower soil layers, but in a container, excess water can be trapped and drown plant roots unless there is a way for the water to drain through.

Make sure that your pot or container has holes in the bottom that are sufficient to let excess water drain away. The standard pots sold in stores may not provide adequate drainage, especially if there is only one tiny hole in the bottom. If you buy one of these pots, you'll need to be very careful watering to avoid water-logging the soil or add more holes in the pot before planting. On a metal pot, you can 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.)

Generally speaking, the more drainage a pot has, the better. Many more plants are killed by drowning than by under-watering. 

The second part of the drainage equation is making sure that the soil doesn't drain through the pot while the excess water drains out. You need to provide some permeable screen or filter material in the bottom of the pot that will allow water to pass through but keep soil particles inside. 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. There is any number of ways to elevate your plants, but pot feet are the easiest.

planting a container garden
 Illustration: © The Spruce, 2018

Be Careful When Removing Plants From Nursery Containers

Moving plants from their nursery containers into your garden containers is a critical 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. Here are better methods:

  • On plastic six-packs or four-packs, hold the plant close to the soil line with the thumb and finger, on the one hand, then use the other hand to squeeze the plant out of the cell by pinching it. 
  • If the plant is in a nursery pot, try pushing it out by pushing up from the bottom. If the plant is root bound, you may need to tear or cut off the roots protruding through the bottom holes, then score around the inside edge of the pot to loosen the roots. 
  • 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 hand. This force should loosen the root ball and cause it to slide out onto your supporting hand. 

If the plant's roots are very dense and root bound when you remove it from its nursery container, cut or tear the roots aggressively before planting. This will allow the roots to grow freely, rather than in a circular pattern that can strangle the plant.

Fertilizer Adequately

All plants need nutrients to survive and thrive, and 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. There are many types of slow-release and time-release fertilizers available, but a standard granular all-purpose organic fertilizer is a good option. 

After planting, also feed the container plants with a diluted liquid fertilizer every 1 to 2 weeks during the growing season. Container plants have limited access to nutrients because of the limited amount of soil in containers and the frequent watering, so they need more regular feeding than plants in a traditional garden environment. 

Plant Carefully

There are two main things to know when planting a plant in a container (or anywhere else for that matter):

  • Make sure the plant sits in the container at the same level as in its nursery pot. The plant's stem should be covered to exactly the same level as it was in the nursery pot. 
  • Make sure there are no air pockets and that the plant's roots are surrounded by soil. In a crowded pot it may be difficult to avoid air pockets between plants, but be forceful about this, because air pockets will cause the plant's roots to dry out. A thorough watering immediately after planting will also help settle the soil. After watering, fill in any holes or depressions with extra potting soil

Water Correctly

Watering a container garden is more art than science. Although plants vary in their water needs, when planted in containers, most plants like to be kept in soil that is moist and damp, though not wet. To test soil, stick your finger into the soil up to the second knuckle. If your fingertip feels dry, it's time to water.

Water slowly and make sure 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 the bottom of the container.