Growing Shrubs in Containers

Growing Shrubs in Containers

Jan 04, 2020

Gardeners across North America frequently ask us if they can grow shrubs in containers, and we are happy to say that our answer is always an enthusiastic YES! Garden designers have been doing it for centuries, as it's a perfect way to enjoy year-round beauty and structure anywhere you can set a pot. Here are a few simple guidelines to help assure your success.

Choosing Shrubs to Grow in Planters

Technically speaking, any of our shrubs can be grown in a container. However, if you are planning to keep the shrub in its garden planter all year round, many recommend selecting a plant that is a zone or two hardier than your actual zone (i.e., if you live in zone 5, look for plants that are hardy to zone 3 or 4). This is a very conservative guideline, as it is perfectly possible to be successful with a shrub that is hardy only to your zone, though it does depend somewhat on the plant itself, the container you've selected, and other climatic conditions, such as snow cover, rain, and duration of winter. 

Choosing the Best Container

The easiest way to determine the right container to start with is to use the size of the plant that you purchase:

Pot Size  Container Diameter
Quart   8 - 12"
1 Gallon   10 - 14"
2 Gallon   12 - 16"
3 Gallon   14 - 18"
5+ Gallon   20" +

Look for containers that are proportionally high to wide - you want good volume of soil for the roots to fill. Plus, too small of a container will make watering a real chore. The container must have plenty of open drainage holes in the bottom so that the water will flow freely out instead of backing up in the pot.

Important: Clay and ceramic containers may crack or break when exposed to freezing temperatures, which not only destroys the container but may kill the plant as well. If you live in a cold climate, you must select decorative containers made of materials that can stand up to the weather: plastic, resin fiberglass, wood or metal.

Planting Shrubs in Containers

It may be tempting to fill your container with old plastic bottles or packing peanuts or other such materials. However, we strongly recommend against this: it does nothing to help drainage and actually decreases the volume of soil available for the roots to grow into, which means you'll have to transplant sooner or water more frequently. Instead, fill the entire volume of the container with a good fresh potting mix. There's no need to look for any kind of fancy potting soil either. Anything that's suitable for containers will work for shrubs.

Tip: If you want to prevent soil from washing out the drainage holes, place a small scrap of newspaper or coffee filter over the holes. This won't hinder the drainage and is very effective at retaining soil.

Caring For Shrubs in Containers Spring to Fall

Because of the relatively small volume of soil around the roots, shrubs in containers can dry out quickly and will need frequent watering. The hotter and sunnier the weather, the more water the plant will need. Plan to water at least once a week in cool conditions and three or more times a week in warm or hot weather. There are a few simple ways to check if your plant needs water. 

-stick a bamboo stick about 8" into the soil and pull it out. If it comes out dry, water is likely necessary. If it comes out muddy or has moist soil crumbs sticking to it, check it again in a day or two.

-if your pot is not too large or heavy, you can also try lifting it. If it feels very lightweight, water is necessary.

Tip: The high peat content in most potting mixes can cause the soil to pull away from the side of the container, so that when you water, it flows down the sides and out the bottom without actually watering the plant. Direct the water to the soil surface rather than the sides, and when you see water coming out the bottom, don't assume you've watered enough. Check the actual soil to see that you have.

Caring For Shrubs in Containers in Winter

Provided the shrub is hardy (i.e., able to survive winter) in your area, it should stay outdoors all year. Bringing cold tolerant plants indoors for winter is tricky at best: the fresh air, fluctuating temperatures, and changing day length outside all serve as season cues for the plant's life cycle. If you wish, you may move the container with the plant to a sheltered area out of the harshest winds.

Just because a plant has gone dormant for winter does not mean its water needs have disappeared. In warm climates, shrubs in containers should be checked for water at least twice a week. In cold areas, once every 10 days or so should be sufficient. If the soil is dry, it's not necessary to water like in the summer, with water coming out the bottom. Simply wetting the top inch or so of soil is enough to stave off potential winter drought stress.

Transplanting Shrubs in Garden Planters

Provided its needs for space and proper growing conditions are met, your shrub should grow happily in its container for three years or so, maybe even longer. You'll know it's time to transplant out into the landscape or into a larger container when it becomes very difficult to keep watered, wilts frequently,, and/or falls over frequently.

-Information provided by Proven Winners® ColorChoice®