When you think "container garden" you probably think of annual flowers, maybe some greens, but shrubs are probably not the first things on your mind. You can use shrubs as your "thriller" plant in a container garden, or you can create a true garden of containers with a different shrub in each pot. If you have a lot of specimen plants, a "container garden" or garden of containers is a good way to display your collection.
For more about how to design a shrub container garden, read our blog post about container garden design with shrubs.
Care Tips for Container Gardening with Shrubs
Once you've designed and planted your garden, you need to keep it healthy! Caring for a shrub in a container over the long run is a bit different than keeping shrubs happy in the ground. Here are some tips.
Plant Selection: Size and Hardiness
Happy plants start with proper plant selection. If you know you're going to grow a shrub in a container long-term, select shrubs that have compact growth habits and that stay small. While you can prune back a full-sized shrub yearly, that's not what's best for the shrub or for you. Additionally, shrubs that stay compact on top will stay more compact on bottom (the roots), so you won't have as many problems with the shrub outgrowing the pot.
Another thing to consider is that shrubs in containers are one zone less hardy than shrubs in the ground. So, if a shrub is considered hardy to zone 6 in the ground, it will be hardy to zone 7 in a container. The roots will get colder over the winter in a container.
Watering can be a bit more complicated if you plant a shrub in a container with annual plants, as the annuals will need more water. The best companions for shrubs in containers are perennials. Once the shrub and the perennials have settled in and grown new roots, they'll need similar amounts of water, which shouldn't be too much. Unlike annual container gardens that will need water every day or every other day in the summer, shrub container gardens can scoot by with once a week, or twice if it's really hot.
Shrubs in containers will require fertilizing once a year. Generally after flowering is the ideal time to fertilize. If a shrub doesn't flower (such as evergreens) fertilize when they're pushing new growth in the spring. There's no need to fertilize more than once a year--that will encourage weak growth. But you will need to give the plants their annual shot of food because, being in containers, they don't have access to the nutrition that they'd find in the soil of a landscape bed.
If you start with compact shrubs, you shouldn't need to do much pruning. However, if you want to maintain size after the first year or two, prune after flowering or after the flush of spring growth. If you're growing evergreen shrubs, read the individual care instructions for the plant because some evergreens respond to shearing or pruning better than others.