When I was a young gardener, I lived in an area by which I have very little land and no garden shed. While I wanted to have a beautiful landscape, I did not have the space for all the equipment that goes along with it. What to do, what to do? Well, there is a solution and this solution comes from creating seasonal planters that can remain outside. No this is not a dream and yes there are a few conditions by which you need to follow to make this technique work but it is well worth the effort.
To really get this technique to work, you first need to start with the container. As you know, terra cotta pots will crack during cold weather. This is due to moisture getting into the pores of the clay, expanding and causing cracks. These cracks just get bigger over time and expose the roots of the plants to the cold weather. A better choice of container material is needed if your plants are going to survive. This means you need to look at heavy plastic, stone, fiberglass, lead, and iron.
Also, regardless of what the container is made of it needs to have a drainage hole.
The next item on the year round container check list is soil. A good, well-draining potting soil is all that is required.
If you are a forgetful gardener, you may consider adding a slow release fertilizer to your potting medium but do not. Fertilizer encourages new growth and if you have any unusual weather you have no control over the feeding. A better approach is to use a water soluble fertilizer that you apply every time you water. This way you have control over the feeding and can stop in the fall or earlier according to your local weather.
Water in the winter, and yes I said water in the winter. Why? In nature, the roots receive moisture even when the plant is dominant. This is very important to imitate for your plants’ survival. But, unlike nature, do not water once the soil is frozen and the roots can no longer take up the moisture.
Pick your plants wisely. What this means is to pick plants that are two USDA Plant Hardiness Zones colder than you area. How does this work? Well, let’s say your USDA Plant Hardiness Zone is 6. What you want is a plant that has a USDA Plant Hardiness Zone range of 4 through 6 or just 4. In this way, you are covered for that odd cold snap that hits your area.
Finally, while these plants will remain in the pots, this is not a forever thing. They will need to be transplanted every two to three years.
Plants for Extended Stay Container Gardens
While there are numerous plants that can be used in this type of container garden, keep in mind that a lot of times it is simply trial and error. Below are just a few that work well in this type of container garden.
Boxwood (Buxus spp.)
When one thinks of boxwood, they either think of a hedge, topiary or container garden. The reason this comes to mind is the easy by which this plant takes to pruning. The USDA Plant Hardiness Zones for this evergreen are 4 through 9. While different varieties of boxwoods can naturally grow in different shapes, the Green Mountain is one that grows in a pyramid shape without pruning. Also, it is a slow grower and once contained in a pot will only reach a mature height of around 2 ½ to 3 feet.
This evergreen loves to be in partial shade but one downfall of this shrub is the fact that it needs to be protected from strong winds. This can be accomplished by placing near a wall or fence where the winds can be reduced. To keep the pyramid shape looking its best, turn the container often so that the Green Mountain boxwood grows straight and full.
To enhance this planting consider adding a trailing type of plant with interesting foliage and flowers such as ivy geranium or variegated ivy.
Arborvitae (Thuja spp.)
The arborvitae is an upright shrub that many a container gardens have contained. The reason is the broad USDA Plant Hardiness Zones of 2 through 9 and the fact that it stays a beautiful green color year round with little effort. This shrub thrives in full sun but it can tolerate a little bit of shade. While the mature height of this plant can reach 15 feet, planting it in a container will keep it less than four feet.
The only disadvantage to this plant is the fact that it is green, which is a common color during the growing season. To really show off this plant, allow the height to be the showpiece of the container garden arrangement. Add a splash of unexpected color at the base of the arborvitae, which can come in the form of annuals such as marigolds or begonias along with a trailing plant such as variegated ivy.
Juniper (Juniperus spp.)
While any spreading type of juniper will do, the Blue Star is good choice. First, the USDA Plant Hardiness Zones are 4 through 9. The second advantage of this shrub is the fact that the mature height of this plant is three feet and the spread is three to four inches. Yes, the range and mature size of the shrub is very important but what makes it a standout beyond the fact that it is a slow grower is the color. The common name for this spreading shrub is Blue Star and rightfully so. The needles on this evergreen are a steel blue color, which adds a color contrast to most container plantings. Also the fine texture of the needles adds just more designer element.
The juniper loves to be in full sun but it can tolerate partial shade.
Redtwig Dogwood (Cornus alba)
As the name implies, the twigs on this dogwood are red but do not get confused with the dogwood tree. The redtwig dogwood is a shrub and if you can find the variegated variety you have double the visual impact. First, the leaves are grayish green with white margins. While the leaves somewhat hide the red stems of this shrub, once fall comes and leaves drop off the red color of the branches shines through. Having said that though only the young twigs actually have the showy red color the older branches on the other hand will end up being a muted red. To enhance that red color, cut back the older branches so that the young twigs can really show off and give you the biggest impact possible.
Beyond the visual interest this plant can give an extended stay container garden is the fact that the USDA Plant Hardiness Zones for this shrub is 2 through 8, which covers a large area that can use this plant.