How to Grow a Coleus StandardPlants & Flowers Last Updated On 01/21/2022
Some of the common plants used in topiary, such as bay and rosemary, look very beautiful and will make your garden stunning. However, one big downside to these plants is that they take years to mature.
If you wish to have your topiary in a short time, such as six months to one year, you may try something different. Growing a coleus can do the trick: these plants grow fast and look very beautiful and rich in any garden.
Most varieties of coleus are suitable. Coleus plants are known for their foliage colors and patterns, so there are many variations to choose from. There are also difference in sizes: some will grow up to 2-3 feet while there are others that may grow to 4-5 feet or taller.
Potting Up Your Coleus
Once you have your chosen coleus, it's time to pot it up. The size of your coleus is not important, but make sure that your plant has a straight center stem (known as "the central leader"). If you have a small plant, a simple 4-inch pot is enough - you will move it to a larger pot as it grows. Make sure to always give your plant enough space to grow roots: this will make it taller. Once it's grown to about 3 feet, make sure to repot your coleus to a heavier, 12-inch container (terra cotta containers are great for this). Smaller varieties should be repotted when they are about 2 feet tall and moved to a 8-inch container. Use a regular potting mix, water your plant regularly and fertilize it once per month with a 15-30-15 formula.
When the plant is about 8 to 10 inches tall, it's important to start thinking about staking. Tie it up to a bamboo stake for support and make sure that the stake is a bit taller than the plant itself. It's best to do this during repotting. Attach the stem to the stake using a piece of twine or strech tie in a figure 8. Whenever you move the plant to a larger container, add heavier and taller stakes for support.
Pinching and Pruning Coleus
Your main concern is to keep your coleus straight. Don't worry about the leaves growing along the main stem. They will help feed the plant and will eventually drop off. However, you need to take care of the branches. They will form at the leaf axils (the spot when the leaf meets the main stem). Catch them early and simply pinch them out or rub them off.
When the coleus reaches the height you want, snip off the central leader - this will encourage the branches to form a full, rounded head. If your goal is a tabletop standard, start snipping at about 1 to 2 feet. If your plant will sit on the ground you will probably want something larger (3 to 5 foot). Don't forget: when you snip off the central leader, the branches that form will be a few inches taller than where you've snipped.
To maintain the best anesthetic, you should aim for the ratio of 2/3 stem to 1/3 head. It means that if the plant is 36 inches tall, the bare stem should be 24 inches and the head of the standard about 12 inches. When branches develop at the head, prune them back to the second or third node from the stem. This will encourage more side branches to emerge, which will help your coleus to fill in. Every time a branch is pruned, it will form two more. The branches that form along the nodes you pinched in the past are known as "secondary growth". Make sure to keep them cut back to about 2-3 nodes long. In case the flowers form, it's best to remove them - you wish the plant to put all its energy into the foliage.
- At this point, fertilize your coleus once per week at 1/4 strength with a 10-10-10 formula.
- Don't forget to keep pinching the tips so the plant stays in shape.
- Make sure that your coleus is sheltered and secured on windy days.
- Repot your plant every year and do a bit of root pruning, if needed. Carefully remove the plant from the container and brush off as much soil as you can. Look for roots that are thick and woody and trim them back. Repot the plant in fresh soil in the same container.
- If you keep your coleus indoors, place it in a sunny south or east facing window. Using fluorescent light may also help. Keep the coleus out of drafts so the foliage doesn't drop.
- Water regularly during winter but stop fertilizing until early spring. It's important to give your plant a rest.
- Don't worry about the coleus losing some foliage or color during winter: this is normal. It will go back to its rich beauty in the spring.
Photo credit: Dan Keck