Is Coleus an Annual, Biennial or Perennial Plant?
Want to start planting some coleus this season, but aren't sure if it's an annual, biennial, or perennial plant? The answers to these questions will largely depend on your geographic location. In this article, certified master gardener Laura Elsner breaks down the life cycle of the coleus plant.
Coleus are a foliage lover’s dream. They provide color and texture to garden beds and pots without flowers. Every year I go to the garden center and buy some coleus for my garden pots and to brighten up shady areas in my garden. I treat them like annuals, and purchase them along with my petunias, zinnias, and geraniums. But are coleus actually perennial?
When the season ends, I throw out my coleus along with my other annuals. I also spend my summer season meticulously deadheading the bland purple flowers from my coleus in order to let their foliage shine. But if I left the flowers on and didn’t pull them out in the fall, will they self seed? Will they produce new baby coleus in my garden from the coleus I planted in previous years?
Let’s explore these questions and discuss ways to prolong the life of the beautiful coleus plant.
The Short Answer
Coleus are considered perennial plants, but are usually treated as annuals. For coleus to return each season, you need to be in a tropical climate that has partial shade. These plants are frost sensitive, and treated as annuals in any hardiness zones that are lower than zone 10.
The Long Answer
Coleus are actually perennials! Buuuuut… Only if you live in zones 10+. In the United States this only includes Hawaii, Puerto Rico, and the southern tip of Florida.
So if you live in one of these places your coleus will be perennial. If a coleus doesn’t receive any frosts it can live for several years in a garden. Even when planted in zone 10+, they will need plenty of moisture, and shade to thrive. Only certain coleus varieties perform well in gardens with full sun exposure.
For gardeners in zones 10 and below, coleus is treated an annual. But that doesn’t necessarily mean you have to throw it out every season. There are ways to prolong the life of your coleus, which includes planting them in pots.
Annuals vs. Perennials
A true annual will grow, flower, produce seed, and die all in one season. I will use calendula as an example of this. It grows, makes beautiful orange flowers that turn to seed, it drops the seed and then is finished. The next season you will have calendula if you let it seed itself, but it will be the children of the previous year’s plant, not the original plant. This is the definition of a true annual.
A perennial on the other hand, like a saliva plant, will grow and then flower, which will produce seed. The seed scatters and the plant goes dormant. It will scatter seeds and create new plants, but the original parent salvia still grows and exists. This is a perennial. A coleus technically fits into this category, as long as it doesn’t succumb to frost.
However, as gardeners we tend to lump things together a little differently. We leave the science for the botanists and use terms for how we use them in a garden. So to a gardener, an annual simply means a plant that lasts through the summer season and then is disposed of after the season ends.
I live in zone 3, so I consider a lot of things annuals. I use agapanthus as an annual, when I know it is a very popular perennial in California. Coleus fits into this category. It is technically a tender perennial, but for most gardeners, we consider it an annual.
Do Coleus Self Seed?
Self seeding happens when flowers go to seed and then the seeds make new plants. This happens in flowers like pansies. If you don’t deadhead them, they will go to seed and then you will end up with little pansies, and little violas called Johnny Jump-Ups, scattered through your garden.
This can be really lovely, but can also get out of control really quickly. The self seeded annuals will self seed and on and on until everything is covered in pansies and violas.
Coleus actually self-seed too. But there are a few things you will have to keep in mind. First, you will need to live in gardening zone 7+ in order for the seeds to survive. Second, your coleus will need to flower.
I always pinch the flowers off my coleus right when I see them. Once they start flowering, the leaves (which are the spectacular part) start to get smaller as the plant focuses its energy into blooms.
So if you want your coleus to self seed you will have to let it bloom in order to produce seeds. Third, a lot of the new and funky varieties of coleus are hybrids. This means their seeds won’t come true. They won’t look like the funky variety you purchased as a plant. Instead, they usually look like a more plain or generic coleus.
So yes, if you live in zones 7+ your coleus can self seed. However, I would not consider this the most reliable method to have a continuous supply of coleus in the garden. They aren’t vigorous self seeders, they need to flower in order to seed, and the seedlings don’t always look like their parent plants. If you live in an area where coleus are perennial, perhaps let them self seed and fill in around the parent plant.
I totally get the appeal of planting a plant only once and then it seeds and you have a never ending supply of it in your garden. My front flower bed has been a carpet of self seeding calendula for years. I get so many compliments on the bright orange carpet of flowers, and I do nothing but let them seed. It saves me money, and work, because I’m not planting them as annuals every year.
Overwintering is something a lot of lower zone gardeners, like myself, do in order to save some money. I save agapanthus and alocasia bulbs, coleus, and some ivy. I’ve even gone so far as digging a grave for a tender topiary rose to overwinter.
Some of these things are harder to do than others. I really like overwintering coleus because it is easy, they make an attractive houseplant, and they actually don’t bring in any bugs with them.
I’ve never seen coleus self seed vigorously, as they will be smaller plants that may not be able to produce flowers and seed in time to reseed and produce a new crop of coleus. They also don’t always appear like the beautiful variety you originally planted. So instead of relying on self seeding, overwintering ensures an endless supply of beautiful coleus plants that are literal clones of their mother plant
There are main ways to overwinter a coleus plant to have them for the next season. The first way is to grab cuttings from a coleus and root them into soil and bring them inside for the winter. Just take a six cell pack (or any containers) and fill it with evenly moist potting mix.
Healthy Plant Cuttings
Cut off some new, green shoots from your coleus plant. Woody stems do not root as easily. Dip your green cutting into a rooting hormone (this isn’t necessary, but it does help them root a lot faster) then place a dome lid or baggy over them and keep them out of the direct sun for about a week.
Take off the lid, and voila! New baby coleus. These are clones of the parent plant. I like this method if you live in an area with a very short winter season. You make the cuttings and can have them start growing for the next season’s crop. If you have a greenhouse to store them in, even better.
Overwintering in Containers
But, if you are like me and have a very long winter season, having lots of rooted cuttings to babysit all winter is quite a task. That is why I bring a whole coleus plant inside over the winter. I dig it out of the container or bed and transplant the coleus plant into a nice pot (with drainage). Then I treat my coleus as a houseplant for the majority of the winter.
I water it, and keep it in a sunny window. Then when it is 8-12 weeks before the final frost date in my area I start taking cuttings of my coleus from the mother plant and I do the process that I mentioned above. This way I am only dealing with one coleus for most of the winter, and it is an attractive houseplant.
Either of these methods can be done year after year. You can essentially take cuttings of cuttings of cuttings until the end of time. This requires a bit of effort, but it saves money.
So, scientifically speaking, yes coleus are tender perennials. Which means they can live for several years if they don’t succumb to frost and winter. If you live in zones 10+ your coleus will live perennially. If you live in a zone below 10, your coleus will most likely be treated as an annual. However, you can overwinter it and then replant it, or cuttings of it, in your garden.
Coleus will self seed if you live in zones 7+. However they will not be reliable. They need to be left to bloom in order to seed, and they will not look like their parent plants. So if you’re looking for a uniform and spectacular display of coleus, you will need to either purchase them as annuals every season, or overwinter them and replant them the next season.