When to Plant Coleus

Coleus in a greenhouse

Whether you grew coleus plants before or not, you likely have some questions about when to plant coleus. This question depends on whether you are growing from seed, from a plug you purchased at a garden center or greenhouse, or are propagating from a cutting you have.

Knowing when to plant annuals outside can be a difficult choice.

We’ll go through everything involved with planting coleus in today’s post. But first, a little about coleus.

About coleus

Coleus plants are beautiful annuals that can add some stunning color to a container, garden, or border.

While many varieties of coleus will eventually bloom, it’s the leaves of these plants that typically are the focal point. With variegated edges, leaves with multiple colors, and impressive growth, the coleus’ foliage can be very stunning.

Types of coleus varieties

There are hundreds of coleus varieties. Most of the difference you’ll see between varieties will be the color of the foliage, but they can also vary in plant size, leaf shape, leaf size, and plant needs.

Most coleus varieties can be grouped into the following categories:

  • Shade coleus (does not grow as well in full sun)
  • Sun coleus (typically performs well in either full sun or full shade)

For the most part, plant care will be the same for all types of coleus varieties within each category, but you’ll want to check the tag for any specific variety when you purchase it.

When to plant coleus from seed

Determining when to plant coleus from seed (also called germinating the seed) comes down to when you plan to plant the coleus plant outside. Once you have a general idea (typically a safe bet for zone 6 is Mother’s Day, but more on that later), you’ll want to plant your coleus seeds 8-12 weeks before that date.

This will give the seed enough time to germinate, sprout and grow into a sturdy young plant ready to be exposed to the outdoors!

When to plant coleus plants outside

Whether you grew your coleus from seed or purchased a young plant from a greenhouse in your area you’ll want to be careful about when you plant outside.

Coleus loves the warmth, and will in fact tolerate the summer heat very well, but that also means that it may not be able to handle temperatures that are too cold. This is especially the case in the early spring when it may not be very mature or even hardened off as a plant.

While the date will vary depending on where you live, keep in mind that a coleus plant may not be able to survive temperatures below 50 degrees overnight.

If you are growing your coleus in a planter or a movable container, it is advisable to bring your plant in overnight in the spring, even if it’s just in your garage. This protection will help the coleus to become hardier and prepare it for the summer ahead.

If you are growing in the landscape, a bucket (or some other type of protection) can be used to cover the plants in hopes of sparing them.

Check your growing zone

If you are looking for a rough range of time to plant your coleus outside, it’s best to use your growing zone as a guide. Coleus grow very well in PA’s growing zones.

You can find your growing zone, as well as the average last frost dates, using this tool.


When faced with the question of when to plant coleus outside, it’s better to be safe than sorry. Since coleus is a warm-loving plant, you’ll want to make sure the plant isn’t going to be exposed to any temperatures below 50 degrees overnight in the early spring.

If you do have them outside when a late cold snap happens, you can take them inside or cover them up to help protect coleus.

Whether you are growing sun or shade coleus, in PA, we recommend waiting until after Mother’s Day to plant your plugs outside.