Every August, my coleus beds start trying to tell me two different stories at once. One is all summer abundance—leaves splashed with lime, burgundy, copper, rose, and deep green, crowding over porch pots and edging the shady side of the house. The other is a warning. The days begin to shorten, the plants stretch a little, flower spikes appear almost overnight, and if I ignore them for even a week or two, the color I’ve been admiring since June starts looking dull, leggy, and tired. Around here in the Midwest, August is when coleus needs a firm, loving hand.
If your coleus is starting to bloom, fade, or get lanky, this is the month to act. I’ve grown coleus in old enamel wash tubs, front-step urns, cemetery pots, and half-shady beds beside hostas for more years than I can count, and I can tell you this plainly: a few small chores right now can keep those leaves bright until frost. Below are the urgent things I do every August, and I’d encourage you not to stop at just eight. These plants reward attention quickly, and a 10-minute tidy-up today can buy you another 6 to 8 weeks of real beauty.
1. Pinch off every flower spike as soon as you see it
This is the big one. Coleus is grown for foliage, not flowers, and once the plant starts putting energy into seed production, leaf color often weakens and growth gets sparse. In August, I inspect my plants every 3 to 4 days. If I see a flower spike forming in the center of a stem—even if it is only 1 to 2 inches tall—I pinch it out with my thumbnail and forefinger.
Take the stem back to just above a pair of leaves. If the flower stalk is already 4 to 6 inches long, use clean scissors or hand pruners and cut lower, removing the whole tip. Don’t just snip off the tiny blossoms and leave the stalk behind. That usually encourages an awkward, bare stick at the top. A proper pinch keeps the plant bushier and redirects energy into fresh leaves.
2. Cut back leggy stems by one-third to one-half
By August, coleus in part shade can get a bit stretchy, especially if they were planted in a hurry in spring or tucked into a spot with more shade than they really wanted. When stems grow 10 to 16 inches long with leaves spaced far apart, I cut them back by one-third or even one-half. It feels drastic the first time, but coleus responds beautifully.
I like to leave each stem with at least 2 or 3 sets of healthy leaves below the cut. For example, if a stem is 15 inches tall, I might take off 5 to 7 inches. Within 7 to 14 days, side shoots usually begin to form, and the plant looks fuller instead of lankier. On porch pots, I often trim the whole container lightly so it keeps a rounded shape rather than developing one tall side and one bald side.
3. Water deeply, not just often
August heat can make gardeners panic-water, and I understand why. A coleus plant can go limp by midafternoon and look as though it has given up on life. But a quick splash on the surface isn’t enough. I’d rather water deeply 2 or 3 times a week than sprinkle a little every day, unless the plant is in a very small pot.
In garden beds, aim for about 1 inch of water per week, and closer to 1 1/2 inches if temperatures are consistently above 85 degrees. In containers, water until it runs from the drainage holes, then let the top 1 inch of soil dry slightly before watering again. A 12-inch patio pot in full morning sun may need water every day in hot spells, while a large shaded urn may need it every 2 days. The goal is steady moisture, not soggy roots. Dry-wet-dry-wet cycles often lead to stress, dull color, and leaf drop.
4. Feed lightly with a balanced fertilizer
By late summer, many coleus plants have used up the nutrients in their potting mix or planting hole, especially if rain has been heavy. I don’t like to push soft, weak growth this late in the season, but I do like to give plants enough nourishment to maintain rich leaf color. In August, a light feeding works better than a heavy one.
Use a balanced water-soluble fertilizer at half strength—something like 10-10-10 or 20-20-20 diluted according to label directions, then cut in half. Apply it once, and if the plants still look pale 2 weeks later, feed one more time. For container plants, I often use about 1 quart of diluted fertilizer for a 10- to 12-inch pot, and 2 to 3 quarts for large tubs. Avoid overfeeding high nitrogen late in summer, because that can make stems too soft and encourage fast, floppy growth instead of dense, colorful foliage.
5. Move sun-stressed plants before color washes out
Not all coleus varieties tolerate the same light. Some of the newer kinds take more sun, but many still scorch in strong afternoon exposure, especially during an August stretch of 90-degree days. If your leaves are bleaching, crisping at the edges, or losing their deep reds and purples, the problem may not be fertilizer at all. It may be too much hard sun.
I’ve had good luck moving potted coleus where they get 3 to 5 hours of morning sun and then bright shade after noon. In beds, if a plant cannot be moved, I sometimes use a temporary patio chair, taller potted plant, or even a market umbrella to give it a little afternoon protection during heat waves. It sounds homespun because it is, but it works. Once the harsh light is reduced, color often deepens again within 1 to 2 weeks.
6. Thin crowded plants to improve airflow
Coleus likes humidity, but it does not like being packed so tightly that the leaves stay wet and airless. In August, when nights can be muggy and mornings heavy with dew, crowded containers and overfull beds can invite mildew, rot, or general decline. If plants are touching shoulder to shoulder with no room between stems, thin them.
In a mixed container, I remove the weakest stems first or trim neighboring plants that are smothering the coleus. In beds, I like at least 8 to 12 inches of space between average coleus plants, and 12 to 18 inches for larger varieties. It may feel wrong to reduce that lush look, but a little breathing room helps leaves dry faster and keeps the color clearer and cleaner.
7. Remove damaged, faded, or all-green leaves
One thing I’ve learned over the years is that tired leaves tire the whole planting. In August, I go through each plant and pluck off anything yellowed, scorched, torn by wind, or reverted to plain green if the variety is meant to be multicolored. Those green shoots can be more vigorous than the fancy foliage and may eventually outgrow the rest.
Don’t tear leaves roughly from the stem. Pinch cleanly where the leaf joins the stem, or use small snips. If a whole branch has reverted to green, trace it back and remove that stem at its base. This little cleanup sharpens the look of the plant right away and helps you notice pest or watering issues before they become bigger trouble.
8. Check under leaves for mites, whiteflies, and mealybugs
When coleus loses color, people often blame heat or age, and plenty of times they’re right. But pests can drain a plant quietly. At least once a week in August, turn leaves over and inspect the undersides. Spider mites can leave faint stippling or a dusty, tired look. Whiteflies flutter up in a little cloud when disturbed. Mealybugs look like bits of white cotton tucked where leaves meet stems.
If I catch trouble early, I wash the plant with a steady stream of water, especially under the leaves, and repeat every few days. For heavier infestations, insecticidal soap works well if you coat both leaf surfaces thoroughly. Apply in the early morning or evening, not in the heat of the day, and test a small section first. Most problems are manageable if you act within the first week instead of letting them build through the month.
9. Refresh container soil if pots have become hard and tired
By late summer, potting mix can compact, shrink from the sides of the pot, or form a crust that sheds water instead of absorbing it. If water rushes straight down the edge and out the bottom in less than 10 seconds, your coleus may not be getting evenly hydrated. I use a hand fork or even an old table fork to gently loosen the top 1 to 2 inches of soil without disturbing the roots too much.
Then I add about 1 inch of fresh potting mix or compost-rich container blend on top. In larger pots, I may work a little of that new mix gently into the surface. This refresh helps hold moisture better and gives the roots a kinder environment for the final stretch of the season. It’s a simple fix, but on an old porch pot, it can make a visible difference within days.
10. Take cuttings now for backup plants
August is a fine time to make insurance copies of your favorite coleus. I do this every year, especially with a variety whose color I truly love, because one storm, one missed watering, or one early frost can end the show fast. Cut a healthy, non-flowering stem 4 to 6 inches long just below a leaf node. Remove the lower leaves, leaving 2 or 3 leaves at the top.
You can root the cutting in a glass of water or in a small pot of moist potting mix. In water, roots often appear in 5 to 10 days. In soil, keep the cutting lightly moist and out of direct afternoon sun. Once roots are 1 to 2 inches long, pot them up. I’ve kept many cherished coleus going from year to year this way, tucked into a sunny kitchen window over the sink where I can admire them while washing supper dishes.
11. Rotate potted coleus for even growth and color
Container coleus almost always leans toward the best light. By August, one side may be lush and saturated while the other looks sparse. Every 3 to 4 days, rotate patio pots about a quarter turn. It sounds like a fussy little task, but it keeps stems from reaching too strongly in one direction and helps the plant color up more evenly.
This matters especially in urns by porches, garage doors, and railings where light comes mainly from one side. If a pot has already become lopsided, combine rotation with a light trim on the longer side. In a week or two, the shape usually begins to balance out again.
12. Mulch garden plants to hold moisture and steady the roots
Coleus roots sit fairly near the soil surface, and August sun can bake that top layer hard by midafternoon. In beds, I like to spread 1 to 2 inches of shredded leaf mulch, fine bark, or compost around the plants, keeping it about 1 inch away from the stems. That little blanket helps conserve moisture, cool the root zone, and reduce the stress that can push a plant toward bloom and decline.
Out here, we’ve always used what we had—shredded leaves, grass clippings dried for a day, or crumbly old compost from the pile. Nothing fancy is required. The key is not to smother the crown. Mulch should protect the soil, not press damp material up against the stems.
13. Don’t wait too long on end-of-season rescue work
This may be the most urgent advice of all: do these jobs now, not after Labor Day. Once coleus has fully committed to flowering and seed set, and once stems have gone woody and bare, it’s much harder to get that lush midsummer look back. Early August action gives the plant time to push fresh foliage while the nights are still warm and the days are still long enough to support new growth.
I’ve seen many gardeners write off coleus in late summer, assuming its best days are gone. But often the plant is simply asking for a haircut, a drink, a feeding, and a little common sense. That’s one thing country gardening teaches you over and over: timing matters. A bucket fixed before the storm saves a lot of floor-mopping later, and a coleus pinched in August will often stay handsome right up to the first frost in October.
14. Know when fading color is normal and when it is a warning
Not every shift in color means something is wrong. Some coleus varieties naturally deepen in cooler nights, while others soften a bit in intense heat. But if the plant loses contrast quickly, develops smaller new leaves, flowers heavily, and looks stretched all at once, that combination usually means stress or neglected maintenance rather than simple seasonal change.
I tell folks to look at the newest growth first. If the newest leaves are still vivid and well-shaped, your plant is probably recovering or adjusting. If the newest leaves are pale, tiny, or misshapen, step back through the checklist: flowers, water, light, feeding, spacing, pests. Coleus is mercifully quick to answer good care. Give it the right help in August, and it often thanks you before the month is out.