August is when my coleus either turns into the star of the porch and patio or starts looking tired, leggy, and washed out. Here in our little Midwestern town, that late-summer stretch can be hot in the afternoon, humid by supper, and suddenly cool at night before we know it. If you want those deep burgundies, lime edges, copper veining, and velvety purple tones to really glow before fall, this is the month to pay attention. A few small jobs done now make a tremendous difference by September.
I grow coleus in porch pots, along my front walk, and tucked into mixed containers where I need dependable color, and over the years I’ve learned August care is all about timing, light, moisture, and shaping. Below are the steps I rely on every season to push lush growth and richer color, including what to trim, what to feed, when to move containers, and how I handle plants that got a little wild by midsummer. If you’ve got picky spots in the yard like I do, or you’re gardening around a busy family schedule, these are practical things you can do this week.
1. Reassess how much sun your coleus is getting right now
Coleus color is strongly tied to light, and August light is not the same as June light. Trees may cast a different pattern by now, and a spot that was gently bright earlier in summer may have turned too shady. Most modern coleus varieties color up best with about 3 to 6 hours of morning sun or bright filtered light all day. Too little light often gives you larger leaves but duller color, especially on red, maroon, and chartreuse varieties.
If your plant is mostly greening out, move the pot gradually over 4 to 7 days into brighter conditions. I like to shift containers by 2 or 3 feet every couple of days rather than making one sudden move into hot afternoon sun. If your coleus is planted in the ground, thin back nearby annuals that are crowding it or rotate other pots out of the way. On the other hand, if leaves are bleaching tan or developing crisp patches, especially between 1 p.m. and 4 p.m., pull it back into dappled shade. My best late-summer color usually comes from east-facing porches and beds that get sun until about noon.
2. Pinch and trim for bushier plants before fall arrives
August is your last really useful shaping window before cooler weather slows growth. If your coleus has become lanky, pinch the growing tips by 1 to 3 inches above a pair of leaves. That simple cut encourages side shoots and gives you a fuller mound instead of a tall, floppy stem with leaves only at the top.
For badly stretched plants, you can cut back as much as one-third of the total height in one session. For example, a 24-inch plant can safely come down to 16 inches if it is otherwise healthy and still has plenty of leaves below the cut. I avoid taking off more than 40% at once in August, especially if a hot spell is coming, because the plant still needs leaf surface to recover quickly. After trimming, water thoroughly and keep the plant out of harsh late-day sun for 2 or 3 days.
If you have mixed containers, trim the coleus so it complements the arrangement instead of swallowing the whole pot. I do this often around the back step where my coleus likes to overtake petunias and sweet potato vine if I let it.
3. Remove flower spikes as soon as they appear
This is one of the quickest ways to keep the plant focused on foliage. When coleus sends up flower spikes, it starts redirecting energy away from leaf production. The flowers themselves are not ugly, but if your goal is intense foliage before fall, they are not helping you.
Snip flower spikes down to just above a leaf node as soon as you see them, even if they are only 1 or 2 inches tall. Check your plants every 4 or 5 days in August because warm weather can make them appear fast. I keep a little pair of scissors in my gardening basket just for this. On very vigorous plants, removing spikes early often triggers a flush of side growth within 7 to 10 days.
4. Water deeply, but stop the cycle of soggy roots
Coleus likes consistent moisture, but not swampy soil. In August, the biggest mistake I see is alternating between bone-dry and soaking wet. That stress dulls leaf color, causes droop, and can make lower leaves yellow and fall off. In containers, water until it runs from the drainage holes, then wait until the top 1 inch of soil feels dry before watering again. In very hot weather, that may mean every day for small pots and every 2 days for larger 14- to 18-inch containers.
In garden beds, aim for about 1 inch of water per week, or up to 1.5 inches during heat above 90 degrees Fahrenheit. Water at the base rather than overhead if you can. Morning watering, between 6 a.m. and 9 a.m., is ideal because the plant starts the day hydrated and foliage dries quickly. If your pots feel heavy and stay wet for more than 48 hours, improve drainage immediately. Empty saucers, clear blocked drain holes, or repot into fresher mix. Saturated roots can mute color just as badly as drought.
5. Feed lightly with the right fertilizer, not a heavy hand
By August, coleus usually does not need a strong fertilizer push. Too much nitrogen at this stage can give you fast, floppy green growth instead of richer jewel tones. I prefer a diluted balanced fertilizer, something like 10-10-10 or 20-20-20 at half strength, applied every 10 to 14 days for container plants if they have been growing hard since spring.
If you use a water-soluble fertilizer, mix it at 50% of the label rate. So if the label says 1 tablespoon per gallon, use 1 1/2 teaspoons instead. For in-ground coleus, one light feeding early in August is usually enough if the plants were amended well earlier in the season. If leaf edges are burning or the plant seems suddenly weak after feeding, flush the soil with plain water to wash out excess salts. I’d always rather underfeed coleus in late summer than overdo it.
6. Refresh tired container soil and top-dress the root zone
By late summer, potting mix can shrink, compact, and lose its ability to hold moisture evenly. If the soil level in your containers has sunk 1 to 2 inches below the rim, add fresh potting mix or a light compost blend around the plant. This helps insulate roots, improves moisture retention, and gives the plant a small nutrient boost without the shock of full repotting.
Use about 1/2 to 1 inch of fresh mix as a top-dressing, keeping it slightly away from the stems so they do not stay damp. In larger pots, I sometimes gently loosen the top inch of soil with my fingers first. If roots are circling visibly at the surface and the plant dries out by noon every day, move up one pot size, usually from a 10-inch pot to a 12-inch or from a 12-inch to a 14-inch. Do this early in the morning or on a cloudy day to reduce stress.
7. Check for pests hiding under those colorful leaves
Coleus is easygoing, but August can bring spider mites, whiteflies, mealybugs, and aphids, especially on stressed container plants. Pests sap energy from the foliage and can make those rich colors look dusty and faded. Once a week, turn over several leaves and inspect the undersides. Look for webbing, sticky residue, tiny white insects that flutter up, or cottony clusters near the stems.
If you catch them early, a strong spray of water from the hose often handles aphids and whiteflies. For persistent pests, use insecticidal soap according to the label, making sure to coat both the tops and undersides of leaves. Spray early in the morning when temperatures are below 85 degrees Fahrenheit to reduce leaf stress. Repeat every 5 to 7 days for 2 or 3 rounds if needed. I never treat in blazing afternoon heat, and I always test one small section first.
8. Clean up damaged leaves so the good color can shine
By August, even healthy coleus usually has a few torn, scorched, or yellowing leaves lower down. Removing them does more than improve appearance. It increases air flow, reduces hiding places for pests, and helps the plant look fresh again right when you want that late-season color show.
Pinch off any fully yellow leaves, any mushy or spotted foliage, and leaves with more than one-third damage. If a stem is bare for 4 to 6 inches at the bottom, trim it back to a lower leafy node and let the plant regrow. This is especially important in porch containers where everyone sees the plant up close. I think of it the same way I tidy the kitchen before company comes over: a little cleanup makes everything else look better.
9. Rotate pots every few days for even growth and color
Container coleus leans toward the strongest light source, and by August that can leave one side lush and the other side sparse. Turn your pots one-quarter turn every 3 to 4 days. It is a tiny chore, but it helps maintain a symmetrical, full plant with color all the way around.
This matters most on porches, decks, and patios where light comes primarily from one direction. If your coleus sits against a wall or railing, pull it out a few inches so air can move behind it and the back side gets some reflected light. I do my rotating when I water in the mornings so I do not forget. For busy households, pairing two chores like that is often the secret to actually getting them done.
10. Protect color during heat waves with smart afternoon shade
Even sun-tolerant coleus can lose intensity when August temperatures sit above 92 degrees Fahrenheit for several days in a row. Deep reds can look flat, lime leaves can scorch, and dark varieties may droop badly by late afternoon. During those stretches, temporary protection helps preserve both leaf quality and color.
Move pots to a spot with shade after 1 p.m., or use a patio umbrella, lattice shade, or even the filtered shadow of taller plants. For in-ground plants, a simple piece of shade cloth clipped to stakes can make a noticeable difference during a 3- or 4-day hot spell. I’ve even shifted a few porch chairs around to give a prized container a break from the worst western sun. It doesn’t have to be fancy. The goal is to lower stress so the foliage stays velvety and saturated instead of crisp and tired.
11. Take cuttings now in case you want the exact color again later
August is an excellent time to root coleus cuttings because the stems are mature but still growing actively. If you have one plant with especially beautiful color, take several 4- to 6-inch cuttings from non-flowering stems. Remove the bottom leaves, leaving 2 or 3 sets at the top, and place the stems in water or moist potting mix.
In water, roots often appear within 7 to 14 days. In potting mix, keep the medium lightly moist and the cuttings in bright, indirect light. This step will not intensify the mother plant’s foliage directly, but it gives you insurance and lets you preserve your favorite jewel-toned combination. I love doing this with the prettiest porch pots before cool nights arrive. It feels a little like saving a recipe the family loved so I can bring it back next season.
12. Plan for cooler nights so your plants finish strong
In many Midwestern areas, August can surprise you with a few nights in the low 50s by the very end of the month or early September. Coleus does not appreciate cold, and even a single chilly night can slow growth and dull the lush look you worked for. Keep an eye on the forecast once nighttime temperatures start dipping below 55 degrees Fahrenheit.
If your coleus is in containers, be ready to pull it closer to the house, onto a covered porch, or indoors overnight when a cool snap is predicted. For in-ground plants, you can’t move them, but you can protect the root zone with a light 1-inch layer of mulch to stabilize soil moisture and temperature. This is especially useful if your weather swings from hot days to cool nights. Late-season stress management is what helps coleus keep that polished, richly colored finish instead of fading out early.
13. Choose color-boosting companions and remove color thieves
If your coleus is in a mixed planter, look at what is helping it and what is hurting it. Big, thirsty companions can compete for water and nutrients, while sprawling annuals can shade the foliage too heavily. I often thin back aggressive sweet potato vine, calibrachoa, or trailing plants that have climbed over the crown of the coleus.
For the prettiest late-summer display, pair coleus with plants that do not overwhelm it. Upright grasses, small begonias, or airy euphorbia can make the leaf colors look even more saturated. If you have picky family members who prefer “not too busy” planters, this is a nice trick: let the coleus be the colorful centerpiece and keep the companion plants simpler. It reads cleaner and shows off those jewel tones better from the sidewalk and the porch steps.