August is when Boston ferns seem to tell the truth on us. If we’ve been a little careless with watering, a little stingy with fertilizer, or a little late moving them out of harsh sun, they show every bit of it in those brown-tipped, thinning fronds. I’ve grown Boston ferns on porches, under old maple shade, and along a breezeway here in the rural Midwest for more years than I care to count, and I can tell you this much: what you do in August makes all the difference in whether those plants coast into fall looking tired or spill over their pots in thick, graceful green waves.
The good news is that Boston ferns are generous plants when you get back on their good side. A few timely corrections this month can spark a flush of fresh growth before cooler weather settles in. Below are the jobs I never skip in August, from watering and feeding to trimming, pest checks, and preparing for that first hint of autumn chill. Even though your headline says 9, I’m going a little further, because this old gardener has learned there’s usually one more thing worth doing before the season turns.
1. Rework your watering routine for August heat
Boston ferns want evenly moist soil, not swampy soil and not bone dry soil. In August, especially when daytime temperatures run between 82 and 95 degrees, a hanging fern can go from properly watered to crispy around the edges in less than 24 hours. I check mine once in the morning, around 7 or 8 a.m., and again in late afternoon if the day is windy.
A good rule is to water when the top 1/2 inch of soil feels just barely dry. Water slowly until it runs freely from the drainage holes, then let the pot drain completely. For a 10-inch hanging basket, that often means 1 to 1 1/2 quarts of water. For a 12-inch basket, it may take closer to 2 quarts. If the root ball has become so dry that water runs straight through, set the pot in a bucket or tub with 2 to 3 inches of water for 20 to 30 minutes, then lift it out and let it drain.
2. Raise humidity any way you reasonably can
Dry August air is hard on Boston ferns, even when the soil moisture is right. Here in the Midwest, we can have a week of sticky humidity followed by three days of dry wind, and ferns notice every bit of that change. They grow fullest when humidity stays above 50 percent, and they really glow in the 60 to 70 percent range.
If your fern is on a porch or patio, group it near other plants to create a slightly more humid pocket of air. You can also set pots on trays filled with pebbles and water, making sure the bottom of the pot sits above the water line, not in it. Misting alone is not enough to solve dry-air problems, but a light mist early in the morning can help freshen fronds on especially dry days. I don’t mist late in the evening, because wet foliage overnight can encourage fungal issues.
3. Move the plant into truly bright, indirect light
One of the biggest mistakes I see in late summer is keeping Boston ferns either too dark or too exposed. Too much direct sun bleaches the fronds and causes browning. Too little light gives you long, sparse, tired-looking growth. In August, the sweet spot is bright, filtered light for most of the day, with maybe an hour or two of gentle morning sun before 9 a.m.
A north-facing porch is often ideal. An east-facing spot can be perfect if the noon and afternoon sun are blocked. If your fern is hanging on a west-facing hook and gets blasted from 2 p.m. to 6 p.m., move it now. I once had a beautiful old fern my sister gave me lose nearly a third of its fullness in one hard, hot spell because I underestimated reflected heat from a pale garage wall. Sometimes it isn’t only the sun overhead; it’s the heat bouncing back at the plant.
4. Give it a light August feeding, not a heavy one
By August, Boston ferns can still put on good growth, but this is not the time for aggressive fertilizing. Too much fertilizer, especially high-nitrogen feed applied to dry soil, can scorch roots and leave brown tips behind. I use a balanced liquid houseplant fertilizer diluted to half strength, something close to 10-10-10 or 12-12-12, about once every 3 to 4 weeks during active growth.
If you fed in late July, one light feeding in mid- to late August is often enough. Always water the plant first if the soil is dry, then apply fertilizer to already-moist soil. For a standard watering can holding 1 gallon, I mix only half the label rate. Slow and steady does more for a fern than trying to push a big burst of growth all at once.
5. Trim out brown, broken, and bare fronds at the base
August is an excellent month for cleanup pruning. Use a clean pair of scissors or small pruners and remove any fully brown fronds right down at the base where the stem emerges from the crown. If a frond is partly damaged but still mostly green, you can trim off just the brown section, following the natural shape of the leaflet so the cut looks less obvious.
Don’t be timid. A plant with 15 to 20 percent tired growth often looks much thinner than it really is. Once that worn-out growth is removed, light and air reach the center of the plant better, and new fronds have room to unfurl. On a mature fern in a 12-inch basket, I may remove 10 to 25 old fronds in one grooming session if it’s been a rough summer. Within 2 to 3 weeks, that tidying usually pays me back with softer, fresher growth.
6. Check whether the pot is rootbound and correct it fast
If your Boston fern dries out every single day no matter what you do, roots may be crowding the pot. Slip the plant from its container and take a look. If you see a dense mat of roots circling the outside with very little loose soil left, the fern is rootbound. That makes watering difficult because water can skim through the pot instead of soaking in.
In August, you can still move a fern up one pot size if needed. Choose a container only 1 to 2 inches wider than the current one, with good drainage holes. For example, go from a 10-inch pot to a 12-inch pot, not straight into a 14-inch tub. Use a moisture-retentive but airy mix: 2 parts quality potting mix, 1 part peat or coco coir, and 1 part perlite works well. If you don’t want to repot this late, score the outer root mat in 3 or 4 places with a clean knife and refresh as much soil as you can around the edges.
7. Flush out built-up salts from fertilizer and hard water
By late summer, many ferns suffer not from neglect alone but from accumulation. If you’ve been fertilizing regularly or watering with hard tap water, mineral salts can build up in the soil. One clue is a pale crust on the soil surface or around the rim of the pot. Another is browning tips even when moisture seems consistent.
To fix it, take the plant to a sink, tub, or shady spot outdoors and run room-temperature water through the pot for 2 to 3 minutes. The goal is to use enough water to thoroughly rinse the root zone. For a 12-inch hanging basket, I often run at least 1 to 2 gallons through. Let the pot drain completely. This simple flush, done once in August, can improve the look of the fronds within a week or two.
8. Hunt for pests deep in the center of the plant
Boston ferns can hide trouble better than most plants. Spider mites, mealybugs, and scale often tuck themselves into the undersides of fronds or down near the crown where casual eyes never look. In hot, dry August weather, spider mites are especially common. If you notice stippling, a faded look, or delicate webbing, inspect immediately.
Turn fronds over and check with good light. I like to use a plain white paper towel under a frond and tap it gently; tiny moving specks can reveal mites. For light infestations, a strong spray of lukewarm water every 3 to 4 days for 2 weeks can help. In tougher cases, insecticidal soap applied according to label directions is usually safe for ferns, but always test a small section first. Avoid spraying in full sun or when temperatures are above about 85 degrees.
9. Rotate the plant so growth stays balanced and full
It sounds almost too simple, but turning a Boston fern matters. If one side faces the brighter part of a porch or window all summer, that side will bulk up while the shaded side gets thin. To keep the shape rounded and lush, rotate the pot a quarter turn every 5 to 7 days.
This is especially important for ferns hanging near walls, porch posts, or window frames that block light from one direction. I mark the rim of the pot with a small piece of tape so I can remember where I started. Little habits like this are the sort of thing my mother did without fanfare, and I’ve learned she was usually right: the prettiest plants are often the ones that got steady, modest attention.
10. Cut back runners if they’re draining the plant’s energy
Boston ferns produce wiry runners, sometimes called stolons, that extend beyond the pot. They have their purpose, but by August, an overabundance of them can make the plant look scraggly and direct energy away from fuller top growth. If your goal is a dense, cascading basket before fall, it’s perfectly fine to trim many of those runners off.
Use clean scissors and cut them near the crown or just beyond the foliage line, depending on the look you want. I don’t remove every single one unless the plant is badly overgrown, but I do thin them. On a large mature fern, taking off 6 to 12 of the longest runners can tidy the silhouette and encourage a more lush appearance where it counts.
11. Protect the fern from late-summer wind and heat pockets
August damage often comes from moving air as much as temperature. A day at 88 degrees with steady wind can dry a hanging basket faster than a still day at 94. If your fern is near the corner of a house, beside a blacktop driveway, or hanging where afternoon breezes whip through, relocate it to a calmer place.
Look for a site with overhead shade and shelter on at least one or two sides. Under a covered porch roof, beside a lattice panel, or beneath a mature tree canopy can all work nicely. I’ve also learned to be careful about hanging baskets under metal awnings that radiate heat. In the evening, if the pot and fronds still feel warm to the touch long after sunset, the location is likely too hot.
12. Start planning for nights below 55 degrees
If you want your Boston fern to stay handsome beyond early fall, August is the month to make a plan. Boston ferns prefer nighttime temperatures above 55 degrees, and once nights begin dipping toward 50, they can sulk or shed. In some parts of the Midwest, that can sneak up quickly in September.
Decide now whether you’ll overwinter it indoors, in a sunroom, or in a protected enclosed porch. Before bringing it inside later, clean up the plant, inspect for pests, and consider giving it a shower to rinse dust and insects from the fronds. If the fern spent summer outdoors in very bright conditions, remember that indoor light will be weaker, so easing that transition gently will help reduce shock.
13. Use a weekly August checklist so small problems don’t become big ones
This may be the most practical thing I can offer. In August, Boston ferns benefit from short, regular check-ins more than from heroic rescue efforts. Once a week, I do the same five-minute round: feel the soil, look for brown fronds, inspect the crown, check for pests, and rotate the pot. If the weather has been severe, I add a second quick check midweek.
Here’s the simple rhythm I follow: Monday, moisture check; Wednesday, humidity and location check; Friday, grooming and pest check; Sunday, rotate and evaluate whether fertilizer or flushing is needed. It sounds old-fashioned, perhaps, but old-fashioned systems keep a person from forgetting things. And with Boston ferns, consistency is what brings that soft, trailing fullness people admire from the porch steps.
14. Know what healthy new growth should look like by late August
After you’ve made these corrections, you should begin to see signs of improvement within 10 to 21 days. New fronds emerge lighter green, tightly curled at first, then lengthen and soften as they unfurl. The center of the plant should begin to look more active, not bare or stalled. Existing fronds won’t magically repair brown tips, but the overall basket should start reading as greener and denser from a few feet away.
If nothing improves after 2 to 3 weeks, go back through the basics: light, moisture consistency, root crowding, and pests. In my experience, one of those four is almost always the culprit. Boston ferns are not difficult so much as they are honest. When they’re unhappy, they say so plainly. But when they’re content, they reward you with that beautiful fountain of green that makes a porch feel lived in and loved.