7 Late Summer Tasks For a Healthy Fall Garden
Late summer sets the stage for how your garden performs through fall and into next year. These essential tasks might not seem urgent now, but skipping them means dealing with bigger problems later. Gardening expert Madison Moulton explains what to tackle while there's still time.
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In late summer, spring planting is finished, summer maintenance is winding down, and fall might seem a little too far away to worry about. But late summer is when you prevent problems instead of fighting them later on.
Most garden disasters that hit in fall actually start developing in late summer. Disease spores build up on stressed plants. Pest populations reach their peak. The list goes on. Take care of these issues now, and you’ll have little trouble through fall.
Follow this list of late summer gardening tasks to set yourself up for success. A little effort now prevents the kind of problems that can ruin entire seasons if left unchecked.
Divide Overcrowded Perennials
Perennials that have been in place for several years often start looking tired and producing fewer flowers. The centers die out, leaving hollow rings of growth that look untidy and perform poorly. Late summer division fixes these problems and gives you extra plants.
Spring-blooming perennials like hostas, daylilies, and iris divide best in late summer when they’re done flowering but still have time to establish before winter. Fall-blooming plants should wait until spring division instead.
Look for plants with dead centers, reduced flowering, or clumps that have grown much larger than their allotted space. These are prime candidates for division, even if they don’t look terrible yet.
Dig up entire clumps and pull or cut them apart into smaller sections, making sure each division has good roots and several growing points. Replant divisions immediately and water them well until they settle in.
Cut Back Diseased Plants
Plants showing signs of disease need attention before spores spread and overwinter in your garden. Powdery mildew, black spot (particularly on roses), and other fungal problems often peak in late summer when humidity is high and plants are stressed.
When completing this late summer gardening task, remove affected foliage completely. Diseased leaves left on plants or dropped on the ground provide overwintering sites for next year’s problems. Phlox, bee balm, and roses are common targets for late-season disease problems. Cut these back, removing the most affected growth and improving air circulation around remaining stems.
Clean up fallen leaves and debris from around diseased plants. It’s a disease magnet that will cause problems when conditions warm up next year.
Don’t compost diseased plant material unless your compost gets hot enough to kill pathogens. When in doubt, bag it up for disposal instead of risking disease spread.
Start Fall Weeding
Weeds that go to seed now create massive problems next spring. One plant can produce thousands of seeds. Stop them this month as part of your late summer gardening tasks before they set seed, and you’ll prevent thousands of future weeding sessions.
Focus on perennial weeds first since these are harder to control once established. Dig out deep-rooted weeds while the soil is still soft. Annual weeds are easier to pull but more urgent since they’re racing to set seed before frost. Get them while they’re flowering but before seed heads mature and scatter everywhere.
Manage weeds as they sprout through fall. Cooler weather often triggers another germination flush. A few minutes spent weeding weekly prevents hours of work later.
Plant Fall Color
This is definitely one of the more exciting late summer gardening tasks. Fall gardens require planning and planting that starts in late summer. Many fall-blooming plants need to be in the ground now to establish before their flowering season.
Asters and other fall bloomers often go on sale in late summer at garden centers. Plant them now rather than waiting for fall, since established plants perform better than newly planted ones. Fall vegetable gardens also need attention in late summer. Cool-weather crops like lettuce, spinach, and radishes can be planted now for fall harvests.
Consider ornamental cabbages and kales for fall container displays. They don’t look like much in summer heat but become gorgeous as temperatures cool, providing color that lasts through several frosts.
Don’t forget about spring bulbs if you want early color next year. Many bulbs need to be ordered in late summer for fall planting, and popular varieties sell out early.
Water-Stressed Plants
Plants that struggled through summer heat need deep watering to recover before fall weather arrives. Shallow-rooted plants and newly planted species are particularly vulnerable to heat stress damage.
Water deeply to encourage deep root growth. Frequent shallow watering creates weak root systems that can’t handle drought or cold stress effectively. Focus extra attention on plants that showed stress signs during summer. These plants need help recovering before winter preparation begins.
Mulch around stressed plants to conserve moisture and moderate soil temperature swings. This helps plants recover more quickly while reducing ongoing water needs. It also improves soil structure over time.
While you’re at this late summer gardening task, check irrigation systems for problems that might have developed during the summer season. If plants start looking stressed for no obvious reason, it could be clogged emitters.
Assess Pest Problems
Late summer pest populations can reach their seasonal peak just as gardeners start paying less attention to their plants. These pests can cause significant damage if left unchecked through fall.
Treat pest problems now while temperatures are still warm enough for treatments to work effectively. Choose ones that are safe for beneficial insects to avoid impacting local pollinators. Selective treatments that target specific pests work better than broad-spectrum products that kill everything.
Prepare Tender Plants for Transition
Plants that can’t handle frost need preparation during your late summer gardening tasks, before nighttime temperatures start dropping unexpectedly. Tender species require different strategies depending on your climate and growing situation.
Container plants have the advantage of mobility. Move them to protected locations or bring them indoors when needed. Start acclimating indoor plants gradually rather than waiting for the first frost warning. Garden-planted tender perennials might need protection in place with frost covers.
Reduce fertilization for tender plants to slow growth and help them prepare for dormancy or indoor conditions. Soft, actively growing plants handle cold stress poorly.
