Six weeks ago that bed by the driveway was full of colour and life. Now the coneflowers have gone brown and papery, the catmint has flopped sideways onto the lawn, and things just aren’t looking as vibrant as they once did. That’s the August garden slump, and every perennial garden across Kingston hits this same wall around the same time each year. Early bloomers are finished, the July heat has stressed everything else, and the whole bed just looks worn out. Reviving a tired perennial bed this late in the season is possible but comes down to doing the right things in the right order.
Why Perennials Hit a Slump in August
Look closely at a spent coneflower head in August and it isn’t actually dying rather it’s just done for the year. Perennials that bloom in spring and early summer, like peonies, iris, and baptisia, put on their show back in June, so by August they’re tired foliage, with nothing left to give. Add a run of hot, sticky weeks on top of that and even the healthy plants start dropping lower leaves or flopping under their own weight. None of this means anything is dying rather it usually just means the plant is done with this round of growth and ready for a nudge toward its next one.
Cutting Back Perennials in Late Summer for a Second Flush
Take a pair of shears to a catmint that’s flopped over in early August, cut it back by a third to half its height, and for the next two weeks it’ll look worse before it looks better. Bare stems, no flowers, nothing to show a neighbour walking by. Then fresh foliage fills in, and on a good year you’ll get a smaller second flush of blooms before the first frost shows up. Some gardeners call this the Hampton Hack. Coneflower and hardy geranium take the same treatment just as well as catmint does.
Not every perennial wants this, though as phlox and daylilies would rather just have their spent blooms removed. Cut those back hard this late and they’ll often look worse heading into fall, not better, so it’s worth knowing which plants in your bed actually want the harsh treatment before you start swinging shears at everything.
Deadheading Perennials for Rebloom
Deadheading is the gentler of the two, and the one most beds need more often. Snip a spent flower and its stem back to the next bud or leaf node and you’ll often coax rudbeckia or shasta daisies into another round of blooms without touching the rest of the plant. Save the harder cutback, the one that takes the whole plant down, foliage included, for perennials that have gone properly ratty, not just a little tired.
Dividing Overgrown Perennials: Signs Your Bed Needs It
When you pull an iris or daylily clump apart in August you’ll be able to pinpoint the issue pretty fast. A dead woody centre that’s ringed by a crowd of vigorous new growth trying to push outwards but without the room. That’s when perennials should be divided since no amount of fertilizer can fix crowding the same way that a spade does. Cooler nights in September help newly divided plants get their roots down with plenty of time before the ground freezes. The only exception would be peonies which should be left until they’ve gone fully dormant. Dividing up a big clump correctly can give you three or four plants instead of one giving you plenty of greenery to fill in the gap that’s been left.
Garden Bed Mulch and Soil Care in August
When you inspect most of your beds around mid August, that mulch you’d previously laid down has thinned and dried out to almost nothing. Bare soil is visible between the plants and weeds are starting to appear thourgh the cracks, Pull those weeds out now making sure you get the roots before they go to seed and are an issue again next year. Top the bed back up with 2 – 3 inches of fresh mulch to help hold moisture underneath while providing protection from weeds and temperature fluctuations.
Best Late Summer Blooming Perennials for Ontario Gardens
Cutting back and dividing solves the tired part of a bed. It doesn’t fill the gaps left behind. Sedum, rudbeckia, asters, and Russian sage are just hitting their stride right as everything else winds down, and they’ll carry a bed into September and October without much fuss. Mums are the exception worth a second look at the tag. Most sold at garden centres are grown for one big autumn display, not for coming back next spring, so make sure to check before you plant one.
When to Bring in Help
An afternoon with pruners and a little bit of work can completley revitalize your perennial beds. Older beds that haven’t been divided in a few years tend to be a bigger job than most would like to handle solo. Our garden centre carries the late summer perennials mentioned here and our crews can handle garden maintenance across Kingston and surrounding areas. Whether its a single overgown bed our you’re in need of a full renovation, we have everything to make your project a success.
