August may feel hotter than Hades but believe it or not, now is the time to add pops of color to your garden bed, as well as start your preparations for cooler weather. Gardening is all about delayed gratification, and it’s the ideal time to put in the hard work now so your yard looks full and colorful come spring. 

Weed. Like, Really Well. 

Gloved hands weeding an overgrown gardenNo one wants to be hunched over in the sweltering sun and suffocating humidity to pull some opportunistic weeds, but if you’ve been neglecting this duty all summer, it’s time to brace yourself and get down to it. Late summer is when those little pesky plants start to produce thousands of seeds that will germinate and become more pesky plants in the spring. The key to getting out there is having the right mindset: It’s War. Wage battle against your enemies now, before their ranks swell and overtake your own forces. And be merciless. Be sure to pull out the roots by hand or by hoe, because many common weeds can easily regenerate from any root left in the soil. Then, like any good conqueror, be sure to lay down a thick layer of mulch to squash any further uprisings.

Divide Perennials

Person dividing a hosta plant with a spadeTo continue our metaphor, we could say that in addition to eradicating enemy weed forces August is also a good time to grow your own ranks. Late summer is the perfect time to split perennials that have hopefully flourished all summer into more perennials. Hostas, lilies, ornamental grasses, and irises all benefit from careful division this time of year. Using a spade or small shovel, lift the plant from the ground, being careful to damage the root ball as little as possible. When the clump is out of the ground, you can then use a garden knife or spade to cut it into smaller pieces. If the plant is too large to heft all at once, some plants are amenable to rougher handling — just use a shovel to cut straight down directly into the plant where you want to divide it, and then pry out the smaller chunks. The plant will sustain some damage, but not as much as your back will if you try to lift a massive, waterlogged root ball. Then, replant the smaller divisions as soon as possible to reduce the chances of shock.

Add New Plants 

Variety of chrysanthemums in evening sunlightIn addition to dividing your already existing plants, August is ideal for planting new perennials and shrubs. Planting now allows plants to invest more energy into healthy root growth during the cooler, moist weather of fall, and good roots means stronger plants. Species that do well getting planted in late summer include hydrangeas, daylilies, sedums, ornamental grasses, peonies, and bearded iris. Just be sure to keep them well watered (especially if it’s still scorching hot outside), so that the roots are able to grow deep.

It’s also probably time to allow your summer annuals to go quietly into the good night. August is a great time to replant your planters and the areas of your beds that need seasonal pops of color. Snapdragons, Dianthus, Pansies, Croton, and Flowering Kale are great additions to any garden, as well as the ubiquitous Chrysanthemums that start showing up everywhere this time of year in New England. (There’s a reason for that: they are sold in bud or bloom so they add an instant burst of color, they’re cold hardy, and as an added bonus, they attract helpful pollinators.)

Repot Houseplants

Hands pulling a plant out of its potIf you have houseplants that vacation in the yard during the summer, now is a good time to see if they need repotting. They’ve probably added a good deal of growth, and that could mean their roots need more room. One way to check is to look at the drainage hole at the bottom of the pot. (If there isn’t a drainage hole, ADD ONE. Plants need drainage, or else you’re encouraging rot and disease.) If roots are growing out of the bottom, or you can see a tangle of them through the hole, it’s time for a new home. Replanting now gives houseplants time to adjust to the stress of repotting before cooler weather sets in and additionally stresses them. This has the added benefit of getting rid of potting mix that may have become a cozy home for insects and other pests that you don’t want to bring back into the house as well. 

Things You Should Rethink

"No" symbol over hand pruning a shrubWhile you’re doing all this work outside, it will be tempting to fertilize and prune, just to cover all your bases. Feeding the plants you just abused feels right, but it would actually encourage growth that probably won’t be able to survive the winter. Stop feeding roses, trees, shrubs, and the perennials that you’d like to come back strong next spring, and give them a bit of toughening up as training for the long winter.

As for pruning, the same advice applies. Few plants are pruned this time of year because pruning encourages new growth that doesn’t have time to harden off before winter. It’s fine to thin out trees and shrubs of deciduous and evergreen varieties, and you could cut back the twiggy summer growth on osmanthus and yews. But avoid pruning any spring-flowering species at all costs, as you could be cutting off the parts where the plant is staging next-year’s blooms.

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