8/18/17: In the garden this week


The perennial border displays its brightest colors in August. Rudbeckia subtomentosa, Agastache foeniculum, and Hibiscus mosceutos vie for attention amid the greenery.

August may be a dull time of year, but not in the garden, when the floral display is at its height. This is the time to sit on the patio with a cold drink and enjoy the fruits of your labor. But while you’re out there, here are a few things you could be doing:

water new plantings: I watered my young trees last Sunday and will do so again this week unless we receive considerably more rain tonight and tomorrow: this morning’s downpour amounted to just over half an inch, and I aim for an inch to an inch and a half per week. Remember that perennials and woody plants that you planted this spring or last fall need supplemental water during dry periods throughout this growing season. The rule of thumb is at least an inch of water per week for newly installed plants. In dry weeks throughout the growing season (weeks with less than an inch of rainfall), you need to water all plants installed this spring or last fall. Trees need supplemental watering even longer: the rule of thumb is one year per inch of trunk diameter. How do you know when we’ve received an inch of rain? You can make a highly sophisticated rain gauge–an old plastic container or tin can placed among the plants. I total the weekly rainfall and decide whether to water my new trees or my clients’ new plantings each week.

— if you intend to plant a second crop of cool-weather vegetables, you should be starting seed. Water the vegetable garden deeply during dry periods, particularly when the weather is hot, and watch carefully for pests and diseases. Removed diseased plants promptly to prevent spread. Continue to remove the flowers from basil plants as they form. And pick those zucchini before they reach the size of baseball bats!

— continue to properly tie, stake, and prune your tomato plants. Most tomato cages are much too small: the plants outgrow them before they start to bear fruit. And unless tomato plants are properly pruned, by pinching out the suckers, they will be so bushy that they’ll be especially susceptible to fungus infections like verticillium wilt. You’ll find general guidelines for growing tomatoes here and specific watering instructions here.

—  do not plant ornamentals like perennials and shrubs until the weather turns cool in fall. During hot weather, plants put their energy into top growth and blooming rather than growing new roots. If you do continue to plant, water very thoroughly and keep an eye on those new plants. They will need extra water during dry periods, as explained above.

it’s also a bad time to fertilize your lawn or to reseed bare patches, no matter what your lawn-care service tells you. Lawn grasses are adapted to much cooler summers than we experience. All they want to do during this time of year is go dormant, so they can’t use any extra nutrients. Here’s a suggestion: don’t feed at all this year. The lawn will look just fine. Or wait until Labor Day and use one application of a slow-release organic fertilizer. Avoid pesticides, fungicides, and herbicides. Pesticides kill butterfly and firefly larvae and native ground-dwelling bees as well as “bad” insects. And garden chemicals are not so great for kids or pets either; common herbicides, in addition to killing butterfly host plants like violets, are carcinogens. Best to avoid them.

— this is a good time to prune woody plants. You want to prune when the plant is relatively quiescent—when it’s not using so much energy growing, flowering, and fruiting that it has little to spare to heal a wound. This quiescent period occurs between now and leaf drop (abscission) in fall. Basically, when you see that the plant has finished fruiting and that it has formed next year’s buds, but the leaf color is not fading yet, you have a window of time for pruning. Of course, you should prune diseased or injured plants at any time as well as remove any safety hazards, such as overeager shrubs that block sidewalks or diseased trees that might fall down.

do not deadhead your perennials. Seeds represent winter food for birds and other creatures and new plants for you. Collect seeds as they ripen, and store them in a cold place (such as an unheated garage) for next year’s planting, or simply scatter them on the ground where you want them to grow. Do deadhead potentially invasive plants like butterfly bush, miscanthus, and pennisetum grasses however.

Enjoy the garden this week!

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Nodding pink onion (Allium cernuum) is not flashy, but it’s nonetheless a star of the August garden. This is a front-of-the-border plant that thrives on full sun and dry soil.


Rudbeckia triloba has just started blooming. I’m always very happy to see it. The flowers are just so cute.


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