9/29/17: In the garden this week


Many native perennials display beautiful fall colors. The short plant with red leaves is sundrops (Oenothera fruticosa), which blooms with yellow flowers in May-July; the taller one is Penstemon digitalis, which has white flowers at the same time.

After several weeks of unseasonable heat and drought, we finally feel a hint of fall today (thought still no rain in sight). Fruits have ripened, but most trees and shrubs are holding fast to their leaves, which for the most part look both green and sad. Some early-turning shrubs and trees are showing color, but the color is subdued. The drought and heat are having an effect.

In the vegetable garden the prolonged heat means that pests and diseases have longer than usual to weak havoc, and fall cool-weather crops are sparse. On the positive side, tomato plants are still producing.

Fall is a good time to plant, especially trees and shrubs (though not as good as spring). But the reason it’s good is the cool temperatures: plants concentrate on growing roots when the soil turns cool, top growth when it’s warm. So far this fall has NOT been a good time to plant, although lots of watering helps.

Fall is a good time for lots of other garden chores, however:

water new plantings this week: there’s been almost no precipitation for the past 3 weeks. In any week in which we receive less than an inch of rain, water all woody plants installed this season or last fall. The soil is very dry, so even perennials planted this spring might be in need of a little extra water. How do you know when we’ve received an inch of rain? I use a highly sophisticated rain gauge–an old yogurt container placed on the ground among the plants. A tunafish or catfood can works equally well. I will water my new trees and the clients’ gardens I oversee this week, and on Sunday I’ll water some of the perennials I put in this past spring.

practice good horticulture with warm-season crops such as tomatoes, peppers, squash, eggplant, beans, corn, and cucumbers. This is particularly important as the season winds down. Monitor for insect eggs and larvae and remove them before infestations become serious. Throw out infested or diseased plants to prevent the spread of disease (do not compost diseased or infested plant material).

— as tomatoes ripen their fruit, cut back on watering to avoid split fruits: provide no more than an inch of water per week. (If it rains, don’t water.) Keep removing suckers. Look at this post, this one, and this one for basic information about growing tomatoes. And keep picking: don’t let the fruit rot in the garden.

continue to plant cool-weather crops such as lettuce, arugula, spinach, mustard greens, and peas for fall harvest. I’m betting on a war fall.

extend a garden bed or start a new one (it’s always a great idea to eliminate some lawn): mow the grass very short, then spread a 3-4” layer of cedar or hemlock bark mulch over the area to kill the grass. You’ll be able to plant right through the mulch and thatch next spring. You can scatter seeds there now as you collect them.

collect seeds. Seed of purple lovegrass and of little bluestem is ripe, as are seeds of nodding joe pye weed, penstemon, prairie onion, and monarda. Milkweed seed needs to be collected almost daily. I try to harvest just when the pods split open so I can easily separate the seeds from the down.

— follow a sustainable lawn care regimen: if you feel you must fertilize your lawn, best practice is to give it no more than two applications of slow-release organic fertilizer each season, around Memorial Day and Labor Day. Now that the nights are cool, it’s a good time to reseed bare areas. But be sure to water newly seeded areas frequently: grass seed will only germinate if kept moist, so give seeded areas a light sprinkling several times a day. If you have a place where grass won’t grow, plan to plant something that will, like shade-loving native perennials. Let the grass grow at least 3″ tall for maximum photosynthesis. Lawns certainly do not need water. And always remember: the more you water, the more you’ll have to mow!

— plan for next season: Do it now, while the garden is still growing. Notice things that did great and things that didn’t, make lists of areas you want to improve, areas of lawn you could get rid of, places that are getting sunnier or shadier and need new plantings to suit.

Enjoy the garden this week! Keep a lookout for fall monarch migration (they’re going south). Will they find nectar for the journey in your garden? If not, plant some asters!


New England aster beats most other plants for attracting pollinators in fall.


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