5/5/17: In the garden this week

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Chokeberry (this is black chokeberry, Aronia melanocarpa) is in full bloom now. In August, it will produce large black berries for birds (and jam); in fall, the foliage will be brilliant orange and red.

Planting season is in full swing, and I am grateful for this very rainy day. The ground was getting too dry to plant without watering first, and I’m in the middle of a very busy planting season. I like to finish planting perennials, grasses, and shrubs before Memorial Day, although you can plant later if you can water frequently. Roots grow best when the soil is cool.

You’re probably thinking about preparing your yard for outdoor living: setting up the patio and grill, uncovering the pool, planting ornamentals. Give some thought to sustainability as well as to livability. Consider planting native perennials instead of annuals (less watering, less work every spring); using fewer chemicals on the lawn (less expensive, kinder to the environment); welcoming pollinators and birds (planting natives, avoiding pesticides). Maybe there are some areas of lawn that could be replanted as flowers or vegetables. Maybe you can water less often this season.

In addition, here are some seasonal gardening tasks you might do this week:

water new plantings: Rainfall totals are finally normal or even a bit above, at least in the short term. We’ve received approximately an inch and a half of rain today so far, so no need to water. But always water well after planting to settle the new plants in the ground, and check back here weekly for updates: In any week in which we receive less than an inch of rain, water all plants installed this spring or last fall. 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.

plant trees and other woody plants. Don’t wait too long—the earlier you plant, the more time trees and shrubs will have to establish before the weather really heats up. Same goes for perennials and grasses. The earlier the better.

provide prophylactic care for trees. Several native tree species are at great risk of succumbing to invasive insect infestations. Hemlocks should be sprayed with dormant oil (which is not a pesticide) in early spring and early fall. Ash trees should be treated for emerald ash borer. Consult a qualified arborist if you’re not sure if you have hemlocks or ashes; he or she can then recommend the best treatment options.

— continue to start vegetable seeds indoors. You’ll find a schedule here. Get the vegetable garden ready for the coming season by weeding, raking the soil smooth, and adding compost or well-rotted manure. Compost can simply be spread on top of the soil; manure should be mixed in, and make sure it’s not fresh manure. Once the soil is prepared, you can plant seeds of cool-weather crops such as mesclun, spinach, arugula, peas, and beets in the garden. Do not set out warm weather crops like tomatoes and eggplant for another few weeks.

—  After cleaning up the perennial garden, continue to plant perennials and to divide and move them as they emerge. The earlier you divide or move perennials and grasses, the quicker they will establish. Even finicky, hard-to-divide plants will respond well. And it’s much easier to divide and replant a few plants at a time than to dig up an entire bed.

it’s much too early to feed your lawn, no matter what your lawn-care service tells you. Wait until Memorial Day, and then use a slow-release organic fertilizer. Or best of all, don’t feed at all this year. The lawn will look just fine. Remember that 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 are carcinogens. Best to avoid them.

— Support a local farmer by joining a CSA (community supported agriculture) this season. CSAs allow you to support small-scale, sustainable agriculture and help limit the environmental effects of factory farming. You’ll also find that the produce tastes much, much better than what you buy in the supermarket. For the past 5 years or more, we have joined Hesperides Organica, a family-run farm located in Hawthorne, NY. They deliver weekly to various locations in Bergen County.

Enjoy the garden this week.

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Lovely foamflower (Tiarella cordifolia) is in full bloom now in my garden.

 

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Emerald ash borers

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The tallest tree in my backyard miniforest (center left, not totally leafed out in this photo, which was taken in early May 2008) is a white ash (Fraxinus americana).

Our native ash trees are under severe threat from an Asian beetle, the emerald ash borer, that arrived in Michigan in 2002 and has since spread throughout much of the country (but not yet to Bergen County, although it has been found both north and south of us). Relatively harmless to healthy trees in its native habitat, the beetle kills our native ashes in 3-4 years. Read what to look for and some ways to prevent infestation here.

Today’s Science Times has an article on current efforts to use the trees’ natural defenses to protect them. Plants are always fighting threats from funguses, insects, and other predators, and they have many defenses against attack (ever been stuck by a thorn?). In Asia, ash trees have evolved specific defenses against the emerald ash borer, and scientists in this country have been studying how they work. It turns out that Asian ash trees make specific chemicals to fend off the borers, and although American ashes produce some of the same chemicals, they may not make them fast  enough, or in the right combinations, to defend against the borers.

But researchers have recently found that a plant hormone, methyl jasmonate, acts as a kind of alarm, prompting the entire tree to produce chemicals that kill the borers. And when American ashes are sprayed with this hormone, they too produce chemicals that kill the borers. The effect is as great as a strong dose of insecticides.

The next step would be to develop a line of resistant American ash trees, trees that can mobilize natural biological responses as fast as the Asian trees can. Until that time, monitor your ash trees for signs of damage. The most important and earliest would be dieback in the crown of the tree. If you see that kind of damage, notify the US Forest Service. And don’t move firewood: that’s a major way that the borers are spread.