3/20/15: In the garden this week


Arrowwood (Viburnum dentatum) is a multistemmed shrub with very straight stems (like arrows) and deeply toothed leaves (dentatum). It’s common in wet places throughout northern New Jersey, and it’s highly susceptible to a newly arrived insect pest, Viburnum leaf beetle.

Last night I attended a highly informative meeting of our local Bergen-Passaic chapter of the Native Plant Society of New Jersey. The topic was new pests of native plants, and I learned about a serious threat to our native viburnums (see photo and caption above). The viburnum leaf beetle can kill a healthy plant in two to three years by defoliating the plant in spring (larval feeding) and in summer (adult feeding). Arrowwood grows wild in Bergen County in the Celery Farm, the Thielke Arboretum, and in other wet places. The first chore on the list for this week is a way to help eliminate it:

— check stems of native viburnums, particularly V. dentatum (arrowwood), V. nudum (possumhaw), V. trilobum (cranberry bush), and V. acerifolium (maple leaf) for egg cases, which look like this:

The twig at the top of the photo shows egg cases of viburnum leaf beetle; adults are shown below. Photo from http://ohioline.osu.edu/sc195/013.html

If you see the egg cases, remove and discard the twigs. The larvae will emerge when the shrub leafs out in mid- to late April, so you have a few weeks to check the native viburnums in your area. (Do not clip shrubs in public areas without permission!)

The remaining chores are all more pleasant:

order your perennials and woody plants now to get the best selection. (Most local nurseries sell only a very few native species, so I rely on mail order and on specialty nurseries that are up to four hours away.) If you wait until it’s time to plant, nurseries will be sold out of many species.

— buy your vegetable seeds and start them indoors according to this schedule so the seedlings will be ready for spring planting. It’s time to start tomatoes!

— as soon as the ground is bare of snow and not too wet, direct sow seeds of early greens such as lettuce, spinach, arugula, mustard greens, and mesclun mix, plus peas and radishes. They’ll germinate and grow slowly at first, but with any luck you’ll have fresh salad greens in about 6 weeks. Sow a new crop every two weeks to ensure a continuous supply of spring greens until the weather heats up.

— once you can explore your entire property, evaluate the winter’s damage. Don’t remove dead wood or broken branches unless they pose hazards to people or property, because they might be supplying food or shelter to winter-weary creatures, but see what will need doing. How much mulch will you need? Will your evergreens need spring pruning to remove winter damage?

— it’s not too late to extend a garden bed or start a new one, and it’s always a great idea to eliminate some lawn: spread a 3-4 inch layer of cedar or hemlock bark mulch over the area now to kill the grass. You’ll be able to plant in April or May.

— finally, and most important, monitor your garden for bird activity. You should be seeing lots of it, as spring migrants arrive and winter residents continue to forage and begin to build nests. If you’re not seeing this, maybe your garden lacks winter food. Does your garden feed birds year-round? I’ve still got seeds of ironweed and Rudbeckia as well as leaf litter and dead wood for the birds to search for insects. If you’re not seeing birds, consider what steps you can take this season: for example, plant native perennials, stop pruning dead wood quite so aggressively, stop using pesticides on your lawn.

Yes, it’s snowing again. But it’s bound to melt soon.

My latest “Backyard Environmentalist” column, about gardening for wildlife, is on the North Jersey website.


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