Regional Gardening Reports :: National Gardening Association

New England

July, 2010
Regional Report

Keep an Eye Out for the Columbine Sawfly

Look for little green worms gobbling up the foliage of your columbine plants. These are the larvae of the columbine sawfly, an introduced pest that was first found near Ottawa, Canada in 1964. By 1985 it had made it to western New York state. It has continued to expand its range since and is now found throughout our region. The larvae feed for a few weeks beginning in in late spring, then drop to the soil to pupate and emerge as adult flies. Because the worms are almost the exact color of the leaf and they feed starting at the edges of the leaf undersides, it is easy to overlook them until they've eaten most of the leaves. There are multiple generations, so you need to watch for them throughout the summer. Control a light infestation with hand-picking. If your plants are heavily infested, you can treat with insecticidal soap, spinosad or pyrethrin. The columbine sawfly only attacks columbines, so you don't need to worry about it feeding on other plants.

Water New Plantings Regularly

Remember to keep new plantings watered regularly throughout their first season as they become established. When you do water, put down enough water to soak the entire root zone, then let the top few inches of soil dry out before watering well again. Keep in mind that brief summer thunderstorms may drop a lot of water, but often so quickly, it runs off and doesn't soak deep into the soil. So don't assume that Mother Nature watered sufficiently; check soil moisture by digging down a few inches to check.

Cut Back Early Bloomers

When early bloomers like catmint (Nepeta), candytuft (Iberis), moss phlox (Phlox subulata), maiden pinks (Dianthus deltoides), rock soapwort (Saponaria) and Hungarian speedwell (Veronica austriaca teucrium) finish flowering, shear them back by one-third to one-half to improve their appearance and promote possible re-bloom. Cut plants like hardy geraniums, Jacob's ladder (Polemonium) and perennial salvias back to their clump of basal foliage after their first flush of bloom is past.

Sow Dill and Cilantro

Continue to make small, successive plantings of dill and cilantro every 10 to 14 days so you have a continuous supply of fresh leaves throughout the summer. But be sure to let some of these herb plants flower and set seed for harvest as well. (The flowers are also great for attracting beneficial insects to the garden.) To dry the seeds, cut the entire flower head and hang it upside down, enclosed in a paper bag. The harvested seeds of cilantro are called coriander- don't ask me why!

Avoid Tomato Troubles with Consistent Soil Moisture

Dark, leathery spots on the blossom ends of tomatoes, peppers, cukes, melons and squash is a physiological problem called "blossom end rot." While it's caused by a calcium imbalance in the plant, the root cause is uneven soil moisture that keeps the plant from taking up this important nutrient. So keep up with watering and use mulch to help keep soil moisture consistent.


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