University of Vermont Extension 
Department of Plant and Soil Science

 Summer News Article


By Dr. Leonard Perry, Extension Professor

Lisa Halvorsen, Extension Associate Professor
University of Vermont

"A" is for August, a time for looking ahead to autumn...and for assuring a sufficient supply of water to plants, actively weeding the garden, and aerating and dethatching lawns to promote root growth. It's an appropriate time to assess both flower and vegetable gardens to see what performed well and what additions and changes need to be made. Annuals also need to be deadheaded to encourage continuous bloom.

By August, some of your spring-planted crops may be history. In the first part of the month you can put in new plantings of peas, lettuce, spinach, beets, cabbage, kohlrabi, and kale along with late season perennials like sedum, coreopsis, and phlox.

Seeds need to be planted deeper than you did in spring as the moisture level in the soil is lower. You also will need to be more vigilant about mulching and watering as young seedlings need sufficient moisture to grow well. Your crops will benefit from an extra application of nitrogen fertilizer about halfway though the maturity cycle.

Don't expect as prolific a performance from your second plantings as crops planted in May and June. However, you should be able to get a decent harvest before a killing fall frost.

Pay attention to the rest of the garden, too, checking for insect pests such as squash vine borers on vining crops; Japanese beetles on peas, beans, and flowers; and slugs everywhere. Removing foliage from early garden crops, such as peas, can promote healthier plants as aging foliage can harbor plant diseases.

August is also a good month to take a good hard look at your vegetable and flower gardens. What crops did well? Which should you try instead next year? Is your perennial garden overgrown? Do some plants need to be relocated because they are too tall or the wrong color for that particular bed? Take notes so you can correct the problem. Don't depend on your memory. Write it down.

You may notice a dust or talcum-like powder on your roses, phlox, or lilacs this month. That's powdery mildew. It's a fungal disease, that while unsightly, causes little damage to ornamentals and garden plants.  Applying a fungicide now will keep the disease from spreading. It will not, however, get rid of the problem. If you prefer not to use chemicals, thinning the plants to improve air circulation will help, as will pulling mulch away from roots and stems.

August is a good time to divide and transplant garden irises and daylilies (hemerocallis). By now the fleshy rhizomes (underground stems) of irises and crowns of daylilies have stored enough food to encourage active root growth and successful reestablishment after moving.  You can, however, move them anytime during the growing season.

To transplant, divide the clumps after bloom, leaving at least three to five buds or "eyes" per plant. Check for rot or borer damage and discard these pieces. Replant leaving 18 to 24 inches between plants. Iris rhizomes should be just barely covered with soil. Plant daylilies the same depth as before. Water the transplants thoroughly to get them off to a healthy start.

At the end of the month prune raspberry bushes, waiting, of course, until the harvest is over. Prune out the old canes to make way for the new ones. Do not fertilize at this time as this encourages new growth that will only be killed by fall frosts.

Other August activities: reseed and renovate worn areas of your lawn; can or freeze fruits and vegetables for winter enjoyment; prune climbing roses; take stock of what you might have to enter in late summer fairs.

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