Dry weather imperils plants on Martha’s Vineyard

Premature coloring of foliage often indicates plant stress, as in this Euonymus alatus. — Photo by Susan Safford

Ordinarily, euonymus foliage starts to turn color towards the end of September, earning its common name, burning bush. The shrub by the side of the highway shown here has been turning since early August, way too soon. The premature coloring is a signal that the plant is stressed. If the dry spell continues, many more Island trees and shrubs will become stressed as well, in less than optimal health going into winter.

Most woody plants benefit from mulches of composted organic matter. Scatter a top-dressing of low number organic fertilizer on the bed surface, and then cover it with the mulch: two to four inches deep under the drip line or covering the root zone of individual plants, making sure that there are no mulch “volcanoes” or material in contact with the trunk. Drought watch includes supplemental watering for trees and shrubs that have been planted or transplanted within the last three years.

Where woody plants have been planted in shrub beds (“shrubberies”), edge and weed the bed, then mulch it with composted organic matter. It will look nicely tidied up. As above, a top-dressing of low number organic fertilizer laid first ensures that the biology in the soil is taken care of.

It has been tremendously dry; until this week there’s been no proper rain since August 6/7. Hurricane Irene came and went but left the rain elsewhere.

At this time of year the sun’s rays have a different make-up and quality than several months back. At the vernal equinox in March in the northern hemisphere, the sun’s light starts to take a shorter, more direct path through the earth’s atmosphere, because the earth’s axis tilts the northern hemisphere directly at the sun. This short path gives light its blue quality, setting off myriad natural processes in the cells of living organisms: for example, prompting buds and leaves into growth.

Now, as we approach the autumnal equinox, our part of earth is tilting away from the sun. Light is electromagnetic radiation. The path the sun’s radiation takes to reach us before it strikes the earth is longer, the resulting spectrum redder. Energy arriving from the sun as infrared light warms things, such as water and soil, penetrating the ground, prompting root hairs to expand and grow, but hastening drying too. Putting down soil food and mulch now is preparing for winter and for the aboveground growth that happens next spring.

Brix levels

An interesting piece in the September issue of “The Avant Gardener” concerns enhancement of Brix levels in vegetables. As is done with grapes in wine-making, a refractometer may be used to measure the sugars in juices of plants, which are expressed in Brix units. “Recently some organic [growers] have begun to check the Brix levels of their crops to see just what influences their flavor. Apart from varietal differences, “cultural practices…can effect Brix readings. ‘Growing for Market’ reports that a large community garden in Seattle found that ‘the Brix levels of just about every vegetable rose each year’ as they added more organic matter to the soil as compost and mulch.

“…foliar feeding can also raise Brix levels. Fish and seaweed products appear to be the most effective, supplying a wide range of trace nutrients and growth-promoting compounds. High-mineral rock dusts added to the soil also enhance plant vitality and taste. Pest resistance increases along with rises in Brix: a grower in Washington observed that [Colorado potato beetles] stopped feeding on potato leaves when their Brix rose to 15.

“A Brix of 10 is considered average for many crops, but organic growers are said to be achieving 24 Brix sweet corn, 18 Brix peaches, and 28 Brix strawberries.”

In the Garden

Research and order seed now for cover crops for the vegetable garden. Nowadays, much more than the longtime standby, winter rye, is available for the cover cropping. Purchase locally or by mail. Seed vacant areas as they are freed up from the previous crop. With some of the above Brix information in mind, consider ways that Brix levels of future crops might be increased. Confirming the garden’s current status with a soil test would be a good idea.

Collect and compost garden debris: if the garden has cleaned-out empty areas, you could experiment with sheet composting on the ground. Sheet composting involves spreading a layer of compostable materials on the ground where it is to be utilized. Sometimes it is loosely scattered with soil and left to decompose over the winter. Some of the mineral rock dusts might be applicable, or seaweed gathered from the tide line.

Plan for garlic planting later in the fall. The plants respond to fertile, compost enriched soil and there is still time to prepare the bed. Order seed garlic now, if you have not done so already. There is also time to plant a few quick-growing cool weather crops: lettuce and other salad greens, spinach, beets, and carrots. Some positions in your garden may be more propitious than others for extending the season.

Order spring bulbs. Chipmunks, although “cute,” have become a common pest all over the Vineyard. They join squirrels, voles, and mice in causing headaches when it comes to tulip and crocus bulbs. If you have planted bulbs that failed to appear, rodents may be the cause. Plant them buried in wire baskets. They protect the bulb but let it grow through, and can be made or purchased.

Fall Plant Sale at Polly Hill

Saturday, Sept. 10, from 10 am to 2 pm, arboretum staff will be on hand to answer questions and offer advice. They have chosen trees, shrubs, and perennials, including many Island natives, which are suitable for our Vineyard climate.