Last Summer’s serious drought has already killed some plants and injured countless others. In the vicinity of Boston, practically no rain worth mentioning fell during July and August, some places having little or none even in June.
The deficiency in rainfall on September first, was somewhat reduced by fast and heavy rains during September – about six incites’ worth, but these came so rapidly that the water did not soak into the soil as it should. Now, as this is being written (late October) there is still a deficiency in rainfall of seven inches, and gardeners can expect considerable injury to woody plants unless soaking rains come before the ground finally freezes this Winter.
Evergreens in particular may stiffer, and, of course, these must be watered thoroughly and frequently before the ground freezes. Deciduous plants, many of them, are better equipped to take care of themselves, but even these may suffer severely this Winter. No one can say how badly off mature trees are right now. They may look all right, they may have dropped their leaves at the normal time, hut the amount of water stored away in their storage organs may not be sufficient to take them through the Winter unscathed. Injury to such plants may be unnoticed until next Spring, after the leaves begin to appear. Then a browning and quick dying of the foliage may be ascribed to a “hard Winter,” and not the true cause – the lack of water during the previous Summer.
Every gardener knows that watering trees and shrubs in the late Fall before the ground freezes is the best possible insurance against injury later on. So is mulching. A thick mulch of any one of a number of materials placed on the ground after it is thoroughly wet, will aid materially in conserving that moisture in the soil, and in keeping the ground slightly warmer, thus allowing the roots to continue their active growth a little longer. This is very much to the good.
There are some shrubs which have withstood the Summer’s rainless period remarkably well. Some of the most outstanding of these might be mentioned, not necessarily because we must plan for future severe droughts in this area, but rather because there arc always some dry spots where special drought resisting plants should be used. It is too soon to list the trees unaffected by the drought, since injury to many of these may not be noticeable until the next Spring, but some genera contain several species which have done well. Such would be the oriental quinces, Chaenomeles; the brooms, Cytisus: the indigo, Indigofera; privets, Ligustrum; matrimony vines, Lycium; ninebarks, Physocarpus; buckthorns, Rhamnus; sumacs, Rims: and locusts, Robinia.
Then there are individual shrubs which have done very well. The Amur maple, Acer ginnala, is an excellent small tree, noted for its dense growth and vivid scarlet Autumn color. Not all of the barberries have prospered, but the most widely planted of them all, the japanese barberry, can certainly be placed at the top of the list as far as drought resistance is concerned. It has often been said, and justly, that if there is a dry spot in which the Japanese barberry will not grow, it is a waste of time to try anything else. The mentor barberry, Berberis mentorensis, a semi-evergreen, is also in this same group, and might be used more for this purpose.
The Siberian pea tree, Caragana arborescens, and some of its close relatives should be included, for they are used extensively in windbreaks and hedges in the Great Plains areas of western Canada where dry conditions are the rule rather than the exception. They also are very hardy, and withstand very low temperatures for extended periods. The native groundsel-bush, Baccharis halimifolia, the pistillate plants of which are so noticeable in the Fall with their small, thistle-like flower heads, not only withstands dry soil, but salt water spray as well, making it a desirable plant for the seashore.
Another native, the common witch-hazel, Hamamelis virginiana, which is the last of the woody plants to bloom in the woodlands of the northeastern United States, can be grown in full sun and dry soil. Merely because it is found chiefly in the woods does not mean it cannot be grown elsewhere. Some of the best specimens in the Arnold Arboretum (and they do make splendid specimen) are growing in full sun.
Bayberry, Myrica pensykanica, and the Beach Plum, Prunus maritime, are two more natives for this group, typical of the northeastern United States, and splendid dry soil plants. The bush cinquefoil, Potentilla frulicosa, native from the tops of the Olympic Mountains in Washington clear across the continent to New England, is another. Gardeners tend to overlook this plant, for it grows only about three feet tall and has small yellow or white flowers 1%” in diameter, but it certainly merits consideration. It is not susceptible to any serious insect or disease pest and blooms continuously from mid-May throughout the Summer. No, it is not conspicuous, but it is dependable!
The Scotch rose, Rosa spinosissima, and Virginia rose are both natives of North America and withstand dry soil conditions as well or better than most of the other roses. The low dwarf gray willow, Salix tristis, is still another poor soil plant, seldom over 1 1/2′ high, but with excellent light gray foliage, and good for planting on banks where soil erosion is a problem.
Finally, some of the junipers merit consideration as dry soil plants, being among the few evergreens which can be considered in this category. The common juniper, Juniperus communis, is one, together with the native red cedar, J. virginiana. The creeping juniper, J. horizontalis, and the shore juniper of Japan, J. conferta, are two other low, creeping plants that aid in covering the bare spots on poor dry soils, neither one growing over 1 1/2′ in height.
These then, are a few of the shrubs which have done well in the drought of 1949, and which can always be expected to do better than other plants on dry soils. Many other plants did well, too, during the past Summer, but these mentioned have proved themselves time and again as among the first. to warrant consideration for growing in places where dry soil conditions are prevalent.
