In spite of balmy temperatures this week that prompted some crocus, jonquil and hyacinth bulbs to start growing as if it were spring, early November marks the start of formal winter preparations for the Washington area garden. It's what you do for your shrubs and trees for the next six-plus weeks that will largely determine the death or survival of the landscape over the upcoming winter. The time to save the garden is now.
To put things in perspective, you need to consider recent events with your shrubs and trees. The change occurred some two weeks ago when feeding roots launched their water absorption program. Day by day, large amounts of water have been taken up by the roots and stored in reservoirs throughout the trunk.
This absorption process will continue until mid to late December when the ground freezes and water is no longer available to the roots. After that, the plant's survival depends entirely on maintaining an adequate supply of water to the branches, limbs and twigs of deciduous plants or the needles of evergreens.
Every time the wind blows, the plant loses water; if the plant runs out of water at any time over the winter, it is vulnerable to dieback, a disease characterized by a dying backward that starts with twigs and branches. Should dieback occur in January, it would destroy most of the plant by March.
Your first priority is to start soaking the roots of your shrubs and trees. Soak once, twice or three times a week until the middle of December. Don't bank on November rainfall to solve your plant problems. Average November rainfall is a scant 2.82 inches, hardly enough to keep trees and shrubs alive over the winter. Remember that water is much, much cheaper than buying replacement plants next April or contracting to have dead trees removed before they topple on the house.
Don't overlook shallow-rooted shrubs, especially azaleas, mountain laurels and rhododendrons, which have large leaf surfaces to lose water to winter winds; these shrubs must be soaked regularly for the next six weeks to minimize chances of dieback. Arborvitae, hemlock, juniper and fruiting fig trees have similar requirements.
Organize the soaking of shrubs and trees. If you have soaker hoses, run them down one side of your shrubs and up the opposite side. A partly open faucet will provide a constant flow of water without causing runoff.
Use oscillating and impulse sprinklers to soak roots of large trees. Set up sprinklers so water is applied to the dripline, not to areas near the trunk. Feeding roots will only be found at the dripline.
A second priority is the application of sealants to shrubs and trees to reduce the loss of water to the wind. Known as antidessicants, these products provide a protective film over needles, foliage, limbs and branches to reduce the transpiration of water. Unfortunately, some academic horticulturalists once branded the products as useless, but their theories have been disproved in recent years. Today, nurseries and commercial greenhouses nationwide rely on the products.
Among the antidessicants commonly available at garden shops are Forever Green, Foli Guard, Vapor Gard, Wilt-Pruf and Winter Shield. Try to apply them in the next week or two while temperatures are mild. Temperatures must stay above 40 degrees for 24 hours following the application, with no rain. Apply the antidessicants to the foliage and limbs of shrubs and trees and to the needles of evergreens. One application will protect plants for the entire winter.
Third, if mild temperatures continue, spray superior oil to kill overwintering eggs of mites and scale. Again, temperatures must stay above 40 degrees for a full 24 hours after the application. If you don't apply it now, you'll have another chance next March before leaves break.
The only products now qualifying as superior oil are Rockland dormant oil and Security dormant oil.
In both cases, use 5 tablespoons of the oil for every gallon of water. Use a hose-end sprayer if you wish; otherwise use a hand-pump sprayer. Plants to be sprayed include arborvitae, ash, bittersweet, cotoneaster, elm, euonymus, flowering fruit trees, hackberry, hawthorn, hemlock, lilac, linden, oak, poplar, sweet gum, tulip tree, willow and yew. Pines (excluding the Japanese umbrella pine), spruce (excluding the blue spruce) and maple (excluding sugar and Japanese maples) should also be sprayed. Check the label for other plants that shouldn't be treated with superior oil.
Incidentally, the same unsulfonated oil can be applied to gypsy moth eggs next March to reduce the l988 population. If you had gypsy moths last summer, contact a tree company over the winter to have superior oil applied to your trees in mid to late March before leaf outbreak occurs.
Finally, you can apply lime-sulfur under the same temperature conditions to stop scale on apricot, beech, black walnut, fir, hickory, juniper, Japanese and sugar maple, peach, umbrella pine, yew and cryptomeria. Refer to label directions for mixing.
Other priorities for the weekend: Resurrect your amaryllis tuber now so it flowers for Christmas. If you don't have one, head for the garden shop and bring home a few of the tubers, most of which will yield 7-inch flowers all winter long.
With the old tuber, bang your fist on the bottom of the old pot so the tuber and soil comes out in a ball. Massage the old soil so it breaks away, then discard it. Measure the diameter of the tuber and use a plastic pot that is two inches wider than the diameter of the tuber. Strew clay shards at the bottom of the pot, then fill most of the pot with your standard 1-1-1 dry mix (equal amounts of milled sphagnum peat moss, perlite and vermiculite), to which you've added a teaspoon of pulverized limestone.
Scoop a little soil from the pot, placing the tuber one-third in the soil and two-thirds out of the soil. Using lukewarm water, apply sufficient water to the soil surrounding the tuber to wet the soil thoroughly; let it stand in the sink to drain for 15 minutes. Make certain the tuber is in firm contact with the soil by pushing against the top of the tuber. Move the pot to a corner of a room where there is indirect light or to a closet shelf where there is some indirect light. The amaryllis stays there for the next two weeks pending the start of fall growth.
If you find "offshoots" when you repot the old tuber, pot each baby tuber in its own 3-inch plastic pot in the same 1-1-1 mixture. Move the watered pot into full direct sunlight, then grow the plant nonstop for the next two-plus years. We'll have more on these baby amaryllis in the next few weeks.
Add lime now to shrubs that will need a high alkaline soil pH next spring. This means arborvitae, boxwood, privet (ligustrum) and taxus (yew) need ground limestone now since it will take six months for the calcium to adjust the pH come next April. A few handfuls of lime applied to the dripline, scratched into the top inch of soil, will do. If plants are within three feet of a concrete source (foundation, sidewalk, etc.), there's no need to lime the plant on the side nearest the concrete. These plants really need a soil pH in the 6.5 to 6.8 range for optimum growth.
Acidify the soil where acid plants are exposed to lime leeching out from concrete sources. This applies to azalea, rhododendron, holly, juniper, laurel, pine and spruce growing within three feet of the foundation. Use iron sulfate (also known as ferrous sulfate) to acidify the soil now so the pH will be in the 4 to 5 range by next April. Here is how to apply:
Imagine standing in place of the azalea near the foundation. Face the foundation. Spread your arms on both sides, then bring them together in front of you. This half-circle is where the iron sulfate should be applied to the dripline of the azalea. Plan on applying one-third of a measuring cup of iron sulfate for each shrub, perhaps a half-cup for monstrous shrubs. If the soil is bare, scratch the granules into the top inch, otherwise strew them over the mulch and soak thoroughly. Repeat the iron sulfate application around Mother's Day next year.
Jack Eden hosts "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM).