13November 5, 2014

The days are getting colder and your shrubs will soon be entering their long winter nap. Many of your trees and shrubs will benefit from a late fall application of fertilizer. In the late fall, the fertilizer is applied at ½ the regular rate. This allows the plant roots to strengthen, yet doesn’t apply enough fertilizer to promote new leaves or needles on the plant. Any new leaves or needles that come out at this time of the year are likely to be damaged by the winter. Once the fertilizer has been applied, you should add a layer of mulch around the base of the plant. The mulch should be applied on top of the soil to a depth of 3 inches. The mulch should cover the soil out to the edge of the branches of the plant. This area is called the root zone of the plant. What you are doing is covering the roots that supply the plant with water and food. If these roots are damaged by the winter, the plant may not live through the winter. The problem for the roots is that once the soil freezes, the plant is slightly lifted out of the ground. This lifting damages some of the roots. If the soil stays frozen, this is really no big deal. The problem is that there can be multiple freeze and thaw cycles during the winter. Each time the soil thaws; the plant drops back down in the soil. If the soil freezes and then thaws and then freezes and thaws multiple times during the winter, there can be major damage to the roots. In some cases the root damage is so severe that the plant has minimal roots left come the spring. As the plant tries to take up water and nutrients in the spring, the plant can’t do so and the plant dies. The fall application of mulch prevents this freeze thaw cycle from happening again and again. Once the cold eventually penetrates the mulch, the soil will freeze. But if the temperatures rise again, it can take a long time for the warmth to thaw the soil under the mulch. The fall application of mulch prevents this repeated freeze thaw cycle from happening and your shrubs have less root damage. This is why an application of mulch is so important in the fall.

I recommend that you use bark mulch as your late fall mulch. It is easy to apply unless you wait until the mulch is frozen. Many people want to use leaves or pine needles but leaves or pine needles tend to pack down and you lose the insulating effect as mulch. You can use straw or salt marsh hay but come the spring you have to remove it and it can be hard to dispose of the hay. Bark mulch can be used in the spring to mulch your annuals or perennials. In some cases, the bark mulch you use can be left in place and you saved yourself from having to remove leaves, or hay and then mulch with bark mulch.

Fertilizing and mulching your trees, shrubs and perennial beds is something that you need to do to help your plants to survive the winter. Many people did not do this last year and many people had plants that died or had plants that came through the winter with significant leaf damage. You still have time to do this necessary fall chore.

Well, that’s all for this week. I’ll talk to you again next week.

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