Protecting Landscape and Too Much Fertilizer

The Green Thumb

Q: Last year, we lost some shrubs to deer or rodents eating the trunks. I hope I am not too late to do something this year. Is there something I can treat them with to stop the damage?
A: There are many sprays, liquids and powders available at the store and created with home recipes, but all of them require multiple treatments, as they eventually wear off. During the winter, the snow cover may make it difficult to treat the lower parts of the stems where the rodents will be eating, hidden under the snow.

The strongest layer of protection is a physical barrier. Fencing of some kind is best. Wrap a single-trunked tree in a layer of chicken wire or hardware cloth. Chicken wire may have large enough holes to let mice and voles nibble on the bark, so a couple of wraps around the trunk may be necessary. The fencing may need to be raised higher if snow creates an artificial higher ground layer.
If animals are eating the ends of branches, then the sprays work well, but they need to be reapplied during the winter. The spray may need to be applied when the temperature is above 40 degrees F, so that may limit is use.
Q: Some of my houseplants are beginning to look bad. I am doing the best I can to give them light, keeping the soil damp and fertilizing. I have placed some trays of water among the plants to try to keep the humidity up. The one thing I have noticed is that the plants that look the worst also have a white crust on the top of the soil. I don’t know what is making the deposit. I have not seen any insects or worms in the soil. What could be the problem?
A: The white crust is salt buildup, probably from too much fertilizer being applied. The chemicals in most fertilizers are salts. The salts dissolve in water and then move into the plant. The salt that doesn’t make it into the plant moves through the soil in the water. We expect water to move downward in the soil, and it does in the garden. However, in pots, some of the water moves upward, carrying salt. When the water evaporates into the air, salt is left on the top of the soil.
The white crust is letting you know that there is too much fertilizer in the pot. The extra fertilizer salt in the soil that hasn’t moved up to the crust yet has the potential to kill the plant roots. Extra salt that does make it into the plant will travel all the way to the outer edges of the leaves. It will build up at that point and kill the leaf edges. So brown edges are another sign of too much fertilizer.
Using an organic fertilizer may help because of the slow release of the nutrients, but there are still salts that go into the plant. Cut back on the fertilizer applications during the winter when the plants are indoors.
Scrape off the crust and the top half-inch of soil under the crust. Scrape any crust off the sides of the pot. To wash some of the excess salt away, create a fake rainfall for the plant. Put the plant in the sink or bathtub, and run two or three times the amount of water it would take to fill the pot. In other words, a 1 gallon pot would have 2 or 3 gallons of water run through it. This process is called leaching the soil. Once during the winter should be enough.
Email questions to Jeff Rugg at

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