Know when to water; Know when to walk away

By Bev Johnson | The Daily Journal

Published Saturday, August 25, 2007

We have had some rain but it is not nearly enough. You have probably been hitting the iced tea or lemonade more than usual.

Your plants don't have that option. They look to you to give them the proper water. So how can you tell if your plants are dying for a drink. If your Ligularia "faints," that is, falls over, it is desperately calling for a drink.

Other plants may not be as dramatic in their demands. You may see their leaves roll up like a cigar, or their leaves may be yellow with only the veins showing any green. This is because there is not enough water for the transport of food to the leaves.

Plants must have enough water to form a solution with the nutrients before the plant can use the food. That is why you never fertilize a dry plant. The soil needs to be wet first or you risk damaging your plant.

While you should no longer be fertilizing trees and shrubs, you should continue to fertilize your container plants, annuals and actively growing vegetables. Your landscape plants, trees and shrubs, have completed their growth for the year.

Fertilizing them now would make them go into the winter too lush and could cause you to lose that plant.

Strawberries need food now. The recommended ratio is 5-10-10.

Too much nitrogen makes leaves rather than fruit. Do give any plants fertilized lots of water. Don't cut any perennials down now.

Cut leaves down only on iris or peonys if they are being moved. Even if they look terrible, leaves are storing food for next year’s bloom.

A soil probe costing between $30 and $200 is a good investment to really determine if your trees and shrubs are getting enough water. It will pull a soil core from 6 to 18 inches from the soil.

Another good investment is a soaker hose, especially if you are on water restrictions. It waters the root zone, not the air. A sprinkler can lose half the water to evaporation on a hot day.

Newly planted trees or shrubs, that is within the last five years need more than the usual one inch a week to "live long and prosper." Water until the soil around your trees and shrubs is soggy. Then use your probe to see how deep the water actually went.

Most trees have the majority of their roots in the top 18 inches of the soil. At least the top eight inches should be wet. To determine how far the roots reach laterally, measure the diameter of the trunk and multiply by one foot. A tree five inches in diameter would have roots five feet out from the stem. Mulching a tree or shrub will help preserve the water that it does get.

Hope for a very wet fall to get our mature trees and shrubs through the winter.

Bev Johnson is a master gardener for West Otter Tail County.