Moisture Stress Cuts Both Ways


If you are noticing plants that have brown, crispy leaf margins and even yellowing leaves, they are probably experiencing moisture stress.  That means not enough moisture is getting to the leaves from the root system.  This could be because the soil is dry.  Or it could be because the soil stayed too wet and caused some roots to rot so that they cannot carry enough water.  It could have been too wet at one time and too dry now!

New trees and shrubs in particular will be suffering in the heat, so don’t neglect them.  Sure, we had a lot of rain in the spring — but that may not help your plants now.

We had several episodes of heavy rains that caused water to stand for prolonged periods in some areas.  This may have caused some root rot.

For sure, the wet weather caused many plants to leaf out very heavily because there was so much moisture available.

Now we go into periods when it is extremely hot and dry, and plants may start shedding leaves because they can’t support so many during the heat.

But sub-soils may still be holding a lot of water.

What to do?

First, feel the soil.  Poke a screwdriver down so you can see if the soil is dry or wet (you may be old enough to remember using a dip stick to check the oil level in your car — same idea).  If it is wet DON”T WATER and check again in a couple of days.  If it is dry, water slowly and deeply, then check again in a few days.

Here are some rules to follow:

  1.  Older, established trees and shrubs need very infrequent watering.  They can go for weeks without water, if they are otherwise in good shape.  When they need to be watered, water slow and deep.
  2.  Newly-planted trees and shrubs cannot go even a couple of days in hot weather without supplement water.  They have limited root systems and cannot search out water sources.  Feel the root ball of the plant, not the surrounding soil, to determine when it needs to be watered.
  3.  The smaller the plant’s root system, the more often it will need to be watered.  Small pots and hanging baskets will probably need to be watered every day, while larger plants can go much longer without supplemental water.
  4.  Bark mulch in your flower beds and around trees and shrubs will conserve soil moisture and reduce your water bill.  BONUS:  Mulch also deters weed growth.
  5. Deep watering — GOOD!  Light sprinkling — BAD!

You notice, this advice does not include a calendar telling you when to water.  How often you water and how much depends on the temperature, the soils the plants are in, the humidity, the wind and many factors that are constantly changing.  You cannot set a sprinkler clock and forget it.  You must investigate by poking in the soil.

It takes a little practice, but you can learn to tell when your plants need to be watered!