Issue: January 6, 2001

• Soil needs after 20 years under ivy
• Dethatching lawn

Soil needs after 20 years under ivy

My dad dug out the ivy in our back yard that had been growing for well over 20 years. It was quite a task, and I am sure we will be pulling out roots and regrowths for quite some time. He used nothing but a shovel, a hoe, and I believe he did use some screening to catch some of the smaller roots. I don't know what kind of ivy it was—'just large and green, all year round. He was wondering what nutrients in the soil might now be depleted since ivy was there for the last 20+ years? He does compost in another area of the yard. If he were to add compost soil to the soil where the ivy used to be, would that add any needed nutrients to the soil that might benefit the soil? He would like to plant vegetables where the ivy used to be, but he was wondering what shape the soil might be in after 20+ years of ivy being there. Any ideas of what nutrients the soil might be lacking, if any? Lori

The ivy you described sounds like English ivy. As you described, it will probably continue to regrow from pieces of stem which remained in the ground, not the roots. Over the time it grew on that site, it was extracting minerals from the soil, but then as leaves and old stems died, they composted on that site and returned the minerals to the soil. Nutrients were removed when the living material was taken from the site, but that may not be especially significant. The only way to know what is deficient in the soil is to collect a soil sample, about a pint collected from randomly selected spots over the whole site (to a depth of about 4 inches). Mix these random samples, dry them, and send them to a soil testing laboratory.

It is important that you tell the soil testing laboratory what plants you will be growing on the site. That information will be important as they make their report to you.

Contact your local Cooperative Extension Service for a recommended soil testing laboratory. The Extension Service office also has information to guide you in the collection of the samples and to help you interpret the results you receive from the soil testing laboratory.

Dethatching lawn

When can I dethatch my lawn? I want to have a beautiful lawn this year and learned that the problem last year was the thatch.

Thatch is the accumulation of dead leaves, stems, and roots on the surface of the soil. This layer is a cushion protecting the soil when it does not exceed one-half inch, but when the layer becomes too thick it becomes a problem. It interferes with the infiltration of water into the soil, and it can foster the growth of disease organisms. So, removal of the thatch may indeed be a good idea.

The time to dethatch depends on the type of grass you are growing. The dethatching process damages the grass, so the grass must have time to recover from the injury soon after dethatching. This means dethatch just as, or just before, growth begins. In cool season grasses such as fescue and blue grass, that is in early spring and early fall. Warm season grasses should be dethatched in the late spring or summer. Do not dethatch now. Consult your local Cooperative Extension Service office for information regarding timing for your county.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!