DEAR JOAN: We have some animal tunneling around our raised bed gardens. Almost every day, I need to smash down a new tunnel path, only to find a new one the next day.
It is surprising to me, because the soil around these bed is so hard and rocky.
I am afraid they will eat the flowers and vegetables in the beds, not to mention uplifting the ground with their tunnels.
What do you think they are, and how do I get rid of them?
Jon S., Morgan Hill
DEAR JON: There are a couple of ways to identify your mystery tunneller.
Look for mounds in your yard. A mole hill will be close to perfectly round, looking a lot like a miniature volcano with an opening, usually plugged, in the exact center. A gopher mound is crescent or horseshoe shaped, and the entrance plug will be off-center.
The tunnels also can be revealing. Moles burrow living chambers about 2 feet below the surface. They also tend to excavate a lot of tunnels that spread out like a matrix in your yard, pushing the dirt out to make many hills.
Gophers’ living chambers tend to be about 6 feet underground with connecting tunnels that rarely show up on the surface.
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Other than creating a messy looking yard, moles are fairly harmless. They eat insects — mostly grubs and worms — in the soil. Gophers are the ones that eat your plants. The only times moles harm plants is when their tunneling loosens the soil around a plant’s roots.
Gophers can damage a garden pretty quickly, eating the roots of a plant as well as pulling the entire plant underground. In the spring, they often emerge above ground to munch on tender growth.
Both animals are territorial, so chances are good that whichever one you have — I suspect a mole — you likely just have one. The bad news is, of course, that even one can be too many.
If it’s a mole, I’d suggest letting it be. Stomping down the tunnels is a good way of dealing with it, and it might get so tired of having to redig, it will move elsewhere.
Moles are much more difficult to trap than gophers, but you can discourage them by getting rid of grubs in your lawn through the use of beneficial nematodes and avoiding overwatering the grass. Castor oil repellents and growing daffodils, marigolds, alliums or fritillarias also may work.
Gophers are rodents that just keep, er, giving. There is no sure way of getting them to move on, which means the most effective way of dealing with them is through lethal trapping. However, even if you manage to kill the gopher, another one is likely to move into the vacated tunnels. Yellowjackets also like to use the tunnels for their nests.
You can protect your plants by placing hardware cloth at the bottom of your raised beds, which would have been better news if I’d told you that before you filled them with soil and planted in them. Creating underground fencing also is effective.
Gophers purportedly dislike certain smells, so you can try growing rosemary, sage, thyme, eucalyptus, geranium, pine and lavender, or use coffee grounds, peppermint oil or castor oil as a repellent.
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