Importance of Surface Mulch for Vegetables

Surface mulches are under appreciated when growing shallow rooted vegetables during the heat in hot, desert or arid climates. Learn why.
Using mulches when growing vegetables can be very important in hot, dry climates. Garden soils dry quickly and a surface layer of mulch helps keep the soil cooler and retains soil moisture much better than a loose, uncovered garden soil. This can be particularly beneficial to shallow rooted vegetables such as onion, garlic and other root crops. 

Try to use light colored mulches like this bedding in the summer months to help reflect energy from the sun and keep it from heating up the soil. In the winter time when the air temperatures are much cooler, use dark colored mulches to help warm the soil and speed germination. Mulches help keep the soil cooler, retain moisture and suppress weed seed germination. Organic mulches which decompose help add structure to desert soils. 

The problem has been what to use and cost. In the past I have used clean, bailed straw but it is expensive and doesn't decompose rapidly when it is fresh. You can turn it under after harvest and it will decompose but it decomposes rather slowly.

I tried using wood shavings like you can use for horse bedding. It works well as you can see from this picture of onions that were mulched versus onions that were not mulched in front of them. The horse bedding can be turned under easily after harvest and decomposes rapidly in moist soils. I was pretty impressed with it and it's cheap. I got the horse bedding in 3 1/2 cubic foot bags from Viragrow in Las Vegas for $4. I am sure you can find it other places as well.

I put down about half an inch of horse bedding on top of the soil in April before the heat and it made a big difference. If you are going to seed in the heat, I would highly recommend mulching the surface with something like this. You can also take the time to shred newspaper and it will do about the same thing. A big problem starting plants from seed in the garden during the heat is the soil drying too quickly and the see failing to germinate or germinating very slowly.