You might have your warm season garden in the ground already, and now you’re wondering how to keep those plants alive through the difficult times ahead. Since the Mojave is the driest desert in North America, our water situation should always be at the top of a gardener’s worries. If you’ve created a vegetable garden, then you know how essential it is that those plants are neither soaked nor dried out. To keep tomatoes, cucumbers, and any other fruiting vegetable from developing blossom end rot, cracks or other disorders, it’s critical to keep them evenly moist. Think of a really well wrung-out sponge – you don’t want your soil to be much wetter or drier than that.
Too many gardening problems in Southern Nevada are the result of improper watering. Too much – the plant drowns and dies. Too little, the plant dries and dies. No doubt, you’ve established your watering system. I trust it’s more than just a hose. Maybe you’ve expanded your irrigation to keep your raised beds regularly watered.
Yes, Mojave Desert horticulture can be tricky! And this isn’t even talking about our temperatures!
While we can’t solve all garden problems, we can ease them a bit.
The answer is – MULCH.
I say the word mulch, and everyone has their own idea of what I’m talking about. First: you know it’s not the same as compost. Mulch can be pretty much anything that you put on the surface of the soil around plants. A local horticulture star in the valley once told me that if you lie down on the ground, you’re mulch. If you stay there too long, you’re compost.
Aside from that, there’s a whole range of products you can use, depending on what you’re trying to do. First time I ever heard of someone using mulch, back east, home gardeners were putting layers of black plastic over the rows between plants. The point of using that kind of mulch was twofold: first, to cut down on water evaporating from the inter-row space. And because it formed a little dark environment, it cut down on weed seeds that needed light for germination. Unfortunately, all that black plastic turned out to be a big problem. It didn’t degrade, so it took up a lot of space in land fills. And the stuff is pretty fragile, so it’s easy to rip, and that defeats the whole purpose – once there’s a tear, light gets in and moisture out. To block light and inhibit weed infestation, a good idea is dark colored landscape fabric. You can buy it at any garden center around town. It’s definitely more expensive than plastic, but it lasts and can be reused.
A good way of slowing down evaporation is to place a layer of organic mulch on your vegetable garden. Don’t be worried about the term organic. I just mean something that’s been alive in recent memory. Straw, the same stuff they use for horse bedding, can be a very useful mulch. You put it on the vegetable bed, between plants. Pile it up loosely about 3 inches thick without covering the plants you want to grow. Picture a 3” thick thermal blanket. This is dense enough to block light from reaching weed seeds, so that cuts down on annual weeds. It also slows down evaporation from soil, so the plants don’t lose so much water so fast.
There’s another benefit of this kind of mulch –it is like a thermal blanket. It tends to keep the soil from becoming too hot or cold. By modulating the soil temperature, it helps to limit the stress on plants. If you could picture plant roots panting (that’s without mulch), then picture them relaxing in the shade (that’s with mulch), you’ll get a sense of the positive effect of mulching.
If you’re going to use mulch, and I strongly suggest you do, apply the kind that makes the most sense for your purposes. You probably shouldn’t mix mulch types. For instance, don’t use gravel and straw together. Gravel is for desert and desert adapted plants. Landscape cloth with chipped bark works best for perennial, ornamental gardens, and straw for vegetables and other annuals. You can work the straw into the soil at the end of the season, because ultimately it will break down and improve the soil.
Mulch – it’s great stuff.
For KNPR's Desert Bloom, this is Dr. Angela O'Callaghan of the University of Nevada Cooperative Extension. Stay well, my neighbors.