How and When to Water Your Plants?

Recent studies have confirmed that water on the leafs of plants can cause sun damage, as the water droplets focus the light rays, causing burns (see here). Thus, you should avoid spray watering your plants, especially here in the Arizona desert, which has intense sunshine due to the low humidity.

Hands down, flood irrigation is the best watering technique for the desert. Build an earth wall berm around the outside of your growing area, then just flood it with water. Be careful not to overflow the berm wall, as a little leak over the edge will quickly erode a huge hole in the wall.

For the most efficient use of water, irrigate in the evenings, to avoid excess evaporation.

You can do day-time flood irrigation during the heat of the summer to cool off the ground. I have kept tomatos going all summer long, in full Arizona sun, by heavy flooding and intentsive plant spacing. The intensive spacing creates a shaded zone under the plants, which along with the water, helps the plants survive the brutal heat.

The Secret to Arizona Gardening: High Berms

Berms and deep watering.

I just raised up and strengthened my berms this week, to help the plants cope with the extra heat. Small berms are ok for the mild spring months, when just a light soaking will keep the soil moist. But for the 90+ degree days of late spring/early summer, a deeper soaking is necessary.

With only shallow watering, the plant roots only grow shallowly, because the water never really penetrates the soil more than an inch or so. With deep watering, the soil will get moist deep down, and the roots will follow. Those deep roots will keep your plants much healthier when the real hot days hit.

So in order to get those deep waterings, you have to let the water pile up and sit for awhile, and slowly set down in where you want it to go. I recommend berm edges at least 4 inches high all around your growing area. That way you can flood your growing area with 2-3 inches of water at a time, and the water stays right where you want it.

Just be careful to watch that the water doesn't rise above the berm edge. Once the water flows over the edge, it will quickly rip a huge hole in your berm wall and all the water will escape.