Well, summer has arrived and so have the drought restrictions, a regular part of living in Southern California!
Our local water municipalities are good at reminding us to water on certain days of the week. But we at Root & Branch wanted to give you some information and tips to make sure your landscape makes it through the season.
Not to get to science-y, but when a water agency tells you to water early or later in the day, it’s because of evapotranspiration which, in a nutshell, is the rate of which a plant and the soil lose moisture through evaporation. The factors that affect the rate of evaporation are solar radiation, temperature, humidity and wind.
Studies by the Universities of California Davis and Riverside all conclude that watering early in the day is better than watering your gardens in the afternoon. And by early in the day, we mean between 4 AM and 6 AM, when there’s less wind, soil temperatures are cool, and plants’ roots are most able to absorb water.
You might also have heard it is better to water less often but for longer periods of time. Turns out, there’s really good science behind that too. A plant’s root system typically reflects what we see of the plant above ground. Meaning short plants have shallow roots (think grass) and tall trees have large, deep roots.
So if you are watering for a short period of time you’re only getting water just below the surface. This provides water to roots within the top few inches of soil, which isn’t how most plants grow. Watering for a longer period of time will allow the water to get to the roots at greater depths.
This provides water to the plant, of course, but also encourages the roots to grow deeper into the soil. This then acts as an insulator to the root system in high temperatures.
Grass is a terrific example of this! It should be kept longer in the summer – 2 to 3 inches is good, 4 inches even better. Not only does it shade the ground from the increased blade height, but it also encourages the roots to grow deeper. Also, again, a longer run time less often will encourage those roots to go deep, insulating them from the heat while the blade is insulating them from above. So, tell your gardeners to change the height of the darn mower!
If possible, consider upgrading your irrigation controller to a “smart” one. Controllers now have moisture sensors and some can now connect to a local weather station and automatically make watering changes based on environmental conditions. As we mentioned, the water needs of plants are affected by sun, temperature, humidity and wind. These smart controllers do calculations that take into account all these factors, as well as the type of plants they are watering, to make sure you provide the exact amount of water needed, and not a drop more!
If that’s not in the budget, consider at least using a water meter. Actually, if you have a garden you should have a water meter. This is the time of year when they are worth their weight in gold. See our blog post about water meters for more information on that topic.
Hopefully you and your garden can beat the heat this summer. A few adjustments – and maybe some tools – are all you need to make it happen for your plants. As always, feel free to comment below, we really enjoy your insights!