In this period of high heat, we need to take special care of ourselves and our plants. Just as it makes sense to drink more water in the heat, it makes sense to water plants more often than usual. We water twice as much in July as we do in other months. BUT REMEMBER that plant roots need air, too. And if the soil is continually wet, plant roots won’t be able to use the water, and may rot. The best approach is still to water deeply, but not too frequently.
The best time to water is in the early morning when less water will evaporate, and water droplets can dry from plant leaves early in the day, certainly before evening when fungal diseases can take hold on wet foliage. What does that mean, “water deeply”? It means that when you irrigate by hand or sprinkler or drip, the soil should be moist to a depth of at least 4”. Moisture meters and the old ‘screwdriver test’ are not as accurate as digging a small hole 4 to 6” deep and feeling the soil. If it is dry at 4” just after watering, you will need to water longer.
If vegetation doesn’t completely cover the soil, protecting it from evaporation in the sun and wind, you can use mulch to keep moisture in. To be effective, the mulch should be at least 2” deep (1″ between groundcover plants). We carry two organic mulches, Fine Wood Chips, and Soil Pep, both of which are attractive, stay in place, and will ultimately feed the soil. For mulching rock gardens and very dry native gardens, we also carry squeegee, a fine gravel smaller than pea gravel, which will keep the plants safe from crown-rot while helping to hold moisture in the soil. It is easy to weed through squeegee.
See our discussion of Protecting New Plantings in Hot Weather for ideas on how to help small, recent, and new plantings and transplanting’s survive until the heat is turned down.
And for more information on Colorado heat waves and how to stay safe, click here.