Watering During the Dog Days

By Indigo Deany  |  Fort Collins Nursery

Welcome August – welcome heat waves, fiery air, crispy edges, languid and listless stirrings. This is the solar season, where the smoldering sun bests even the most committed and enthusiastic gardeners. One of the many lessons of gardening is to listen to what the world around us is saying, even when it’s hissing at us to stay inside, human, your roots are not deep enough to withstand this heat. Plants, on the other hand, have the advantage. With their roots able to reach deep into the cool, dark earth, they are able to weather this midsummer heat, as long as we give them support. In Colorado, we all know that water is precious, scarce, and expensive. So how do we get the most from it while keeping our gardens alive in this dry, summer heat?

There are multiple methods of using water efficiently in your garden that are, these days, conventional wisdom. They bear repeating because they work: mulch your beds, use a drip system if you can, water during the early morning or evening, and collect water in a rain barrel. However, one of the most consistently misunderstood and perhaps most important methods for efficient water use and plant health is simply to water plants deeply. It is always, almost without exception, better to water somewhat less frequently and more deeply than to give your plants a small amount of water, say, every day. While there is no easy way to define “deep watering” because plant species, site conditions, season, and water delivery method are all factors that affect the watering calculus, understanding the principle of deep versus shallow watering is essential. 

In short, roots will grow where the water goes. Watering the top two to five inches of soil – even if done every day – causes the roots of plants to hover around that small halo of moisture. This can have devastating results as soon as a watering is missed or there is a particularly scorching day. The water in topsoil evaporates quickly, leaving plants without access to moisture. In our gardens, this is often remedied by a second emergency watering, leading to the use of more water for less payoff. On the other hand, if a plant has developed its root system to its maximum depth, it has access to water stored deeper in the soil that won’t evaporate between waterings. There are other crucial benefits to the maximized root system, too: plants will have access to a broader supply of nutrients stored in the soil, and the diversity of root systems of different plants leads to less competition for both water and nutrients. This leads to resilient coexistence, not only between plant species but between us, our plants, our water bills, and our water ecologies.

When you’re next watering, visualize the water soaking into the soil at a depth past the root mass of your plant; this will encourage the roots to grow deep and strong. It’s okay if you don’t know exactly how deep roots are, guessing is good enough! In the long term, you will save water by watering deeply and less frequently, and your plants will be significantly healthier and more resilient, to boot.