Three things all plants need to grow are the sun, water, and carbon dioxide. Different plants have different requirements for sun and water, so knowing if you are watering correctly can be tricky–particularly when referring to your lawn. Grass has different watering needs than other types of plants. Different varieties of grass have different watering needs from other varieties. There is not a one-size-fits-all approach to watering, though there are a few general guidelines to help determine if you are watering properly and if you need to make adjustments.
The way plants respond to dehydration has been extensively researched. Recent research seems to indicate that plants have “stress memory,” which is indicative of how a plant will react to future subsequent exposures to dehydration. We will get more in detail with that later on in this article. In order to determine if your lawn and garden is getting the water it needs, it is important to understand a little bit of the science behind it, and the crucial role water plays in photosynthesis.
Photosynthesis is the process in which plants convert energy from sunlight to produce glucose from carbon dioxide and water. This conversion is associated with the action of chlorophyll, which is the pigment in plants that makes them green. Water is involved in the early stages of photosynthesis, and the absence of the water molecule can ultimately result in plant death. During photosynthesis, the chlorophyll molecule becomes oxidized, which means it loses an electron and gains a positive charge. This oxidation results in the splitting of the water molecule into separate molecules, H2 (molecular hydrogen) and oxygen, and the transfer of light energy to ATP (adenosine triphosphate) and NADP (nicotinamide adenine dinucleotide phosphate).
Lawn and Plant Hydration
Since water is a crucial part of photosynthesis, it is easy to understand why proper hydration is so incredibly important. Unfortunately, most homeowners rarely find the perfect balance of watering. The result is either wasted water and potential for disease, and shallow roots in the case of overwatering, and thin, weedy, dying grass in the case of not enough hydration. To determine your lawn watering needs, set three or more flat bottom cans or bugs throughout your lawn. Make sure they are at least four feet from the source of irrigation and turn on your sprinklers for fifteen minutes. After fifteen minutes, measure the depth of water inside each container and then average the depth. Typically, the lower the depth average in your containers, the longer you will need to water each day. For every inch of water (as averaged by containers), you should water for 15 minutes per watering day. The number of times per week you will water will vary on location, soil conditions, and weather conditions.
Know When to Water
Believe it or not, most lawns only need watering once every four to eight days to stay healthy and green. Seem like it’s not enough? The truth is, watering deeply but less frequently encourages deeper and longer roots in plants. Why are deeper, longer roots important? Longer roots will generally have more root hairs reaching into the soil. These root hairs are essential for absorbing water and nutrients for the plant’s use during photosynthesis. Deeper roots create a hardier plant that is more resistant to drought, disease, and weeds.
There are two primary visual indicators that will alert you to grass in need of watering. They are visible footprints and a bluish-gray tint. If you see lingering footprints in your turf thirty minutes or more after having walked through the grass, it is likely in need of a drink. When the grass turns a bluish color when exposed to direct sunlight, it also needs water.
It is important to note that it takes less water to maintain a healthy lawn if soil fertility is high. A well-fertilized lawn also helps to keep down weed levels. Many homeowners will fertilize once or twice a year. While this is undoubtedly better for your plants and grass than not fertilizing at all, it is ultimately better for your greenery to split applications up over the course of the growing season–ideally into four applications. These split applications reduce the potential to burn your lawn and the risk of surface runoff and deep leaching from too much nitrogen. A good fertilizing schedule is to apply nutrients during each holiday during the growing season: Memorial Day (end of May), Independence Day (July 4), Labor Day (end of August), and Halloween (end of October). Notice the fertilizer applications are made closer together at the beginning of the growing season (roughly one month apart). This is because grass is most actively growing early in the season and requires the highest concentration of nutrition to thrive.
Water Deeply and Less Frequently
As already mentioned, watering less frequently but deeply into the ground does wonder for creating healthy turf and plants. This deep and infrequent watering creates turf that is more resilient to drought stress. The amount you water per session should equal about one inch of water. This translates to around six inches of soil moisture. This is all your turf needs per week to remain healthy and happy. Watering more frequently can result in shallow roots, which are then more susceptible to pest invasions such as weeds, moles, beetles, grubs, and fungal infections.
Water in the Mornings
The ideal time to water is early morning. Watering between the hours 4 a.m. and 9 a.m. is generally best for turf, plants, and shrubs. Note, you do not want to water for the entire five-hour window–watering for the determined amount of time to achieve one inch of water (or six inches of soil moisture) is sufficient for the needs of most of your greenery.
Why water early in the morning? There are a few reasons why watering early in the day is better for your plants than late in the day. First of all, watering early allows for extra surface moisture to evaporate off during the day. Watering in the evenings allows moisture to remain on the surface for too many consecutive hours, which can lead to a variety of diseases and infestations. Morning watering allows soil saturation, but any surface moisture will be able to evaporate during the day.
Ideally, your grass should only be watered one to two times per week. However, hotter and drier climates may require watering as much as three times per week. Certain types of turf may need to be watered more or less frequently, so it is crucial to understand the requirements of the particular kind of grass your lawn has.
Irrigation systems can make watering fairly effortless and require little oversight once set up. However, automatic sprinkler systems can present some additional challenges that other types of irrigation do not. Because sprinkler heads are designed for a certain amount of overlapping to provide sufficient coverage, certain areas of your turf may be susceptible to over-irrigating. Head-to-head spacing is most common as it allows the most uniform coverage. Heads are spaced at half of the sprinkler range diameter. An even better tool to have at your disposal is a rainwater or soil moisture sensor. These will override your sprinkler system and turns them off when a designated amount of water has been detected. These sensors can be invaluable to achieve the optimal amount of moisture for healthy turf.
As already mentioned, the optimal amount of moisture needed in topsoil for healthy grass growth is around six inches. Any more, and you could potentially have diseased grass or pest infestations. Regardless of whether you are getting the recommended six inches of water per week, or you happen to experience large amounts of moisture, proper drainage is imperative to ensure your turf remains healthy.
Proper drainage begins with proper soil structure. Loamy soil is the goal, which is the right balance of sand, silt, and clay. However, even loam soil can become compacted over time, leading to poor drainage. Aerating soil regularly can help promote proper drainage in your turf. If you do not have a good, healthy soil to begin with–i.e., soil which is too sandy or too clay, you can correct these as well to help promote proper drainage. For sandy soil, adding compost or manure and tilling it in will help retain moisture. For clay soil, adding peat, sawdust, bark, compost, or manure and working it into the soil can help improve the quality. The thick, compact consistency of clay not only makes it difficult to establish roots, but it also retains too much water.
Grading is another important component to providing adequate drainage for lawns. Ideally, lawns should be graded at a 1-2% slope. This allows water to run down to a low point such as a drainage ditch, catch basin, or dry well. Surface grading is often the best solution for poor drainage, though it is disruptive to the existing landscape. If your lawn has low spots or areas of poor drainage without any outlet for runoff, break up the existing compacted soil with a tiller or backhoe. Fill the area with soil that is the same texture as existing soil.
It is difficult to set specific parameters for watering plants, as they may differ tremendously from one plant to the next. However, some general guidelines include:
1) Keep soil evenly moist. Water evenly and keep the soil damp. Slight drying out between watering is acceptable, but avoid drying out completely. Ideally, you should water plants very thoroughly, but less frequently. Like grass, most plants and flowers only need a deep soaking once or twice a week.
2) Water in the morning! You want to water your lawn for 20 minutes in the morning just as the sun is coming out. Watering at night promotes fungal diseases on lawns.
3) Water gradually. When you add water to the soil, it takes a while for it to soak into the ground. Watering too quickly can result in much of the water running off the surface without allowing it to soak in. Watering more slowly gives the soil adequate time to soak it up before adding more water to the plant.
Dehydration in plants occurs in multiple stages. In the early stages, plants begin to wither and wilt. Lack of water causes the slow growth of plant cells and reproductive failure. It arrests photosynthesis, which is critical to plant survival. Water stress affects different plants in different ways. Most plants, however, can adapt themselves somewhat to drought conditions. Their strategies to cope with dehydration involves a combination of stress avoidance and tolerance mechanisms. The way a plant responds to dehydration depends largely on its response in the early stages and can help it survive for some time. Dehydration avoidance involves the plant’s ability to retain water within its tissues enabling it to go longer without water. Succulents are examples of plants that are conditioned toward drought avoidance by retaining water within the tissues of the plant. Tolerance mechanisms enable a plant to withstand dryer conditions than it is accustomed. This includes developing an extensive root system to reach deeper into the soil for water. In severe cases, water stress is fatal to a plant.
A certain amount of dehydration in plants can be beneficial in that it helps develop longer and stronger roots. In the early stages of drought, plants can bounce right back even stronger and more resilient than before. The combination of avoidance and tolerance mechanisms allow plants and grass to become somewhat resistant to dry conditions without causing any lasting issues.
Watering your lawn and garden is more complicated than simply turning on the sprinkler system. The science behind it is relatively complicated. It requires a delicate balance–too much water makes plants susceptible to disease and infestation. Too little water results in stunted plant growth, arrest reproduction and photosynthesis, and can eventually lead to complete cell death. Proper hydration is one of the most basic needs of your lawn and garden. When armed with the right knowledge and strategy, giving your greenery proper hydration does not have to be complicated. Watering with the correct techniques will provide you with a beautiful, vibrant lawn and garden that is healthy and thriving.