Wow, what a dramatic title you may be saying. Well, the truth is that in my 20+ years of experience in the green industry I can honestly say that the most common mistakes people make in caring for their lawns and landscapes are due to improper watering and mowing/pruning. Today, let's cover watering.
I say improper because many people think that the only watering problem is that they do not water enough. In truth, I see far more problems from over-watering than I do from under-watering. The issues with not watering are drought stress and in extreme conditions plants that are susceptible may not survive. This really depends on the plant and you need to take inventory of your lawn and landscape to know which plants are more susceptible than others. I will begin a list of plants that in my experience will not survive the summer without irrigation on another page.
Now once you have determined which plants are susceptible you can begin to determine what portions of your yard must be irrigated just to survive. However, as I mentioned above, I see far more problems from over-watering than from under-watering. In fact, some issues that may appear to be from too little water in the summer may have been caused by too much water in the spring. Confusing huh? Well hang in there and become a watering expert!
Problems from over-watering are primarily disease issues. In lawns, the most common problems we see are Grey Leaf Spot Disease and Brown Patch (Large Patch) Disease. In our landscapes and this is far more common than any other problem with plants that I see, it is Root Rot. Let's start with the lawn.
For most of the year in our area irrigation of the lawn is not needed. That's right you don't need to water at all. From November till May the temperatures are moderate and we usually receive adequate rainfall to keep our lawns in good shape. So that leaves us May through October when our lawns need extra irrigation. If we are getting regular rain you may not even need to water the lawn during this time either but it is not likely that we will go through a summer in this area and not experience a few weeks of drought. So how much is enough? The answer depends. It really takes some thought to get it correct. So, let’s start with the basics, if you know nothing else the rule of thumb is 1" of irrigation per week, and in extreme heat and drought increase that to 2-3 times per week. To determine how long the sprinkler needs to run to get 1" of water set an empty tuna can on the lawn and time how long it takes to fill it. So why would you need to know anything else? Here are the other factors that determine how much irrigation your lawn needs. Soil type (sandy, loam, clay). In our area, we tend to either have clay soils or sandy soils. Some lawns have both, especially areas of new construction where the lots were built up using river sand. The lawn can be sandy around the house and clay where no sand was added.
The next factor would be how much sunlight each area of the lawn receives. Sunny portions of the lawn need more irrigation than shady areas. In fact, some shady areas can survive without much water at all. Consequently, shaded areas are also where we frequently see disease problems due to excessive moisture and higher humidity.
For the landscape, once you have determined which plants need more irrigation than others (sometimes those that do and those that don't are right next to each other) the next step would be to examine the depth that your plants are planted. THE most common problem with landscape plants that I see are plants that are planted too deep in the soil and thus suffocating. For any plants that are planted where the crown of the plant (the point where the plant begins to branch out from the trunk) extreme care needs to be taken when watering and in the late fall to early winter these plants should be dug up and then re-planted at the proper depth. Also, take notice of low-lying areas of the landscape beds. If water is settling in the bed around a plant it is going to have problems and should be corrected. Now that all of your plants are at the proper depth determine your soil type. Not only should you examine the soil around the plant but if possible, see if you can determine what the soil is like well below the plant where the roots will be growing. As we said before clay is very common in our area. Even when there is a good landscape mixture in the bedding areas often there is clay below. If you have ever taken some of this clay and set it out in the sun you can tell that it hardens and will hold water. So, if there is clay below the surface it is just like planting in clay pots. Excessive watering will be held in the soil and suffocate the root system, and as plants grow if they cannot push roots through the clay, they may outgrow their root structure's ability to sustain their size. This is why a large plant that has been planted often for a very long time will suddenly start to decline.
How to determine if your plant has root rot! The first sign of root rot tends to be a portion but not all of the plant seemingly overnight dying. Usually, this is a stem or an entire branch or trunk of the plant. Often this problem began in the Spring but will not show up until the hot dry months of the Summer. This is because until the conditions became difficult the plant was able to survive on the root structure that is still in tack. When the right conditions arrive, the plant trying to survive stops sending water and nutrients to portions of the plant. The plant is trying to survive!
OK so now you see why this is not as easy as it seems at face value. Here are the other guidelines for watering: When to water; preferable in the early morning hours. Why? The idea is to wet the root system not the leaves and branches of the plant. Watering in the morning allows the plant to dry out over the course of the day. Plants that stay wet overnight develop disease and insect problems. Whenever possible I prefer to water landscape plants with a "soaker" hose. This waters only the root system and not the entire plant. Watering in the middle of the day over the top of the plant can cause scorch. Droplets of water act like a magnifying glass causing sunlight to scorch the leaves or tips of the leaves where water collects.
OK, now you are a watering expert! You are now free to move about the lawn! For more information speak with your lawn or landscape technician or schedule an appointment to meet with your technician.