Watering is one of the toughest topics to cover. Mowing has some hard fast rules that need to be followed. On the other hand, you can hardly print rules for watering because the weather related circumstances are changing all the time. Not only that, but each person has a slight different soil type, elevation or lack of, and exposure to the sun. In addition, there are thousands of different types of plants needing different amounts of water and we are trying to generalize rules. But I’m going to try anyway. Automatic irrigation systems are important when it comes to properly watering lawns. Watering shrubs is probably easier than watering lawns. When shrubs are new they need the most attention. It takes shrubs several years to get rooted in well, so you do have to pay attention to them for a while. As the seasons change your watering habits on your shrubs will change. Irrigation systems are okay if they are installed properly, but initially, I think you should water by hand.
If it is summer you may need to water two to three times a week. In cooler seasons you may be able to water only once a week. We even have dry spells in the winter and your new plants or new lawn will need watered. Do you know how in the winter you skin dries out? Well so do plants. Those cold drying winds desiccate the plant. It would be good to water once a week in the winter if we are not having sufficient rain fall.
What is sufficient rainfall? That’s a tough one. A rainfall of an inch that does a great job of watering the lawn probably won’t be enough to penetrate a good think layer of bark. The best way to find out is the “hands and knees method.” You get out in your shrub bed on your hands and knees and scrape the bark back from around the plant. Then you take a probe like a coat hanger wire and stick it down the side of the hole next to the plant. It’s like checking your oil. When you pull the probe back out if the soil is muddy, there is too much water. If it is powdery dry you better water. What you would like to see on the probe is just some nice even moisture. A thin bamboo stick works well also. How you water is as important as how often you water. Watering by hand is best. That way you know that you are applying the right amount of water to each plant. I like to put a shower/soaker attachment on the end of my hose. Then I count seconds. I like to count maybe 45 to 60 seconds for smaller plants and twice that for larger plants. But I split it into two soakings. I water all the shrubs in the bed once counting out about half my time and then I water the shrubs a second time with the remaining seconds. I find trying to put all the water on at once may result in the water running off instead of soaking in.
You can water shrubs any time of the day or night but when it comes to watering lawns you should avoid late afternoon or evening watering. If you water too late in the day or in the evening, the grass blades will stay wet all night long and eventually cause a fungus. New lawns should be watered frequently but for short time periods. Something like watering two to three times a day for 20 minutes might work. The goal is to simply keep the sod wet and the soil directly under to sod.
There is no reason for long soakings on new sod since the root system is not developed yet. As the new sod starts to take root, you will water less frequently but for longer durations. Some general guide lines for new sod might be the first week 3 times a day, the second week two times a day and by the third week once a day. Each time you are increasing the amount of time you water. Of course, this will vary greatly on the time of the year and the temperature. Be very careful with new sod laid during the hot dry summer months that you do not allow it to dry out. A simple tug test will tell you how well your new sod is rooting. After a week or two grab the grass firmly with two hands and gently pull. Hopefully you will feel some resistance. This means the sod has started to root in. However, to get the sod thoroughly rooted in takes much longer. New sod could take 6 months to a year to be thoroughly rooted depending on the time of year and how much sun the sod receives. The shadier the location the longer it takes to root. After the new sod is rooted in the watering habits change. Your goal now is to water one inch to two inches per week. During the cooler months you can water one inch per week and water two inches per week when we are really hot and dry.
DO NOT water your lawn every day, this is very detrimental. You should apply one inch in one day for the week or again if we are really hot and dry you should apply two inches, one inch on two different days per week. So as not to confuse anyone you are applying one inch with each watering, either once or twice a week. Automatic irrigation systems are the best thing since sliced bread. It becomes important in our area because of the rolling hills. A lot of you may experience run off when applying one inch of water. That is when you use the soak and wait method. You let your irrigation run for 15 minutes in a zone and then wait at least 15 minutes for that to soak in before watering that same area for another 15 minutes. Keep repeating 15 minutes in each zone until you get your one inch of water. For those of us with level or close to level lawns, I can run each zone just once and apply my one inch without any run off. Mature shrubs rarely need watering and should not run on the same cycle as does your lawn. How do you know when you have one inch? The best method I know is to set out straight edged cans to catch the water and then measure the amount of water in the cans. The cans HAVE TO BE straight edged, no slanted sides. All straight edged cans little or big will catch water at the same rate. I like to set out about 12 cans in one zone and then let that zone water for about an hour. I then go and check each can. You will be surprised at the different amounts of water per can. You use an average per can to determine how long it will take your system to get an inch. Photos