This is the most common question when it comes to figuring out how to effectively take care of your trees and shrubs. For starters, you must know the difference between the frequency you are watering your plants and the quantity of water the plants are getting each time. Days per week mean the "frequency" while the number of minutes means "quantity". It is very important to change the frequency of watering as the seasons changes, but you should try leave the number of minutes the same. Below is a basic example of how often you should water your plants during winter, summer, spring, and fall:
Winter Fall to Spring Summer
Bedding plants and vegetables 1x per week 2x per week 3x per week
Trees 2x per month 1x per week 2x per week
Shrubs 1x per week 2x per week 3x per week
Desert Plants 1x per month 2x per month 1x per week
Now for some general guidelines for watering plants in Las Vegas, Nevada. You must also know that this is a starting point for healthy plants and when sunlight, soil, and plant type vary greatly, so will the water requirements. Las Vegas and Henderson landscapes are mostly very slow to drain because they are made of clay, sand, or loam. Know the characteristic of your soil, and specifically where you intend to plant if you are doing this without the help of a professional. For instance, if the plant is on a slope then it may drain quite a bit faster. So, how much is too much water? For living in the desert, this answer will also vary depending on the weather. Here is a list of the typical amounts in this area:
Winter Fall to Spring Summer
Bedding plants and vegetables 30 minutes 30 minutes 45 minutes
Trees 2 hours 2 hours 2 hours
Shrubs 1 hour 1 hour 1 hour
Desert Plants 1 hour 1 hour 1 hour
Bedding plants and vegetables are often water the same as the lawn since they tend to be in the same zone. If you see this method working for your plants, by all means stick with it. If the drainage isn't that good then I suggest another method. Poor drainage means soggy soil causing root rot. Overhead sprays from the lawn sprinkler can cause misshapen fruit, blossom, stem rot, leaf spot, and other fungus problems especially in the hot desert weather.
Blossom rot Stem rot Leaf rot
Shrubs and trees have a deeper, more extensive root system and different water requirements.If possible, you should have them on s different valve or time zone in your irrigation system. A good rule of thumb is 1-2 gallons of water for smaller accent plants, 3-5 gallons for larger shrubs, and 10 gallons of water are needed for a 15 gallon plant every time you water .
Desert plants will always need thorough, widely spaced watering to look their absolute best. Once established, watering only once a week, and even less in the winter will work well for almost all desert trees and shrubs. Cacti needs water even less often. A good soak every 2 weeks should be sufficient.
As you are aware, watering in our desert climate is not an exact science, and it isn't as simple as it may seem. Just remember, please choose the right irrigation system for your landscape and learn how to run it the proper way, or you can consult a landscape professional.