Shrub and Tree watering

Asked May 28, 2013, 12:32 PM EDT

We have 20 5 gallon shrubs planted two years ago watered via a single drip irrigation system. In general, how much water should they be getting? I will add/delete emitters as appropriate since the drip line is all in one zone. The holly shrubs seem to be having the most difficulty thriving. The other shrubs are: Lilac Burkwood, Systena Plum, Spirea, and Kelsey Dogwood. I can adjust the emitters individually as needed.

We also have a two year old Newport Plum tree approximately 3 diameter inches at a height of 3 feet.. How much water should it be getting weekly

It is advisable to water these plants weekly or bi-weekly?

I live in Littleton with clay-like soil but included mulch when they were planted

Thank you very much.

Arapahoe County Colorado trees and shrubs

3 Responses

Holly bushes can be challenging in Colorado. Here is a Planttalk article about hollies.

Congratulations on using drip irrigation! It is a great watering method, especially during drought.
Drip irrigation systems are generally designed to operate for one hour of run time per week after plant establishment.
The general rule for shrubs:
A 1 to 5 foot shrub and small tree less than 15 feet at maturity will initially require two, 1 gph emitters 12 inches from the base of the plant. A 5 foot or larger shrub may require three 1gph emitters.
For your plum tree (larger than 15 feet at maturity):
For now use 2 - 4 gph flow emitters 2 feet from the trunk. As your small tree grows, increase to 4 emitters.
The fact sheet, "Drip Irrigation for Home Gardens", is a great resource.

Thanks for the information regarding emitter selection. With those emitter's how many gallons per week or per watering should the plants be getting? Is it better to water plants all at one time once a week; or spread the gallon's per week over several days during the week.

A shrub the size of a plant growing in a 5 gallon nursery container should receive 4 to 6 gallons weekly. Large shrubs may require 10 to 12 gallons of water weekly. The dryness of the soil around your shrubs will determine whether you should water once a week or twice a week. Check the soil moisture at the rooting depth of the plant the day following running the drip system. Adjust irrigation run times accordingly, that is, if it is bone dry, they need more water coming out of the emitters (or they are clogged); if it is soggy, you need to decrease the water; if it is moist you have it set correctly.

Using a drip system employs the same principles as irrigation that sprays into the air. The idea is to deliver water to the plant roots and keep the plant hydrated to the capacity the plant needs. If it rains, you don't need to water (or water less). If the days are long and the air temperature is near 100 degrees, the plants need more water. As the days shorten and temperatures are more comfortable, the plants will need less water.

I hope this information helps.