Perennial Plant Watering Guide for Colorado (with our 40+ yrs. of experience)
WATERING IS CRUCIAL TO EVERY PLANTS OVERALL HEALTH AND SURVIVAL
"Water need" will depend on many factors.
Amending the soil and watering properly are the two most crucial steps for a plants survival. We water everything in our nursery almost every day, yes, every day! There of course are exceptions, cacti and succulents can go longer as can some very large potted trees that we carry.
So it rained! Yay, sorry this doesn't give you a pass not to water your trees. Rain water has a hard time reaching the soil directly where the root ball of your plant is, rain tends to get stuck in the upper canopy of the plant and little makes it deep enough to saturate the root ball. We see more plants die right after a rain because people weren't watering & they forget to turn their irrigation back on.
Irrigation capabilities at the planting site should be considered before selecting trees for a planting site. Irrigation not only impacts species selection, but maximum recommended size of the nursery stock and the tree production method best suited for the site.
With infrequent irrigation, most plants will grow poorly, die back or be killed from lack of water because they take much longer to establish. This can happen in 24-48 hours with some plants. If the plant was thriving at our store and died at your house a day or two later...chances are its because you missed a crucial watering. If plants will be irrigated regularly only until they are established (1-2 years), drought tolerant plants should be chosen, and nursery stock of any size can be planted. If plants receive irrigation during establishment and then regularly during the life of the plant, or if you are planting in the plant's native range and soil type, any plant regardless of drought tolerance can be planted.
Irrigation is imperative to a plants overall health and survival.
Regular irrigation after planting encourages rapid root growth that is essential for plant establishment. Irrigation helps maintain and encourage the desirable dominant leader in the plant canopy on large maturing trees. Instead of a dominant leader, trees that are under irrigated during the establishment period often develop undesirable, low, co-dominant stems and double leaders that can split from the tree later.
Splits (so called from frost cracks or sunscald) along the lower trunk have also been associated with under irrigation after planting. Since most root growth occurs in the summer months, irrigation during this time is crucial. You could lose almost an entire year's root growth if you under-irrigate the first summer.
Following the initial few months of frequent irrigation, provide weekly irrigation until plants are fully established. At each irrigation, apply 1 to 2 gallons of water per inch trunk diameter (e.g. 2 to 6 gallons for a 2-inch tree) over the root ball only. We have found that more can be wasteful and that may not be necessary to apply irrigation to the soil around the root ball unless it was exceptionally dry.
Once the plant is established you can water twice per month in warm weather in spring, summer, and fall and once or twice per month in winter in the first three to five years. Between years five and seven, water once every three weeks in warm weather and once every six weeks in winter. After this, most trees should be able to survive on natural rainfall. However, keep an eye on your investment.
Keep in mind watering provides little to zero nutrients for your tree or shrub. Once the ground is depleted of nutrients, your tree or shrub will be starving, which can cause die back, yellowing of foliage, or slow growth. We recommend fertilizing your trees shrub, and perennials at least twice a year, in Early Spring and again in Mid Summer. Without proper fertilization you can not expect proper performance from your plants.
Wilting leaves mean one of two things:
1: The plant is severely under watered resulting in the first stages of visible dehydration.
2: The plant is severely over watered resulting in the first stages of visible engorgement.
So how do you know if you are over watering or under watering? There is one tool you have on you at all times and it's totally FREE! Your hands! The ONLY way to tell if the plant is too wet or too dry is by physically touching the dirt at least a few inches deep into the ground to feel for moisture. You will immediately be able to tell if you should allow the plant to dry out for a few days, or if you need to run to turn the hose.
One of the biggest issues we come across is people using sod irrigation techniques to water trees and shrubs. This is NEVER a good idea! The tree does not get nearly the direct deep watering that it needs to the root ball as much as once a day during the Spring and Summer months. If the foliage or bark is kept damp throughout the day and into the night, fungus, rot, and burning foliage WILL occur. The water droplets creates 1,000's of magnifying glasses all over the plant resulting in 1,000's of burns. It is a complete myth that you can "cool down" a tree or shrub by watering their leaves.
Keep in mind this is true for ALL plants except grasses and greens i.e. lettuce, kale etc.