Drought Watering Tips
With the extended drought we have been experiencing, special attention needs to be paid to the landscape. Each type of plant in the landscape requires different types of water and different amounts. And, unless you have your own well, water can be expensive. Often in drought situations there are watering restrictions, limits, and prohibitions, so choices need to be made as to which plants to water and how often.
Below, you will find tips on how to water, what plants to water, and how often to water.
When To Water
Water in the early morning, such as 4am- 9am, to reduce evaporation and decrease the chance of diseases occurring from standing water. Watering in the afternoon or in weather above 90 degrees may cause up to 50% of your water being lost due to evaporation before it even enters the soil.
How Much Water Is Enough?
It is very important to remember that your water pressure may be different from other properties, so the amount of time to water can be inadequate. You should measure how much water you apply in inches of water, not minutes of watering.
The following is a general guideline for how many inches of water per week:
Trees (without plants or lawn under the canopy): 1”-2” Per Week
Trees (with plants or lawn under the canopy): 3” Per Week
Water Loving Trees: 3” Per Week
Shrubs: 1”-2” Per Week
Lawn: 1”-1½” Per Week
Perennials: 1” Per Week
Annuals: ½” Per Day
Increase these weekly totals by 1” when temperatures are over 90 degrees.
How To Water Correctly
The old rule of thumb is to water infrequently and heavy, rather than frequently and light. Most established plants and lawns need between 1” and 3” of water per weeks. This water should be applied in one or two waterings over the week.
One inch of water, depending upon soil type, should saturate from 10”-15” into the soil. Most sprinklers need to run for 60 to 120 minutes to apply the correct amount of water to an area, depending upon water pressure, soil type, and other variables. A slow, saturating soaking at a lower water pressure is much better than a fast, high pressure watering. When watering a hillside, lower the water pressure if you see water run-off occurring.
Avoid shallow, frequent waters of all plants, as this leads to plants developing shallow roots and becoming more susceptible to drought stress. Remember to also ‘water where the roots are’. Water around the outside of the plants, not the leaves themselves. Roots are the part of the plant that absorbs water for the rest of the plant, so provide 100% of your water to the roots, they will take care of the rest.
Cool-season lawns (99% of our area) such as Bluegrass, Ryegrass, or Fescue, normally require 1” of water per week to maintain a growing, green, healthy appearance. However, in a drought, lawns could require as much as 2”-3” of water per week, applied in 1” waterings. The self-protective mode for lawns is called dormancy, where the plant stops growing to conserve water. Lawns can live in this state with minimal water for quite a long period of time. The yellow, straw like appearance indicated that the lawn has entered dormancy. Once this state has occurred, the grass blades and the roots have both stopped growing. However, when cooler temperatures return, such as in September, the lawn will break dormancy and return to a green, growing state.
If you do decide to water your lawn, water faithfully on a schedule. Lawns that are brought in and out of dormancy on a regular basis are more stressed than one in a constant dormant state.
Trees are the long term investment in your landscape and should be your first priority in a drought. Annuals and perennials that are inexpensive and quick growers can be replaced much more easily than an established or mature tree. Woody plants such as trees will not need daily watering in a drought, actually, once a week to every ten days should suffice for a established tree, providing the watering is done properly. Trees that are 5-10 years old or more are considered established trees, depending upon the type of tree, and these trees are much more likely to survive an extended drought than newly planted trees.
Don’t waste water watering at the trunk of an established tree. The hair roots of the tree, which take in water, are at the drip line, which is the outer edge of the branches and beyond. When watering trees, water the entire area under the canopy, especially the outer edge of the limbs.
All trees are genetically programmed to help survive drought stress. Some will shed leaves to conserve water loss, others will sacrifice new limbs in favor of older established limbs. Still others will grow a waxy coating or a pine resin on the leaves or needles to reduce water transpiration. Certain types of trees need more water than others, such as Birch, Tulip, Adler, Pin Oaks, Poplars, and Silver Maples.
All plants handle drought stress differently, but the most obvious sign is the wilting of the leaves. Wilting happens when the leaves lose more water than the root system is taking in. Even with proper watering and soil moisture, some plants such as hydrangeas, will wilt during the day in high temperatures. However, at the end of the day when the sun goes down and the temperatures drop, most plants will recover rather quickly. However, container plants that start to wilt, most likely need a good watering.
Established trees and some shrubs are less likely to wilt, but they will show signs of water deprivation. This is generally called leaf scorch. Leaf scorch can be identified as the browning of the leaf edges and also between the veins of the leaf. The contrast between the normal green color of the leaves and the leathery or crisp feel of the leaves will be an obvious indicator of leaf scorch. In general, the tree will show signs uniformly over the entire branch, not just parts of a branch. If the plant suffers from leaf scorch long enough, leaves or entire branches may die.
Soaker hoses are a great way to water if used properly. Most soaker hoses however, don’t soak the soil as deeply in the same time as other methods, so they need to be used for longer periods of time. To use soaker hoses in the best way, allow them to run overnight and turn them off in the morning, this will allow sufficient time to saturate the soil around trees and large shrubs. Soaker hoses are excellent watering devices because they deliver a slow, steady soak to just the areas you want to water (the roots) without wetting the leaves.
With the cost of watering in a drought, every drop of water counts. To guarantee sufficient water within your budget or local town restrictions, use a rain gauge to monitor how much water you are giving each plant or the lawn. A lawn gauge is not a requirement, any straight-sided can or pan will do. Place these gauges on the lawn or in the beds and time how long it takes to reach the appropriate inches of water you need for the plants you are watering. Remove the gauges when after you measure.
Container Plants & Hanging Baskets
Above ground container pots, planters and vases are like ovens in high temperatures. The pots or planters can heat up very quickly and often are hot to the touch. The plants in these containers are often stressed more and faster than plants planted in soil beds, and hold much less water for the roots to absorb. Move your containers into a shady area and water 1” at least three times a week.
Crowded Beds Compete For Water
Fully planted beds, or beds planted under trees are always an area that requires more water. Every plant in a crowded bed is competing with the other plants for the available water. The plants in a crowded bed should be watered significantly more than an open, well mulched bed or stand alone tree.
Fertilizing and Mowing
Against what may seem sensible, avoid fertilizing plants and lawns during times of drought stress. Fertilizing promotes plant growth, which requires more water. The blades of grasses in lawns in a dormant state are not actively growing, and should be left in a dormant state.
Mowing of lawns should be reduced to a minimum, and only in the shady areas where some growth may occur. Mowing of the lawn should also be avoided because of the stress that foot traffic and the weight of the lawn mower can add to an already dormant lawn.
Plant beds should always be mulched for numerous reasons, but during a drought the mulch will help cool the roots and retain the minimal moisture that the plants are receiving.