Garden Update
Week of August 29, 2022
Kathleen Cue, Nebraska Extension Horticulture Educator in Dodge County
The Deepening Drought
Even with the much-appreciated recent rains, it isn’t enough water to lift the region out of drought. There are some changes we can implement to help plants while still making the most of the water we have.
What to Water
For landscape plants, priorities for watering are placed in importance: 1. Plants planted within the past 5 years, 2, Evergreens and orchards, and 3. All other plants. New trees and shrubs are watered 3-5 gallons per caliper inch (the trunk diameter in inches) per week. Evergreens and fruit trees, along with all other landscape plants, need an inch of water, applied all in one application, per week. Be aware that dwarf and semi-dwarf fruit trees should also be watered. These plants derive their reduced size via a root system that is smaller than full-sized fruit trees, thereby tapping less soil volume for water. Depth of water percolation, rather than frequency of watering, is more important for trees and shrubs, whereas irrigation systems deliver frequent shallow applications of water to turfgrass. A quick and easy method of checking soil moisture is to push a screwdriver into the soil. Soil that is dry will be difficult for the screwdriver to penetrate while a screwdriver that easily pushes into the soil means soil moisture is good.
Put off Fall Planting
“Fall is for planting” is a popular saying among plant enthusiasts but is it really practical, given the low soil moisture? It depends. If new plants are close to a water source, then watering may not be such a big job, but if new plants means lugging water from a distance, then putting off planting that new tree until spring is a wise choice. If you do plant this fall, a zip up watering bag or a watering donut are useful tools to provide drip irrigation to newly-planted trees and shrubs. These devices can be filled with water and small holes in the bottom of the device emit water over an extended period. You can also make your own drip irrigation device by drilling four to five 1/8 inch holes in the bottom of a five-gallon bucket, and then placing the bucket near the base of the tree. Fill the bucket with water to slowly drip around tree roots. Putting a brick or stone at the bottom will keep the bucket from blowing away in heavy winds.
Mulch
Nothing keeps water in the soil from evaporating like mulch. Not just any mulch but shredded bark or wood chips is best. Wood mulch should be 2-4 inches deep and not piled against the crown of the plant. A minimum mulch ring should extend out 3 feet from the trunk and even further for large trees. Forget the landscape fabric, plastic, and rock mulch as these things interfere with the exchange of gases at the root zone and keep roots hotter than areas without them.
Delay Fertilization of Dormant Cool-Season Grass
If the Kentucky bluegrass lawn has been allowed to go dormant over the summer months, be sure to skip the September fertilization. Fertilizer salts can burn roots making it harder for dormant turf plants to recover once rainfall returns.
Put In a Rain Barrel or a Cistern
Water that is shunted off roofs and pavement is lost when moved into storm sewers. Instead, take advantage of this free water by utilizing downspouts to funnel water into rain barrels or cisterns. Less than a .5 inch rainfall is enough to fill my two 50-gallon rain barrels, which is a boon for watering my gardens.
Irrigation systems
Rather than have the “set and forget” approach for the irrigation timer, check first to see if water is needed. It doesn’t make sense to water the lawn when it’s raining and it is not good for plant roots to be watered every day, even if it is hot. Correct uneven watering by simply watching the system run, making note of anything requiring fixing—and then fixing it. Consider putting in a drip system for landscape beds and vegetable gardens. When a water droplet is lofted through the air by an overhead irrigation system, some water never reaches plants, instead being lost through evaporation. Drip irrigation delivers water right where plants need it with minimal water loss from evaporation. Trees, shrubs, flowers, orchards, and vegetable gardens can have their water needs met while water is saved.
Apply Anti-Desiccants
Plan this fall to apply an anti-desiccant to the foliage of evergreens to minimize water loss during the winter months. Anti-desiccant products deliver a thin layer of plastic or wax, protecting needle-type and broadleaf evergreens from winter leaf burn.
Choose Native Plants
Native plants are highly adapted to periods of wet as well as dry. Converting more of the landscape to native trees, shrubs, wildflowers, and grasses means good-looking, high-performing spaces that benefit pollinators.
Find more horticulture articles at Trees, Plants and Insects
Above is a Nebraska Forest Service photo showing drought stress on trees.