The hot, dry periods that often occur in central Ohio weather patterns can present a real challenge to anyone who is trying to keep trees, shrubs, flowers, and lawns alive and healthy. Here are some proven ways to help outdoor plants grow and stay healthy during periods of time when there is little or no natural rainfall.
First - add a two-inch thick layer of mulch on top of the soil around the trees, shrubs, ground covers and flowers, and vegetables. Shredded bark is the best kind of mulch for trees, shrubs, ground covers, and flowers, but aged wood chips, leaves, straw, or similar organic materials will also work. Leaves or straw are good mulches for vegetables. Mulching is very beneficial to plants because evaporation of water from the soil is greatly reduced, the soil stays cooler, and competition from weeds is reduced. One direct result of a good mulch is the significant reduction in the amount of supplemental water that plants need during hot, dry periods. Mulches are most beneficial when applied at planting time, with more being added as needed to maintain the desired thickness.
Second - check the moisture in the soil under plants at least once a week whenever the natural rainfall might be inadequate. Don't guess or make assumptions about soil mixture. The only sure way to check soil moisture is to put your hand down into the soil under the mulch (use a tool to dig a small hole if your need to) and feel the soil. If the soil is sticky and it feels wet or moist, then there is enough water in the soil. If the soil is powdery and it feels dry, then water needs to be added as soon as possible.
Third - water plants wisely when soil moisture is found to be inadequate. In general, wise watering means:
a) Soaking the soil deep down (as far as the plant roots go) and then waiting again until the soil is again dry or nearly dry. This method encourages plants to grow more vigorous, deep roots that tolerate dry spells better than plants with shallow roots.
b) In hot weather, water early in the morning or in the evening when the temperature is cooler; this method will conserve water because less water will be lost to evaporation and more will soak into the ground.
c) Use a small sprinkler or slow-running hose that gets moved to several places when watering individual trees or shrubs; use larger sprinklers or sprinkler systems when watering planting areas with many plants or on lawns.
d) Adjust the water flow so that little or no water runs off the surface of the area in order to eliminate waste.
e) Make sure that the water only goes on the plants that need it.
f) Turn the water off when the soil is soaked deep enough (six inches to two feet depending on depth of plant roots) or when the water is running off instead of soaking in (mulch also helps water soak in since water often just runs off bare soil).
g) In hot dry weather and, or during restricted water use periods, the plants that are the most important ones to water are newly seeded or sodded lawns (for the first two to four weeks) and then anything else that has been planted recently, next most important are established trees, shrubs, ground covers, annual and perennial flowers, and vegetables; established lawns are least important because grass plants can survive long dry periods by dormant (brown).
h) In addition to checking soil moisture by feel, one way to judge how much water to apply is to measure both the natural rainfall and supplemental water by using a rain gauge under sprinklers and using these guidelines:
Established Trees and Shrubs:
| Temperature |
Optimum |
Moderate |
Minimum |
| Up to 65° F |
1/2"/week |
1/2"/2 weeks |
1/2"/month |
| 65-85° F |
3/4"/week |
3/4"/2 weeks |
3/4"/month |
| Over 85° F |
1"/week |
1"/2 weeks |
1"/month |
These recommendations are generally required for each 1" of tree caliper, or per 3' of shrub height.
Ground cover plantings, annual flowers, perennial flowers, and vegetables:
Apply 1/2" twice a week on new plantings until plants are well rooted (2-3 weeks). Apply 1/2" of water to established plantings whenever the soil checks dry.
Newly Seeded Lawns
Water to keep the seedbed moist (up to three times a day) for at least three weeks until the grass is four inches high, then reduce watering to established lawn rates.
Newly Sodded Lawns
Soak new sod immediately after it is laid. Then water every day for the first two weeks, and after that reduce watering to established lawn rates.
Established Lawn Areas: Optimum watering
| Up to 65° F |
1/2" of water per week |
| 65 to 85° F |
1" per week |
| Over 85° F |
1 1/2" to 2" per week |
The optimum amount of water for ideal turf growth is the amount that it takes to keep the entire root zone (usually 8-12") moist (not wet).
Less than optimum watering - when lawn watering is restricted but still allowed on a limited basis:
| Up to 65° F |
up to 1/4" of water per week, including natural rainfall |
| 65 to 85° F |
1/2 to 3/4" per week |
| Over 85° F |
1" per week |
Happy Gardening!
Bloomin Garden Centre & Landscaping
8793 Kenwood Road, Cincinnati OH 45242
Garden Store: 513-891-9035
Landscaping: 513-984-TREE
Fax: 513-891-9276
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