One of the more common questions we are asked by customers is how to water their landscaping. Although many people
wish there was a concrete schedule by which to follow (e.g. twice a week), unfortunately there is not. In general, new
plantings need to receive one inch of water per week. Water can be provided by nature, handwatering, or an irrigation
system. In Central Indiana, summer rarely provides rainfall that is perfectly timed to meet the needs of landscaping
plants, so supplemental irrigation is almost always necessary.
Factors influencing the hydration of your landscape plants
Plants in differing soil types will vary highly in their water needs. In our area, most soils have a high clay
content which tends to stay wet and drain poorly. If you properly amended the soil before planting, you probably improved
the soil's drainage ability, so overwatering is less of a concern. However, your soil type may vary widely depending
on exactly where you live. Pay attention to the soil type you have and its implication on your irrigation needs.
Sticky clay soils (you can easily roll the soil into a ball in your hands) traps water and can easily suffocate plant roots.
Gritty, sandy soil (rare in this area) acts like a sieve, losing water to drainage soon after it's applied.
Mulching helps prevent the evaporation of water from the soil surface. Plants in mulched beds will be less demanding of
supplemental watering. Also, hot, sunny beds tend to require more irrigation than plants in a wooded lot. An exposed
windy site will dry out rapidly while a garden in a low-lying area may stay wet. Finally, summer weather can be unpredictable
- use a rain gauge to track exactly how much water you are receiving in your yard (weather centers only report
rain received at specific weather stations). Isolated storms characteristic of mid-summer can deliver
one or two inches of rain in one spot, while just a mile or two away, not even a drop will fall.
Temperatures also greatly influence plant watering needs. Cooler temperatures and cloudy days generally create
less evaporation, so less water is required. Hot temperatures promote evaporation. High humidity (often coupled
with high temperatures) can tend to keep your garden on the wet side, and the heavy moisture in the air greatly
contributes to the development of foliar diseases promoted by evening watering.
The type of plant planted also influences its watering needs. Plants that were in pots before they were planted
in the ground are in a loose soil mix that drains well and may require more frequent watering than a balled and burlapped
specimen. Balled and burlapped plants are grown in clay soils and are more prone to overwatering.
How to water
An important principle to remember when watering landscape plants is that slow, infrequent, deep watering
is most beneficial. Shallow, frequent waterings promote shallow root growth, increasing the plant's dependence on constant
irrigation. There are many methods to water - sprinklers, hand-watering, and more. If you have new landscaping
that is not yet established and do not have an irrigation system, periodic meticulous handwatering is probably best.
Use a hose attachment that delivers water like a shower rather than a forceful spray (we like Dramm watering wands, available
at your local hardware store) and soak the plants individually, including the surrounding soil. Remember that the roots
of newly-planted trees and shrubs have yet to venture beyond their original root balls, so direct the majority of your
spray directly over the area where the root ball is.
There are a few plants which you should avoid getting the foliage wet because of foliar diseases. These include
roses (especially disease-prone hybrid teas and floribundas)and old-fashioned tall phlox. Watering early in the day,
especially if you must get the foliage wet, is a way to avoid this problem.
Soaker hoses can be installed to water plants without wetting the foliage, but they are not for everyone.
They are only effective if used properly. Be sure to follow the directions on the package if you choose to use them.
Lay them out as required (you may be surprised how much yardage of hose you will need if you space them as directed).
Also be sure to run them for the recomended time on the package.
If using a sprinkler, use a rain gauge or empty soup can to measure the amount of water provided during your watering
sessions. Stop the sprinklers when you have delivered your 1" per week quota (remember to track rainfall for the week
and subtract this from your irrigation amounts). Using a sprinkler is more suitable for established lawns or established
landscaping in which the rootzones of plants are more widespread, although it will do for watering new landscaping for the
homeowner that is short on time.
If you have an irrigation system, your service provider can help you determine a proper watering schedule,
and set up your system to do so.
When to water
When in doubt as to whether or not a plant needs to be watered, follow the cues that the plants and surrounding soil
provide. Feel the soil (under the mulch) surrounding the plants and check for moisture. If the soil is moist -
watering is probably not necessary. If the soil is dry (and especially if the plant is wilted), you probably need to
water. Wilting is often a sign that a plant is dehydrated. However, wilting can also be caused by other physiological
problems, stress, or intense heat. Do not immediately water a plant just because it is wilting. Take the time
to feel the surrounding soil first.
What time of day should I water?
Morning watering is probably best. The water does not rapidly evaporate, foliage has a chance to dry before evening
reducing the chances of foliar disease, and plants are prepared to endure the stress of the daily heat. It
is a myth that watering during mid-day can 'burn' your plants (no such phenomenon exists), but mid-day watering is less than
ideal because a lot of the water delivered is lost to rapid evaporation. Watering during the evening may promote fungal disease
and a harmless but revolting-looking mold on your mulch, and should be avoided if possible. However, it is common sense
that if a plant desperately needs water - then water it! Don't worry about whether or not it is the ideal time of day.
Too much of a good thing
We find that many people overwater their plants. When a customer seeks our help regarding a dying (or dead) plant,
our first question is, "How often are you watering?" The answer is more often than not: "Everyday". Watering
every day is most often a death sentence for new plantings. Yes, you can kill a plant with kindness.
Plant roots need oxygen to survive, and watering constantly without allowing time for the excess to drain off often submerges
the roots, creating root death. Massive root death means plant death, and many homeowners are left wondering what they
There are a few cases where watering every day is acceptable, but only a few. If you have windowboxes, pots, or
planters, (if they have drainage holes) you may need to water them everyday in the later days of summer once the plants are
well rooted in. Environmental factors also greatly influences how fast a pot will dry out (see Factors Influencing the
Hydration of Your Landscape Plants above). Watering pots everyday (if they are drying out everyday) is acceptable and
may even be necessary.
Newly planted flats of annuals, small pots of annuals or groundcover, and perennials may need daily or frequent watering
when they are newly planted, but only in some situations. Follow the environmental cues (especially soil moisture) to
help decide when to water them. As their roots become established, you should scale back the frequency of your watering.
As you can see, the principles of watering are actually very simple. Take the time to tune into the specific needs
of your landscaping plants, and adjust your watering to accommodate these needs, taking into consideration the precipitation
that nature has provided. Above all, resist the urge to implement a "watering schedule" and let your plants and soil
be your guide.
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