Watering Plants – How, When & Why
Proper watering is an important part of gardening. Lasting damage can occur when leaves and stems wilt. Regular watering helps keep plants and trees growing. Flower and fruit the following spring will be much better with regular watering, and so will fall color. Vegetable gardeners know that even short periods of dryness will permanently stunt some plants, limit fruit size, and cause plants to bolt or go dormant too soon. Landscape plants are no different; they’ll thrive much better with well-timed watering.
Many people simply depend on the rain for watering, but normal rainfall isn’t enough to sustain newly-installed plants accustomed to daily watering in the nursery, or vegetable plants that are actively growing. Even established plants can struggle in hot, dry weather. Timing is everything, and rainfall can’t be counted on to get the timing right. Rain often just wets the surface and still the roots can be bone dry. Even an inch of rain won’t soak in deep enough to help larger woody plants.
How much should you water? The best advice we can offer is that plants should be thoroughly soaked whenever they get dry. Plants breathe through their roots, so if they are constantly soaking wet they will drown and the roots will rot. For this reason, most plants prefer to dry out a bit between waterings.
Newly planted shrubs, perennials and trees struggle to get established when temperatures are in the 90’s and drying winds keep us busy with supplemental watering. Until they grow new roots, newly-installed plants need regular watering as often as once a day.
When you plant new plants, be careful not to cover up the container soil or root ball with soil. Instead, try to shape the soil around the plant into a bowl or “well” to hold water close to the plant. The bigger the plant the larger the well should be. This keeps the water from running off before it has a chance to soak into the roots. Now simply fill the bowl once a week, or more often for plants that are visibly wilting.
Established plants need attention during drought. Even if they can survive without watering, plants and trees will benefit from occasional deep-root soaking. Drought causes stress that invites insect and disease problems, some of which don’t show up until years afterward. Set your hose to a trickle and lay it next to the trunk for a few hours.
We’re often asked whether it’s OK to water during daylight hours, or in the evening, or at other times. Our answer is simple: water when plants are thirsty, whenever that is. Yes, it’s possible for water droplets to magnify sun rays, leaving little scorch marks on the leaves. Yes, if certain plants are wet overnight in hot, humid weather it can invite fungus diseases. But wilting from dryness is much more likely and more damaging, so it’s best to water whenever plants need it and you have the time. Aim the water at the base of the plant; wetting the foliage doesn’t help and can cause problems.
“Tree Gators” are an easy way to make sure newly planted trees get enough water. These are special bags designed to zip around the trunks of trees. They hold 14 gallons of water, trickling it gently into the root zone over an 8 hour period. Filling each bag takes only a few minutes, and once per week is usually enough.
The right watering tool is important. Pistol grip nozzles are for washing cars, not watering plants. They hold back the water and make watering take much longer. Instead, we use an industrial “ball valve” (Dramm #300 Brass Shut-Off Valve), and a professional model water breaker (Dramm 400AL). What makes these tools superior is the wide opening that doesn’t restrict water flow, and the gentle soaking action of the water breaker spray. If you don’t own a water breaker, just unscrew your pistol-grip nozzle and use your thumb to break the flow.
Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are on the “Garden Advice” page at www.goodseedfarm.com. For more information is available at www.goodseedfarm.com or call GoodSeed Farm Landscapes at (937) 587-7021.