The heavy, steady rainfall we had recently in Scotch Plains only totaled about .8 inches. Newly planted trees and shrubs need a full 2 inches of water per week to keep them healthy. So no, even if it's raining, the rainfall isn't always enough.
No, your lawn sprinkler system is not adequate, either. Nor is standing with your hose on full pressure for 15 minutes. The major cause of death for newly planted trees and shrubs is under watering and over fertilizing. If I had a dollar for every time I say this to people buying large plants, I'd be able to buy you all soaker hoses.
New plantings need slow, deep watering for their entire first growing season. Natural rainfall may be enough to hydrate plants that germinate from seed in their native habitat, but it's NOT enough for a tree in a two gallon or larger pot. It is essential to provide water in a manner that allows it to percolate down to the base of the root ball. If the water pressure is too high, if the water is flowing too fast, it will run off before it has a chance to soak down to where it needs to go.
Shallow watering will encourage the roots to stay right under the soil surface. When the winter sets in, those shallow roots will freeze and thaw repeatedly and the plant will sustain damage—if it survives. To get your plant, tree, or shrub to thrive, it needs water to the bottom of the root ball a couple of times a week all season.
One of the easiest ways to keep your new stock watered is to purchase and install a soaker hose. This is a porous hose that allows water to seep out at a very slow rate. You can lay the hose under the plants or in a circle around a large tree or shrub. A few landscape staples pressed into the soil will hold the hose in place. Cover the whole thing with mulch and you are good to go day or night with no visible hardware. Set a simple timer up to the spigot and you have no time investments to worry about, either. Parker Gardens carries soaker hoses, as do other local nurseries and most of the big box stores.
Another super cool idea for watering larger plants is the Tree Gator or Gator Bag. This is a heavy plastic ring-shaped bag with a valve for water input. The bags come in two sizes: 15 and 20 gallons. You fill the bag from the hose when it gets empty, about once a week usually, and the water slowly seeps into the soil to keep the roots moist. Many townships are using these bags when they plant new street trees. These are a great idea if you are going on vacation and want your water shut off while you're away.
It is not necessary to measure the water exactly, but it can be fun to do with rain gauges. They are simple, decorative devices that collect rainfall in a cylinder that is marked for measurement. Measuring rain is always a fun activity for children. Scotch Plains rainfall averages are easy to compute and a fun way for young minds to practice their "school skills" during the summer months.
Want to stay green and save on energy bills? Buy a rain barrel to collect the free falling water. A few styles are available at Parker Gardens and other garden supply stores in the Scotch Plains-Fanwood area. The simple technology can create significant savings as well as make your chore of watering easier and more convenient. They are non-obtrusive, very practical and kind to the environment.
If you are uncertain how often or how long to water for your individual needs, feel free to drop me a note on this Facebook page and I'll try to answer your questions there. The danger of over watering is slim. The repercussions of under watering are great.
Editor's Note: Janet M. Dillon works for Parker Gardens in Scotch Plains.