To ensure that your plants make it through the winter, it is important that they receive adequate moisture now. In autumn, plants repair their roots, grow their tree trunks, and develop flowers for a beautiful display next spring.
You can sustain the health of your plants by watering well this fall. Trees, shrubs, evergreens, and groundcover planted within the last two years should be considered newly planted, and are particularly susceptible to winter stress. Even if leaves have fallen, plants’ roots continue to grow and watering is important until they go into winter dormancy.
Watering should penetrate 8” – 10” into the root zone to be adequate. This means at least one hour of watering with a typical sprinkler. A measured inch of water will do the job. Put a pie plate in the area being sprinkled so that you know when a full inch has been applied. This may involve soaking your plants with a hose or sprinkler for several hours.
Trees and Shrubs: Place the open end of the hose at the base of the plant and allow it to gently flow into its root ball. The rate of flow should be such that it soaks into the soil without running off or puddling. You can water each plant individually, 5 to 10 minutes per four feet of plant, or place a sprinkler to cover the area for 3 hours.
Groundcover and Perennials: Because these plants have much smaller root balls than their woody companions, a sprinkler is probably the easiest way to water them.
Water throughout the growing season, the time between the last frost of late winter up until around Thanksgiving, for leaf and root system development. Temperatures should be above 40 degrees Fahrenheit.
With cooler autumn days, watering should be done once or twice a week. Nature helps out by providing rainfall. Check the weather report. If an inch of rainfall has fallen, you can take a break from watering for a week.
A plant root ball can be completely dry even though the soil and mulch surrounding it may be moist. The best method to check if the soil is moist is to get down on your hands and knees and check the root ball with your finger, a small trowel, or a knife. Be careful not to damage any roots.
You may be tempted to turn up the water flow to get the watering done more quickly. You may be able to do this to some extent, but it is important that the water soaks down into the root ball and does not run off to the side and soak down into surrounding soil. Keep the water flow turned low to the point that the water does not run off.
Too much water is as dangerous as too little. In fact, on sites with poorly drained soil, more new plants die from overwatering than underwatering.
Finally, remember to turn off your water from the inside, and disconnect your garden hose from the outdoor spigot. The outdoor spigot should be left open to release water and prevent the pipes from freezing during winter. Store your hose in the garage to protect them from freezing.