Watering is the one site condition that you as a property owner have control over. While you can't control shade and sun, temperatures, or soil types, you can affect how much water your plants, shrubs, and trees are receiving as they prepare for winter dormancy. By taking care to water your landscape well going into winter, you are helping to preserve the investment that you have made so far into your landscape.
When to Water:
We would recommend continuing to water your landscape up until the ground freezes, which occurs on average around the middle of December.
As far as frequency of watering, a deep watering once every week or so should be good for established perennials and smaller shrubs. Larger established shrubs and trees can probably just get three or four deep waterings between now and 12/15. Plants that were installed this year, especially those that have been planted since July, should be watered deeply every few days.
How to Water:
Additional watering can seem like a lot of work if you have in-ground irrigation that has been turned off for the season. If you don't have an irrigation system, it may feel like a huge task to try to get adequate water to all of your gardens, so in either case, consider these tips:
Do you need to set up a sprinkler to water a large area all at once?
A sprinkler is a great choice for watering multiple perennials in a larger area as it allows water to soak in around all the plants in an area. It may not be a good choice for watering shrubs as you would be watering for a long time in order to get the water down to the level of the roots.
Consider setting up a sprinkler for an hour or two at a time, every week or so for established garden spaces, and every day or two for newer installations.
Do you have the time to set a hose on a slow trickle and leave it at the base of larger shrubs and trees for an hour or so at a time?
Trickle watering is a good choice for shrubs and trees as you can water very directly at the base of each plant, thereby reducing water waste. This may require a reminder to move the hose and shut it off when you're done, but pairing it with another time-based task such as doing laundry or running the dish washer can help you stay on top of it.
Trickle watering really only needs to happen every two or three weeks for established shrubs and trees, since it allows water to seep in deeply, where the roots have a chance to soak it up over several days.
Evergreens in particular require irrigation to help get them through the winter. Because they do not drop their needles, they lose quite a bit more water content over the winter than their deciduous counterparts do. In order to help them survive winter as well as prevent sunscald, windburn, or winter burn, be sure to deeply water your evergreen trees and shrubs before winter.
Finding watering solutions may look different for every garden, but they will provide a huge return on investment for the health and longevity of your landscape!