A little cold, slightly below freezing, only zaps foliage. I just had 27F last week. The leaves turned a sorry looking, dark green to almost black ugly color but, that was the extent of the cosmetic damage.

To further protect the shrubs, I maintain 2-4" of mulch and water dry soil deeply the night before these temperature dips (or bigger dips).

Flower buds can be harmed at lower temps so be ready to add winter protection to hydrangeas that bloom on old wood so the early Spring flowers' buds will not be killed.

Isn't it good practiveto keep laying off the water so that you can sorta force it into dormancy at this point in time. Soil just damp enough so the roots don't dry out, but no water ?

Yes, if the soil is already damp enough that the plant can absorb water from the soil then you are good to go. Otherwise, water it. I assume your soil does not freeze or has not frozen.

Luis -

For clarity, what I meant per the reply was if a plant is now in the season to go to sleep, don't you want to hold back on the water (especially now that the cold snap has already given it a reminder to go to sleep) just to help it go into dormancy ?

Heh, I have this row of extremely slow sl0w growing green velvets. Those are like my toddlers. They do maintain their green all season long though. I baby these things. They get wilt pruf during this time of the year. I do try to keep the soil just wet enough giving them a drink in between non freezing days.

Even when it's like a dead of winter, and there looks to be a couple of days above freezing, I'll put the snow boots on and dive into white hotmess, just to give each rootball a small drink

"For clarity, what I meant per the reply was if a plant is now in the season to go to sleep, don't you want to hold back on the water (especially now that the cold snap has already given it a reminder to go to sleep) just to help it go into dormancy ?"

Lack of water inducing dormancy is not a botanical phenomenon I have ever read about nor encountered personally! If it played a significant role in this activity, few of the plantings in my area would ever go properly dormant..........the start of the rainy season here coincides with the time most plants are considering entering dormancy!!

Dormancy is most often associated with climatic conditions - temperature and photoperiod declines. Sometimes temperatures can remain very mild late into the season and that can slow the foliar change, as the plant continues to make use of its resources. An abrupt change in temperature will force the issue but it removes some of the normal processes we are used to seeing.......leaves changing color, senescense and dehiscence.......instead we often see dead, dried brown leaves that remain attached to the plant. But that doesn't mean the plant is not dormant or well on its way to be dormant.

There is actually a botanical term that describes this situation - it is called 'consequential' dormancy or the entering of dormancy after adverse conditions have occurred. This is in contrast to the more common 'predictive' dormancy we are used to seeing, where plants start to enter this biological phase before any adverse conditions.

I hold back on the water when they go dormant. Program your drip differently according to avge winter conditions. I make the change usually around the end of December or in January when hydrangeas go dormant, although some hydrangeas stay awake all year long due to mild winters. Once they go dormant, you can reduce waterings to once every week or once every two weeks but it depends on whether winter is dry or wet so I regularly check with the finger method before I tun on the drip in winter. Lost one hydrangea during winter one year when the drip irrigation had issues and was not working. I noticed a camellia browning its leaves instead and that alerted me to ck for problems with the drip. But the hydrangea did not come back. Oh well.

But regarding freezes, I water the night before if the soil is dry:

https://www.todayshomeowner.com/when-to-water-plants-before-a-freeze/

The weather prognosticators say this winter will be influenced by a La Nin~a Event that, in my area, means it will be warmer than normal and drier than normal so... I will be keeping an eye on soil moisture and will be expecting less precipitation. But with my luck, those times that actually get precip will get ice or snow instead of plain ole' rain!!! Oh, meee. LOL! Hee hee hee.

I will water evergreens going into freeze if it's been a dry summer and fall, especially if they are relatively newly planted in the last couple of years. Generally, however, we have enough natural precipitation during the fall, and I am more likely to be concerned about the amount of ponding water in the spring held in place by frozen soil and even after thaw the combination of snowmelt and rain can make for sodden soil for quite some time. So whether one needs to water before it gets cold most likely has to do with one's climate and how moist one's soil is rather than any particular rule.

In many areas protection from sudden dips in temperature after the buds have started expanding in spring is important to the year's successful flowering, and in really cold areas like mine, winter protection all winter is important to consistent flowering.