in my zone 5 .. the suspended animation of total ground freeze .. makes the issue moot ...

the only caveat.. is that roots need air .... and you want enough drainage late in fall.. so that nothing freezes its roots into an ice cube ....

other than that.. maybe you have been reading too much .. because i dont know why a totally dormant plant would care about its roots/feet being wet ... one of the problems is.. perhaps.. that you dont know where the author of that wisdom is located.. to me.. it sounds more like a warm6 z7 issue.. not here in the great white north ...

soooo.. who wrote the book and where are they????? ... please dont tell me its british ... lol ...

or i am wrong ... hmmmm ..

ken

ps: btw .. what plant????

I lose plants in winter here that are hardy to far colder zones to do poor drainage. Of course, it rains for weeks on end here....

Are we talking about winter wet?

Winter wet refers to a location in which alot of snow accumulates and tends to drain much more slowly (typically late winter thaws) than it would during the growing season. It doesn't necessarily mean its a location that would have poor drainage during the growing season.

Think of areas with snow banks.

Basically what I'm asking is how do you protect plants in winter that like good drainage?? You can't really prevent snow from hitting an area...

I have biggest problem with slow drainage and melting snow up by the street where you get those 4-5 foot banks of icy snow pushed up by the plows. I plant herbaceous perennials and hope the roots can take slow drainage in late Winter and early Spring when things melt. Things don't love it right up by street but enough for some flowers and fill in with annuals.

Just think of where the plant grows naturally and you'll know what would work best in heavy icy snow melts. Prairie, woodland, scrub, slopes, Mediterranean, etc.

We all put things in our gardens that wouldn't grow there naturally and see what works in our typical weather conditions. After 2 blizzards last Winter, heatwave June & July and drought July through present and plants whose roots survived melting ice are additionally stressed this year.

One thing you can try is mounding things higher when it says they don't like "wet feet." Lavender grown for oil is planted in long mounds so its roots are higher than standing water. Then again most lavender isn't grown for oil in Zone 5 for a good reason other than wet feet.

You can try mounds of good soil with wells for when you want to water outside of Winter melts and heavy Spring rains. You can also dig a bed specifically for things that don't like "wet feet", line it with gravel at bottom and backfill as raised bed with well draining soil.

That way you at least try to replicate a plant's natural growing conditions. Some plants are more finicky than others so it's difficult to know beforehand what will work for your situation.

Some people don't want to mess with special growing conditions and others want what plants they want. Sometimes they survive with a little help from the gardener and sometimes nature has her way with plants.

Mostly you can tell by the fact that plants that are considered reliably hardy in your zone, & grown by many people here on the forum in your zone, DIE in your garden over the winter, either never returning in the spring, OR by trying to return in the spring by sending out one sickly sprig & then quickly dying off, & they do these things for you over multiple attempts at growing them. Believe me I have plenty of experience with this.

Why this happens is somewhat a matter for speculation. My experience has been that plants labelled with cautions about drainage (beyond the "moist but well-drained" nonsense that is on so many labels) may have considerable difficulty overwintering in my garden, despite zone compatibility. In addition, plants labelled for zone 6, which some people around here can grow, will almost NEVER survive winter for me, unless planted under the eaves at the highest point in the yard. Zone stretching is painful here.

I blame this on "winter wet". My definition is somewhat broader, however, than Whaas's is. I can have this problem just about anywhere in my yard. I garden on very heavy compacted clay - where everything drains slowly. I have gardened on this clay (I still don't call it soil) for over 15 years now, constantly amending & improving it, with some gains, but a lot of plant losses.

In very cold, consistently cold weather, with good snow cover, my losses are now usually slight. In a year with freezes, ice storms, occasional snow cover, odd warm spells, followed by winter as usual, losses are high. My theory is that many of these plants survive my winters, just not my sometimes nasty autumns & wicked springs.

To combat winter losses I use every trick in the book. Amending soil & planting under the eaves I have already mentioned, & raising beds is certainly helpful, along with selecting plants that are moisture loving (remember most of these still need some air in the soil), always picking major shrubs and trees compatible with clay, & planting high, using mounding & little shelves, etc.

I find that rock works the best, big rocks, little rocks, gravel & grit & granite fines, in the soil and on top of the soil. Commercial products like Profile (fired ceramic bits) can do wonders but are expensive. We could not keep a front curb tree alive in our (very non-urban) setting (probably because of the piled snow Whaas mentioned, rather than the dry heat so often associated with these locations) before we discovered it. A mailbox planting is out of the question, I'd have to raise the mailbox too high for the mailman. :))

in my z5.. the trick is ... GET THEM DORMANT ... KEEP THEM DORMANT ....

the biggest problem is freeing.. and thawing.. and re-freezing .... re-thawing ... etc .. ad nauseum ...

i used to joke that a hybrid t roses .. would laugh if it happened once.. be damaged when it happened again.. and commit suicide on the 3rd time .. and then i quit growing those foo foo roses and life was so simple.. lol ...

tissue just cant take those couple of 50 degree days in feb .. and go back to 0 at night ... over and over again ...

the issue with a black pot in such.. is that the roots go from fully dormant.. to thawwed .. because the pot in the sun thaws the media and the roots over and over again ... its like a banana in a freezer ... yuck ...

and then add any additional water to thawed roots.. and you get rot .. and when unthawed roots are exposed to too much thawed moisture.. rot happens.. and things die ....

so in the great white north.. with plants in the ground .... we add layers of insulating mulch to temper the freeze thaw possibilities of winter .. and thereby manage the moisture with a plant in suspended animation ...

if we have a full snow cover year ... we have little problem .. because snow is the best insulator.. and provides some amount of water underneath ...

the problem are those winters without reliable snow cover.. when the sun can warm dark soil and freeze and thaw becomes an issue.. so we heap loads of compost or mulch over the tender plants.. that need the insulation ...

if the plants are in pots.. your best bet.. from my experience.. is to go out.. around thxgvng .... and lay them all on their sides.. on the north side of a structure [NO SUN on those pots.. period] .. even stacking them.. so they get frozen.. and stay frozen.. and water accumulation is minimum because the tops are not exposed ...

and if they are tender plants.. you cover the whole pile in mulch, compost or hay .. to reduce wind also ...

the real key .. as i said.. GET THEM DORMANT.. AND KEEP THEM DORMANT ....
so your specific question about winter moisture in your z5.. is highly complicated by all the other winter variables.... and that is why you are struggling ...

ken

ps: your never told me if this was an english book??? or where the author is from ... because i have a theory i can share...

"Basically what I'm asking is how do you protect plants in winter that like good drainage?? You can't really prevent snow from hitting an area..."

You just about answered your own question.

You can't plant perrenials that are intolerant of wet feet in areas where drifts occur...or snow banks...or areas where the water drains to during thaws and freezes.