Care over the winter...

It may look like a Christmas card, but this photo was taken
in the second week of November, 2017! This is the
view at Wildwood Gardens, the bonsai nursery in Northeast Ohio
run by Frank Mihalic. Winter came early this year!

It’s that time of year-time to consider winter storage for our trees. This is a topic that can cause lots of agitation and confusion.  Here’s a few thoughts on winter prep to bear in mind.

First step-consider the needs of the trees. Bonsai fall into three basic categories as far as winter care:

1.       Fully hardy. The plant can cope with any temperature you location will experience

2.       Tender. A plant that will not tolerate the lows (or highs) in your areas.  a.k.a. Tropicals

3.       Half-Hardy.  Able to take your local weather-almost. Half-hardy or semi-hardy trees can take cold, just not as much as you may experience in your area. In Central Ohio, crepe myrtle, pomegranate and Schilling’s holly are in this group, able to take cold, just not the coldest temps we will get.

So the key to successful winter care-which means keep the tree alive for 5 months-is to make sure the environment is right. The biggest consideration is usually temperature.

From most difficult to easiest:

Tender plants-tropical cant take freezes of any kind, and usually have to stay above 50 degrees at minimum,. That means they are going into a warm environment, usually the one you occupy.  They remain active and growing (ideally) year round and will need daily attention. Light and humidity may need to be supplemented. This attention and effort means there is some work to do each day. 

The sort of grow room many of us dream about!
This is the set up Jerry Meilslik  has in Montana. His location is so far
north, and so far up a mountain he could have frost any day of the year.
He's proving the folks who say 'bonsai can't grow indoors" wrong 365!

Half hardy will take some cold, even down to light freezes, but should be kept above 32 degrees. Since they are dormant they won’t require daily care, but need to be prevented from drying out.  Likely areas for winter storage are unheated but sheltered spaces: enclosed porches, attached garages and the like. 

Fully hardy is the easiest. Why? It’s like a crock pot-set it and forget it. Tuck them in correctly and they will probably be alright come March. This comes from a combination of factors, mainly taking advantage of the plant’s natural ability to take care of itself. You just have to give it the right conditions to do it.

Like real estate, good winter care comes down to three things: location, location, location. Lets do a thought experiment: take two identical plants, and place one on the north side of your house, the other on the south.  Which plant will be more likely to have a constant temperature? If you said North, good guess. That plant snugged up against the house foundation, protected from wind and sun, will stay much more consistently cold over a winter. On the other hand the plant that is exposed to sun will be on a thermal roller  coaster, warm, perhaps even hot during the day, freezing at night.  That’s a recipe for disaster.

Many find a cold greenhouse a good way to store plants of
'questionable' hardness. These look like trident maples, which are hardy, but could use some
 pampering below 32 degrees. Some growers make sure the trees never get quite that cold. 

So the key is not to protect the plants from cold, but to assure that they stay reliably and consistently cold. So an enclosed porch on the north or east side of a building  will work well for half hardy trees. One with south or west exposure will probably get to warm.  Warmth promotes active growth and January in Ohio is not the time for a sleepy pomegranate to be waking up and pushing growth.

Follow the same principle when  scouting for a spot for the fully hardy trees. Look on the north side of you home first. Coal chutes, window wells and existing flower beds are handy places to winter over trees.  If that won’t work in your circumstances, the north side of a shed or fence can be utilized, and a curtain wall of burlap can make a summer time vegetable patch into a useful over wintering spot.

My feeling is that plants should be on the ground, with pots in contact with the soil. Mulch should be applied up and over the pot up to the first branch. This set up means the soil ball stays moist. When scouting a wintering location, look up-if the spot is under and overhang, rain and snow will not reach the trees and you will need to provide water. Really the easiest way to make sure over wintered trees stay hydrated is to shovel snow on to them.

When should trees go into winter quarters?  Each backyard will be slightly different. Once deciduous trees have dropped leaves, they are ‘asleep’. It’s easier to work if the ground is not frozen, so aiming for that part of the winter when it is cold but not frigid would be best, but its throwing the dice. (Helpful tip: if you are using bagged mulch, put it in the garage now so it is NOT frozen. Frozen mulch doesn’t spread well at all!) Waiting till it is reliably cold also means the little furry pests who would love to bunk under your bonsai pots and who would look at all the tree bark as useful food have found other accommodations.