If you get caught off guard by a quick freeze and do not have enough time to get your plants to their winter quarters or only need protection for a day or two, simply lower bonsai under there summer stands and if needed drape plastic or a tarp over the stand.Â
Conifers
I store my conifers in two different locations. Trees that are in development are in my garden in a layer of mulch. A building blocks the wind from the north, and I planted asparagus to act as a wind block from the west. I leave the asparagus stocks up until spring and then cut them down when I want my bonsai to get additional sunlight in the evening.
My more valuable trees are in a location that has buildings blocking the wind from the west and north. These trees are on the bed of gravel I use for my summer bonsai bench. The bench itself is made from cinder blocks and 2x10s. I leave the stack of cinder blocks in place and move the 2x10s in front of the cinder blocks to block wind from this direction. Then I put down landscaping fabric or an old bed sheet, place my bonsai pots on top of that, and fill in the gaps with gravel or wood chips. The bed of gravel helps with drainage.
Because I live in an area that can get soggy in the spring or during a thaw, I have had problems with junipers that were dug into the ground getting too much water.
Deciduous and less cold tolerant trees
My deciduous and less cold-tolerant trees go into an unheated barn to get out of the wind. For these, I place pink foam insulation down. Plants are then placed in plastic crates with one inch of rubber mulch on the bottom for insulation and drainage. I have also found that insects and mice do not seem to like the smell of the rubber. Once I have placed as many plants as possible in the crates without any touching the sides, I fill in the gaps with rubber mulch to the top of the tallest plant in the crate. Then, I simply stack the crates next to each other. If things get very cold, I have some old lambing pens that I enclose the collection in and cover with a plastic tarp. A 75-watt bulb will usually keep things around freezing on cold nights. I picked up a thermal cube from Fleet Farm that turns on at 20 degrees to make sure things do not get too warm or waste electricity.
Jason Davids
