Winter to Spring and Back in 24 Hours ...

     ... over, and over, and over again. So it has been for much of the last several weeks. Days with highs above freezing followed by nights with lows below freezing, one after another, are almost starting to feel like "the new normal!"

This weather pattern has been playing merry hob with my temperate-zone trees' spring responses. My American larch is typical, I think: Normally, from first green to full bud burst takes about a week, in my observation. But the first green - bud break - appeared several weeks ago, and as yet none of the buds have opened enough for individual needles to be distinguishable! I can't help but be concerned that this abnormally extended pattern of freeze-and-thaw will do some injury to new and still-tender foliage.

In an effort to buffer conditions for my cold-hardy trees, I decided to put up a small inexpensive greenhouse to hold them until temperatures are no longer doing their winter-to-spring-to-winter dance. My wife came across this product on-line; it measures 7 feet by 10 feet (a shade over 2 meters by an even smaller shade over 3), assembles in a couple of hours, and costs less than $80 US. I plan to keep it to use in future years as a temporary spring shelter for newly-repotted trees. 

Temporary plastic greenhouse to moderate temperatures for temperate-zone trees.

We recently moved, and our new location is windier than I expected. The tie-down equipment that came with this greenhouse is as inexpensive as the rest of it - OK, it's cheap. And a little story Ryan Neil told in a Mirai Live stream some weeks ago wouldn't leave my mind.

Every spring, Ryan and Masahiko Kimura's other apprentices would put up a temporary greenhouse on the premises. Part of the process was to tie it down with lots of heavy ropes. The first time Ryan Neil was involved in wrestling with the ropes, he turned to another apprentice after a while and asked, "Why are we doing this?" The answer went something like this:

"Well, ten years ago, this greenhouse took off. It was a windy day, and the whole thing lifted off the ground, sailed the length of Kimura's property - high enough to miss the bonsai there - and took out that second-story window on the far side of the street." (End of questions.)

Rather than provide a mini-sequel to Ryan Neil's story, I decided to add my own tie-downs to what came with my little greenhouse. My anchors are dog-tethering stakes - the kind with a business end like a spiral auger - and I used 3/16" nylon twine (almost 6 mm). My measures seem to be adequate: the wind picked up this afternoon while I was moving the trees into the interior, and while the plastic cover flexed and snapped and the tubular frame flexed slightly, everything stayed in place.

A closer view of the tie-downs. I decided on the Lilliputian approach: more thin ties instead of fewer thick ones.
(Think of Lemuel Gulliver immobilized on the beach by dozens of thread-fine ropes.)

The greenhouse is unheated. The trees' containers are resting on a single layer of landscape fabric on top of the soil, so get a bit of heat seeping up from the earth. The greenhouse itself will block the wind, and will reduce heat loss at nite by a few degrees, I expect. I put a min-max thermometer inside so I can monitor the temperatures.

Here are the trees inside, ready for the door to be rolled down and zipped shut for the nite.

The greenhouse holds all my hardy trees, with the exception of my largest, a Thuja occidentalis, a.k.a. American arborvita.
It's as cold-hardy as a musk ox, tho, so I could safely leave it outside on the sheltered side of the greenhouse.

:-)  :-)  :-)