There is probably a better name for this, which could be why I’m not having luck finding info on something that serves this purpose.
Long story short; we have a very short grow season which often means a single season is not enough to bring plants up to market size, even with a greenhouse buying me an extra month or so. I have been experimenting with growing plants in self pruning boxes (the bottom is a screen, root growth stops when it hits air, avoiding roots circling around) and barerooting them in the fall when they go dormant. I basically take a box with 25 or so currants/goji/you-name-it, bareroot them, and stash them in a single 2 gallon grow bag with dirt. The next problem is that our winters can be a bit harsh… We can see -30f but a more balmy -25f is more common.
Basically, I want to build a heavily insulated storage unit with a heating coil and a thermostat to store bareroots. Imagine something with a working dimension of around 6’ wide, 2’ deep, 3’ tall. Something like this but much shorter, top loader instead of doors on the front:
The 6’x2’x3’ would be more than adequate to support my plans for world domination; it is a one-man effort, I don’t want the effort to get too big. I can probably hit R-30 insulation. The idea is to run a heating coil and thermostat to keep the temperature from dipping bellow 0F, which is downright mellow for everything I would grow outdoors. Most winter kill happens from a combo of cold snaps and too fast of a temperature change.
In no particular order here is a list of questions I have:
Has anybody seen a project like this on the net? I don’t care to reinvent the wheel if somebody has already gone through the trouble to figure this out.
What temperature should I aim for? As stated I’m thinking just keeping it from going bellow 0F ought to keep them comfy, while still giving the plants enough stress to not forget what they need to put up with.
i imagine everything inside will still be buried in mulch/soft dirt/peat/woodchips to keep it moist and out of contact with direct air. What would be the ideal burial medium?
do I need to worry about ventilation? I imagine I would make it fairly air tight in order to keep it from loosing heat.
A bonus is that come late winter when I may want to access my rootstock, I can gently raise the temperature so I can soften the frozen mulch while giving the rootstock the signal that they need to start waking up.
I had similar project made for apple storage. This is what I had: 1) box - planks for frame, pink insulation panel for sides, and top and wooden bottom.
2) simple metal cover double outdoor light with lncandescent bulbs reconnected sequentially. This make them less hot and last longer.
3) very large cooler to sit inside the box. The box should be few inches longer and wider than the cooler. The height of the box has to be enough to accommodate height of the light plus cooler plus 10 inches. Lights go on the bottom of the box, cooler on top, raised on bricks. It should be about 5 inches between bottom of the cooler and lights. Small fan on the bottom will help too. And a thermostat. I kept it in the shed, but our winters are mild, if you bury it in the ground and use boards to protect the top from the snow caving in, you could have enough protection. Pile of wood chips on top coul help too.
Root cellars take a lot of creativity and A/C here. A fellow a few towns over dug a big trench . Then drug a school bus they sprayed with marine paint into it. Pretty neat you can enter from both doors. Which they built an insulated doorway in. They filled dirt under the frame and sides. And fixed a pond liner over the roof top.
For the size of the project I’m leaning towards building something that looks better than an outdoor chest freezer, and better insulated to boot. a 6" structural insulated panel could hit just north or R30, which would make it incredibly cheap to regulate the temperature up, and to keep the temperature down when ambient air gets warmer.
Not to mention that anything frozen outside is usually frozen for the duration; with this I could crank up the thermostat to have access to my bareroots earlier, specially handy when I get my greenhouse going.
I’m still trying to find out if there is a need for ventilation and how low a temperature I can keep it. The lower the less expensive it is to run (I’m spending energy heating, not cooling) but also I do want to adequately stress the plant material.
I built this last year for my wife’s chickens. Its a chicken coop of course, but easy enough to morph into what your looking for. It’s 8x16 - 128 sqft. 8 foot tall in the front, 7 foot tall in the back. I had no plans just a picture that my wife put in my head and my sawmill and a bunch of southern yellow pine logs. The deck and plywood is storebought ground contact pressure treated southern yellow pine for longevity.
I’m a good builder of stuff. Mostly I’m trying to figure out the technical aspects of bareroot storage (temperature, humidity, ventilation, etc. etc. etc.). I may end up having to dig into the scientific literature which I’m sure leans towards large operations but optimal parameters should not change.
I’ve actually thought about something similar here for my potted plants – primarily bench grafts waiting to go outside until next spring as well as potted figs and hybrid persimmons. I snagged about 80 of 4’ 2x6 pressure treated cutoffs for $40 a couple months back so I’m basically thinking something like a 4’ length x 8’ width x 4’ height box framed with studs and insulation. Ideally it would be something I could disassemble and store or repurpose for summer.
So not entirely the same thing, but I figure this is as good a place as any to bookmark and discuss build plans/ideas for this type of project.
I’m having a hard time just finding good data on the ideal temperature for storage. Some seem to peg it at 32F but honestly that’s T-shit weather here; frost line is around 4’~6’ feet deep, no amount of snow or leaves will keep anything on the ground insulated enough not to freeze solid.
I don’t have an answer for what is ideal for survival, but when I have tried overwintering perennial plants inside a greenhouse they all died. When I throw them in a hole in the ground outside, leave them in a bucket in the yard, or leave them in a planter box on the deck, they live. I always thought maybe it is the snow providing a layer of protection and insulation, and water as it melts. The greenhouse plants look extremely dry (and dead) come spring.
Basically there is a number of parameters that can be manipulated in order to optimize survivability and best state for growth. Temperature, humidity, exposed bare roots, roots covered, whole plants covered, and then what different plant families like may vary.
I’m hopping that I can find studies covering this subject.
I grew up in a part of MN where we’d have the occassionally winter with balmy -30 degrees, often a week or more where the high temps for the day were maybe a tropical -20. Nurseries wintered stock by making a big pile, laid down on the side, and stacked the pots. Covered that pile with something, put down a healthy layer of straw or hay as mulch, then covered it all again with another sheet. The outside sheet was usually plastic, the inside sheet was often plastic, but really, the purpose of that sheet was to keep the straw/mulch layer away from the branches, so anything worked…but plastic is generally simple to obtain.
bareroot storage isn’t actually frozen. It’s more of a cooler, lower than 40 degrees F and high relative humidity. the idea is to keep the bare root plants from actually freezing, and to keep them from drying out. Water is generally more misting, less spinkler or hose.
How you handle stock is a bit different, so some tweaking is to be expected.
I may suggest you consider building larger than you think you need. two reasons: I’ve never heard anyone lament about building too large, always building too small, and managing the environmental controls is often a bit easier with larger buildings. Stability is easier to obtain with fewer swings from high to low.
I currently live in southern new england, where the extremes of winter are pretty much non existent, but people are always looking to start early and go late. High tunnels have come into wide use to extend the season for a number of crops on both ends of summer.
What’s your weather like as the seasons change? Lots of sun? Lots of clouds?
