Greenhouse Forest garden - four years later

Spring 2014 we traveled a 130 sqm greenhouse in Putt Forest Garden Ant. With so much space at our disposal, I could not help to build a small woodland garden of just under 40 square meters of greenhouse southern part. The greenhouse is a so-called polytunnel, with a single layer of greenhouse plastic, something that I think has been quite important for plant growth. the greenhouse is 8 m brett, 16 m and has a ridge height 4,5 m. It is the heaviest clay soil we have and we have jordförbättrat with manure and other organic material to improve farming conditions. The entire glasshouse is connected to our drip irrigation system. Now, four years after the planting of the first trees and bushes it is possible to draw some initial conclusions that I want to share with you in this post.

Zonknäckning with unexpected result

The idea of ​​the greenhouse forest garden was to improve our cultivation zone with a couple of cultivation zones, so that we could grow things that can be grown in cultivation zone II or III. The result was, however, a climate that does not exist in Sweden, with large fluctuations between day- night temperatures and summer, very low humidity and still really cold winters, Thus, like in Central Asia, Himalayas and parts of the US where there is a distinctly continental climate.

Since the receiver to our climate station is in the greenhouse, I have an almost three-year time series of climate inside and outside the greenhouse. The average (!) the difference between day and night temperatures from March to October 2017 low example 26 degrees inside the greenhouse, while out in the open was as little as 9,5 grader (So far this year, the figures 23 degrees inside and 14 degrees outside). Kontinentaliteten (the sum of the temperature difference between July and January and between day and night during June) Located in the greenhouse at 50-60, compared with 30-35 outside. So distinctly continental climate is on no place in Sweden.

Between March and October 2017 was air humidity average 11 percentage points lower than out (the difference in the year so far). Even in winter, the temperature difference between inside and outside pretty big. As was the coldest -18,1 degrees in the greenhouse, when there was -25,8 grader (the 6 January 2017).

These climatic conditions, I did not really became aware of until a year or so ago, meant that some plants were significantly better than others.

Plants that thrive in the continental climate

Already the first year I planted asimina (Asimina triloba), hybridcitrusen ’Dunstan’ (Citrus x aurantinum) and hardy kiwi (Actinidia arguta), which I thought would storm thrive in the greenhouse. The year after the advent Chinese Cornus florida (Cornus kousa var. chinensis), 3 st Chinese toon (Toona) and U.S. pepper tree (Zanthoxylum americanum). The US pepper tree and Toon-trees freezes every winter, and otherwise it is only a female plant of hardy kiwi that has survived, which is not surprising considering that all these plants naturally thrive in lövskogars half shady, moist undergrowth.

The plants that have fared best are apricot (Prunus armeniaca), mullbär (Morus sp.), and grape (Vitis x spp.) all seem to thrive well in the tough inland climate. Mulberry variety 'Illinois Everbearing' now provides fruit for the third year and we have expanded the cultivation of the Swedish variety 'Mullet' also. Apricot cultivar 'Hargrand' bears its first fruits now and we can now confirm that it is not self-fertile. Of the hundreds of flowers produced was despite persistent hand pollination only two fruits. Therefore, it has been joined by two seed grown apricots from the Baltic provenances. Although peach (Prunus persica) we planted last year wintered well in the greenhouse, but is now infested with spider mites, which probably has the low humidity making. If the problem persists, the next year it may move out in the open instead. Finally, we have a prickly plant of variety 'precoce the Dalmatie' (= 'Bornholm') in the greenhouse, which has so far frozen back 80-100% every winter. This year, however, it has grown more than ever, so perhaps standing still for a while.

Two plants that are on the way into the greenhouse is persikomandel (Prunus x persicoides) and wolfberry (Lycium barbarum), that seems completely hopeless to get the crop from here in the open, even though the plant is fully hardy.

Örtskiktet

What has been the biggest challenge is örtskiktet in greenhouse timber garden. We have tested all sorts of perennials, but most seem to emphasize with during the March huge temperature swings, with the summer heat in the daytime and sometimes severe frosts at night. We've tried:

• Potatisböna (American apios)
• Strandbeta (Beta vulgaris ssp. maritima)
• ’Helgoländer Wildkohl’ (Brassica oleracea ssp. oleracea)
• Cikoria 'Red Grumolo' (Cichorium intybus var. foliosum)
• Japanese ginger (Zingiber mioga)

all of which are a little hesitant in the open with us in terms of hardiness.

All that is left of all the experiments are strawberries, but even there, usually half of the plants die during the winter and there will never be any good ground cover them. There I was thinking test is a little different bulbs from areas with continental climate, but much more than that, I can not really think of, so I welcome your suggestions for more (multi) edible plants. Otherwise, we might just fill the space between the trees and bushes with annual crops in the rest of the greenhouse, planted out when the temperature fluctuations decreases slightly and the humidity increases ahead mid-June.

Sorken

You can not write a post on this blog without mentioning vole. Although it thrives in the greenhouse tough climate (albeit a little less than out in plantations) and this winter caused you some concern. To my chagrin took seven of eight grapevine. Luckily left it my favorite kind left, ’Somerset Seedless’, which is now crowded with clusters. The other varieties I had time to take cuttings or layering on and now they are planted in the vole secure cages, but sadly it is still losing a few years of growth.

improvement opportunities

The attempt to crack zones had thus not quite the desired outcome, but now that I know what plants work well, it will be fine anyway, although I still miss the forest garden feel with their various layers and exuberance. If you want to get into a zone or two for real and not end up in another continent, I think we need to focus on another type of greenhouse that reduces fluctuations in temperature between day and night, and increases winter's lowest temperature. A glass house built against a brick wall could be a variant. Another that I go and dream about is a real greenhouse in corrugated plastic with good insulation value. Where it should be possible to create a lush woodland garden without any additional heat. Do you have experience creating timber gardens in the greenhouse environment? Please share here or the Facebook group Forest Garden Growers!