A Greenhouse that Thinks it is a Mini Forest Garden

Maddy Harland
Wednesday, 19th June 2013

Maddy describes how she uses every available space to grow a variety of crops in a small greenhouse, making a weather-proof space as multi-functional and productive as possible.

With our increasingly unpredictable weather, it makes sense to make the most of your greenhouse. I used to use mine for growing seedlings started in a heated propagator, a crop of tomatoes and indoor cucumber in the summer, perhaps some oriental vegetables like mibuna and mizuma sown in early autumn for a winter crop if the tomatoes had finished. I also bring on potatoes in pots, hoping for waxy new potatoes at Christmas if hard frosts were avoided but at best my greenhouse was mainly busy in spring/summer with just two crops.

Now I ‘stack’ every vertical space possible to imitate a mini forest garden with a tree, shrub and herbaceous layer. Full size forest gardens can incorporate seven layers (see diagram) but it is amazing how productive a mini forest garden under glass can be with at least three layers.

This year, in my 10 x 6ft greenhouse, I am growing an espaliered peach on the back wall, my small tree layer (see main photograph). The peach is an own root stock variety. The stones were given to me by Achim Ecker at ZEGG ecovillage in Berlin and I have managed to germinate a few, another is in the forest garden. At ZEGG, near Berlin, there are hot summers and very cold winters and Achim's peaches thrive outdoors and are peach leaf curl resistant. My outdoor peach is not so happy in rainy England. The outdoor specimen is healthy and fairly vigorous, however, requiring a fairly hard prune every spring. We fertilise the flowers with a sable paintbrush and this year we have 41 peaches ripening. They grow large and juicy. Can't wait until August!

Mimicking the 'shrub' layer in the greenhouse

My ‘shrub’ layer consists of tomatoes, cucumbers, tomatillos (Physalis philadelphica). I grow cherry, plum and beefsteak tomatoes and favour traditional varieties of cucumber with spiky skins. They are crispy and taste delicious.

One herb cornerMy herbaceous layer consists of capsicums and herbs. I grow sweet pepper and chillis. I have also planted year-round perennial herbs like thyme, flat-leaf parsley and tarragon and add annual basil once the danger of frost has passed. The parsley starts growing in early spring and the thyme and tarragon thrive once the greenhouse heats up. I don't have to coat the glass either to prevent leaf burn in full summer. All the plants create enough shade to prevent burn but not too much to inhibit growth. The secret is not to overcrowd them. That said, every vertical available space is almost filled. I am thinking of growing strawberries and trailing tomatoes in hanging baskets from the roof next year.

Outside the greenhouse is guttering that harvests rainwater into a water butt. It is so useful to have a water source right by the door. Inside, I also use ‘Ollas’, a 4,000 year-old irrigation system originating in Africa. It comprises of 10 inch buried porous terracotta pots with plates for lids. The drainage holes are plugged with a wine cork and the pots are filled with water. As the surrounding area dries out, water is sucked through the terracotta into the soil. The roots of the plants wrap themselves around the pots. Evidence is that it is working. This system is a simple and cheap way to irrigate the greenhouse and can be used in any veggie bed. I hope it will prove especially useful when I am away on holiday for a few days.

I am always looking for other ways to stack layers and functions in my greenhouse but so far the idea of mimicking three layers of a mini forest garden is working well.

Maddy Harland co-founded and edits internationally acclaimed, Permaculture magazine – eath care, people care, future care


Further Resources

Forest Garden Favourite: Merton's Pride the juiciest of pears

Clay Pot Irrigation - a simple adaptation of an ancient technique

Video: A How-to Guide to Olla pots - and effective traditional irrigation system

Books by Maddy

The Biotime Log

Fertile Edges: Regenerating Land, Culture and Hope

Simon Benjamin |
Sat, 08/08/2015 - 13:39
I did something similar in my 13' by 30' Polytunnel. It has tomatoes. But also figs, passion fruit climbers. Flowers such as calendula, french marigolds, Verbena and peruvian lilies (for cut flowers) it also has runners beans climbing up. It also has herbs such as oregano that grows nicely in the heat. It has been Very full and i've had to "chop and drop" to make space to walk through and harvest but has been very productive, it is also likely that the soil is improving massively through all the tropical feeling growth. The amount of bees and hoverfly in it is amazing. Wish I could upload some pictures with this comment as its my little slice of heaven :)