Polytunnels and greenhouses are a boon to vegetable growers but it takes expertise to get the best use out of them, writes FIONNUALA FALLON
PRUNING SOME APPLE trees during a recent sunny day, it struck me that it’s now, during the dying weeks of this Irish winter, that the country’s vegetable gardeners have it particularly tough. Our hearts insist on telling us that spring has finally sprung and that it’s time to get outdoors and busy ourselves in a frenzy of sowing, hoeing and growing. Our heads, meanwhile, firmly say otherwise, conscious that other than a few hardy exceptions, we’d be better off holding back just a little longer.
Our heads, of course, are right; Ireland may be enjoying what remains of a record-breakingly mild, almost frost-free winter, but the icy weather that our European neighbours recently endured has served as a timely reminder to impatient gardeners everywhere. Spring may be tantalisingly close, Mother Nature has frostily informed us, but it isn’t quite here yet.
Unless, that is, you are one of a growing band of gardeners lucky enough to have the use of a glasshouse or a polytunnel, in which case the seasons march to a very different clock. Because of their relative affordability and the comparative ease with which they can be erected, tunnels in particular have revolutionised the world of the Irish home grower in recent years.
Admittedly, your average polytunnel doesn’t look the loveliest, but even on a winter’s day, the temperature in these giant steel-and-polythene structures will be an average of six degrees higher than outdoors. In summertime, meanwhile, the temperature can easily reach the sultry late 30s, encouraging the nation’s sun-lovers to indulge in a spot of impromptu sunbathing.
Vitamin D production aside, the result of this wonderful man-made microclimate is that it allows gardeners to grow a surprisingly wide variety of food all-year-round as well as a range of tender crops that would otherwise sulk in our Irish summers.
Many fruit and vegetables traditionally grown outdoors will also crop much earlier/for longer under plastic. Thus the country’s polytunnel gardeners can be harvesting Florence fennel, beetroot and lettuce in January, strawberries and early potatoes in April, courgettes, cucumbers, tomatoes and French beans in June, while leafy crops like oriental salad leaves can be harvested through late autumn into winter.
The catch (there’s always a catch) is that to do this successfully requires organisation, forward-planning, and a good degree of expertise. Help for struggling Irish gardeners first arrived last year, in the form of the Cork-based writer Joyce Russell’s excellent The Polytunnel Book. That’s now been joined by the brilliant Vegetables For the Polytunnel and Greenhouse, the latest book by the Leitrim-based gardener, Klaus Laitenberger, of Milkwood Farm.
Taking up where his first book Vegetables for An Irish Garden left off, this follows a similar format in terms of its wonderfully clear and concise style as well as in its size, design, layout and illustrations (the lovely pen-and-ink drawings from Thomas Etty, for example, are a distinctive feature of both of his books).
Along with almost 60 separate entries on the cultivation of individual crops, where Laitenberger covers everything from American groundnut to yacon, there are also useful chapters on site selection, soil fertility, pest and disease control, propagation, crop rotation and greenhouse/polytunnel management as well as a month-by-month guide, a vegetable crop summary in handy chart format and a glossary of common gardening terms.
As a highly-qualified, professional gardener who once ran his own successful organic market garden in the UK, Laitenberger writes with a lifetime’s worth of hard-earned experience and knowledge under his belt. Yet what I like so very much about both of his books is that he never finger-wags or rigidly lays down the law, instead gently encouraging his readers to experiment for themselves in terms of the techniques or the varieties that will work best for them.
That said, Vegetables for the Polytunnel and Greenhouse is jam-packed with useful information and eminently practical advice, with tips on everything from how to harvest basil to choosing the most bolt-resistant carrot varieties, or maintaining soil fertility. Also included are a series of useful charts giving optimum temperatures and recommended sowing methods for successful germination of the different vegetables as well as sample planting plans based on a four-year rotation cycle. Just as in his first book, Laitenberger is also brilliant when it comes to the important questions of how much and how many, as well as how to cleverly maximise the use of space.
Seasoned gardeners will also find much to interest them, such as the fact that celery grown in a polytunnel or glasshouse is generally far superior to that grown outdoors, that the leaves of the sugar substitute Stevia rebaudiana (a tender plant well suited to polytunnel cultivation) are 10 times sweeter than sugar, or that the tuberous yacon is a close relative of the dahlia (the scatologically-minded might also be amused by the fact that its leaves were used by the Incas as toilet paper).
His wonderfully informative book aside, he also gives one-day courses on growing in polytunnels/greenhouses at his home in Tawley, Co Leitrim, in the magnificently spacious wooden glasshouse he built some years ago with the help of three travelling German journeymen. As befits a professional gardener of his standing, he and his wife Joanna even held their wedding party in it. “Unfortunately”, Laitenberger writes wryly in his book, “a few tomato plants had to give way for the occasion.”
Vegetables For The Polytunnel and Greenhouse is available by mail order from milkwoodfarm.comfor €14.95 plus €3.50 pp. A list of stockists is also given on the website
DIARY DATE
Bellefield Plant Fair will be held on March 3rd (11am-4.30pm), at Bellefield House, Shinrone, Co Offaly. Entrance fee, €5. See angelajupe.ie for details
This week in the garden
Prune roses (bush and repeat-flowering types)
Where lawns aren't water-logged or frozen, give them a light trim
Sow seed (indoors, in a heated propagator) of tomatoes, chillies, aubergines, celeriac
Sow seed (into modules/trays, in gentle heat and under cover) of onions, lettuce, some brassicas, and bedding plants such as petunias, dahlias, lobelia, nicotiana
