Polytunnel Vision

Last Saturday I was very lucky to have secured a place on a Growing in Polytunnels course with none other than the God of growing stuff, Klaus Laitenberger (he is often on Garraí Glas with the lovely Síle Nic Chonaonaigh).

Klaus moved to Ireland in 1999 when organic vegetable growing was starting to become fashionable again. It took Klaus a few years to adjust to the growing climate here and having spent the day with him, I think he’s pretty much mastered it. Klaus grows organically, doesn’t use sprays or chemicals and has hardly a slug in his garden. Impressive, and it wasn’t even 10.30am.

The course was held in the Nano Nagle Centre near Kilavullen. There’s a whole heap of history behind this place which would be a whole other blog post. Now they focus on heritage, spirituality and ecology. They hold retreats, yoga and meditation classes, farm walks, crafting classes and conferences. Actually there isn’t a whole lot they don’t do. Their organic farm is run on 34 acres and comprises of 100 chickens, 2 donkeys, 2 pigs, ducks (for slug patrol) and some lambs. All of these animals give back to the farm. The pigs dig and are kept for meat, the donkeys graze and produce manure, the chickens produce eggs for eating and selling, meat and manure, the ducks provide eggs and are on slug patrol and the lambs provide meat. The whole farm is self sufficient and everything has a purpose.


We started off the course in a classroom setting, notebook and pen in hand and I wrote, I wrote everything I could.

In the Klausroom

We started out talking about organic certifications, what organic is and isn’t and bio-dynamics.

I had heard of bio-dynamics before but I wasn’t quite too sure what it was. It was founded in 1924 by spiritual scientist called Rudolf Steiner. It is a holistic method of organic farming that works with the development and interrelationships of the soil, plants and animals as a self sustaining system. It uses manures and composts instead of artificial chemicals, integrating farm animals, crop cultivation and care of the land and the use of fermented herbal and mineral mixtures to add to compost or sprayed on the land.

One example of a bio-dynamic preparation is as follows: Take one cow (not bull) horn, stuff fresh cow manure in the horn, bury it, leave until spring, dig out the cow horn and take a handful of the manure and put it into the a barrell of water. Starting on the outside, stir for one hour and create a votex, after an hour reverse the direction and stir for another hour. This is believed to inscribe memory on the preparation. The preparation is then sprayed onto the land.

You might think it sounds a little ‘hippy-ish’ but from what I have read online, people seem to get good results. If I could get my hands on a cow horn, I would happily give this a go. There are some other preparations I might try but I will have to wait until next year.

Sweetcorn in one of the polytunnels

After this we discussed why we want to grow our own and why organically

  • Fun
  • Cheaper
  • Taste
  • Satisfaction
  • Environmental reasons

Next up was the advantages and disadvantages of glasshouses verses polytunnel

  • Glass houses are a lot prettier but 10 times more expensive
  • Polytunnels are cheap, you can make your money back within a year or two from the produce you grow (and don’t buy)

Growing in Polytunnels/Glasshouses have many advantages

  • Extends the growing season – sow early potatoes in January, early varieties of carrots and beetroot in February and plants like courgettes will fruit for more than twice the time than they would outside
  • Plants that wouldn’t normally be grown in this climate can be grown inside a polytunnel – tomatoes, basil, peppers, aubergine etc
  • Propogation – starting seeds off in the right environment
  • Grow salads in the winter months – Rocket, Mizuna etc

Maintenance of the tunnel

Ventilation in a polytunnel is very important as this prevents diseases. Contrary to what you might think, you do not have to water every day in a polytunnel and when you do water, always in the morning.


  • Feb – March – Once a week
  • April – June – Twice a week
  • July – August – 3 times a week
  • Sept – Oct – Twice a week
  • Nov – Jan – Once a week

We have a misconception in Ireland that we need to water plants everyday. We don’t, far from it. Too much water gives shallow root systems as the roots don’t have to look very far for water. A deeper root system gives the plants a better chance of surviving. Klaus said that since he has lived here he has watered outside on only two occasions. And leaf burn from watering when the sun is shining doesn’t happen, maybe in California but not here.

We discussed irrigation systems inside a polytunnel such as sprinkler systems, drip systems or porous hoses. Klaus basically summed up that you can’t beat a watering can, you know exactly where you’re going with it. Some plants, like cucumbers, like to be misted so I imagine a hose in the polytunnel would be a good plan. Heating mats with a thermostat for seedling germination are an excellent investment and are very cheap to run.

Irrigation System – drip hoses

We learned about the different types of polytunnels and how they are are constructed – either by burying the plastic which makes it difficult to tension or using crop bars (metal bars) to hold the plastic in place. Climbing bars and crop bars are important and two doors are better than one to allow for full ventilation. If the polytunnel is long enough, middle ventilation would be required. Sometimes rainwater gutters can be attached for collecting rainfall.

Tomatoes in the polytunnel

At this point we were in the polytunnel so naturally we talked about the crops. What to grow in the polytunnel, where, how, diseases and pests, prevention of said diseases and pests. Klaus sampled a green chilli and asked if anyone else would like a bite, for some reason my hand shot up and I have no idea why, I don’t do hot or spicy foods. Needless to say, this one was extremely hot and it made my eyes water and my mouth was on fire for ages so I ate a freshly picked tomato! Klaus talked about using garlic a lot in prevention of pests. He makes up a solution of garlic spray and sprays regularly on his plants. The theory being that the nematodes don’t like the taste of it so don’t hang about for too long. He asked for a volunteer, again that hand of mine shot up (which is very unlike me as I’m usually quite shy and hide behind tall people). So the task this time was to prove if garlic is absorbed by the body. And to do this I had to walk around with a clove of garlic in my flip flop for the day and to see if a garlic smell would come out in my breath.

Obviously, we wanted to know Klaus’ secrets on weeding and these are the three golden rules he lives by.

  • Only hoe when dry and hand weed when wet
  • Only hand weed where the hoe can’t reach
  • Hoe regularly and when the weeds are small

The best investment any gardener can make is spending about €35 on an oscillating garden hoe, much better than your dutch hoe.

Another organic weeding technique to use is the false/stale seedbed method. Prepare your seedbed as if ready for planting. This preparation means that any weed seeds have been brought to the surface and will germinate. When the weeds are an inch or two high, hoe or rake them. Repeat this again if more weeds show. The idea being once the seeds have germinated and hoed off they will die and compost in the seed bed giving some nutrition back to the soil. Of course you could always dig your vegetable patch at night, that way the seeds won’t have any light togerminate.

After lunch (and I was still walking around with the garlic in my flipflop) we were back inside and talking about seeds – Open pollination, F1 Seeds, Treated Seeds, GM seeds and Organic seeds. We discussed Ireland’s decision to allow GM potato trials in Carlow.

To harvest tomato seeds

Chose an overripe tomato from the best plant (positive selection). Cut it open and squeeze into a glass with a bit of water. Leave it for 24 hours and then sieve . Clean the seeds under a running tap. You can either put them on kitchen paper 2cm apart or on a saucer in the hot press for about a week and then store in seed envelopes. The advantage to the kitchen paper is that when it comes to planting, you place the kitchen paper on top of a seed tray full of soil. Layer 1cm of soil on top and water and they are all ready to germinate.

Crop Rotation was next on the list to talk about. Crop rotation is extremely important as some crops are greedy and there will be a nutrient depletion in the soil, meaning that if you planted the same crop in the same place next year, it wouldn’t do well. Crop rotation also prevents the spread of soil born pests and diseases. The most important crops to rotate are from the Brasica family – broccoli, cabbage, kale, sprouts, mustards, rocket, mizuna, raddish, turnips and swedes and the allium family – onion, leeks and chives. If potatoes are not rotated when they are outside they are at risk from eel worms.


After we had a look at the outside vegetable patches full of linseed, varities of artichokes, comfrey, beetroot, cabbages and so much more. We were taken on a tour of the farm by the Farm Manager, Noreen to see the chickens, pigs, donkeys and vegetable patch which was over grown and unfortunately full of blight. It was this point I asked do they take on volunteers and Noreen said yes! I did try and volunteer and Fota Gardens but unfortunately they never came back to me. The Nano Nagle Centre is closer to me and the animals and organic gardens are much more enticing to me as I secretly pine for a small holding of my own.

Outside vegetable patch


If you ever get to go on any kind of course with Klaus, I would highly recommend it. He is a fountain of information and great fun. I could have talked and listened to him all day. Over all it was an incredibly inspiring day and I cannot wait to start volunteering at the Nano Nagle Centre.



3 responses to “Polytunnel Vision

  1. Would love to visit there! Lucky you getting to volunteer. (Fota’s BIG loss)
    Love the idea of harvesting the tomato seeds. Do you keep them until next year? and would love to know more about the use of garlic!
    Great post, as always. Yjank you


  2. Cant beleave you learned so much in one day,i spent 2 days a week for 9 months last year in organic horticulture course and didnt learn much more than you did.


  3. Cant beleave how i spent 2 days a week for 8 months last year learning about organic horticulture and you learned so much in one day,amazing !


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