Growing in a poly-tunnel or greenhouse/glasshouse

The Joy of having a Polythene Tunnel or Green-House – a polythene tunnel or a greenhouse is an expensive addition to an allotment.

If you are thinking of making this investment consider:

Ø  is the allotment your hobby, perhaps also for your partner and your family – how much more would you spend if your hobby was golf, horse-riding, collecting rare records or first edition books and comparatively how much more pleasure can your allotment give you?

Ø  are you planning to stay long enough to make the investment worthwhile? Of course, with a bit of effort you can remove your structure and re-position in your garden or give to a relation / friend.

Ø  it might seem to be stating the obvious but, it never rains inside your poly-tunnel or greenhouse – if you can’t be there regularly enough to provide the necessary water. Do think how you can arrange with someone to share this chore and the crops. Position your poly-tunnel close enough to your water supply to ensure you are not spending too much time and effort carrying water;

Ø  do buy the best you can afford – allotment sites can often be quite exposed and flimsy structures will not last a winter or even the next storm whatever the season! As my father always said ‘don’t send a wee lad on a man’s errand!’

Ø  this is an expensive growing space – do try to make it work for you all year round. The season can start early.

– by mid February you can plant Early Potatoes which can be harvested by May in time for transplanting tomatoes, or try a couple of rows of carrots which will be ready by May/June;

- seed beds for brassicas will have them ready for transplanting outdoors by April and in time for planting peppers, chillies, indoor cucumbers and aubergines;

- once the tomatoes, chillies and peppers, etc have been harvested you can plant a crop of spring cabbages which can over-winter and be ready for eating in March/April.

Ø  I see many greenhouses [though not so much in poly-tunnels where it can be difficult to set up] taken up with staging and shelving, allowing little space for growing. While some growers will enjoy this pottering space, for me, it is a waste of valuable growing room – consider what the value of the space is for you.

Ø  It is important to keep your indoor space clean – wash inside and out with an effective disinfecting solution [try Jeyes Fluid though, don’t allow it to soak the ground you will plant into] to remove moulds and algae which will build up and affect the light to your crops and the infections they can pick up.These algaes will also grow on the outside of the structure and will need removing.

Ø  After some years the soil will become sour and unproductive – especially if you’re growing the same group of crops each year, and will need to be replaced either by replacing the soil to a depth of 30cm [1 foot] or more or moving the structure to a new site. Of course, you can grow all plants in large containers which will avoid this problem. 

Moving the structure can be more than a chore- the poly cover would be destroyed if I moved  mine and the base 'poles' would have to be dug up from a 2 feet depth, in heavy clay soil. For me, it is not a consideration until my polythene cover has finished [now in place for five years]. I hope it will survive for another couple of years - of course, the longer the cover lasts, the more cost effective the crops you will grow. I must, for me, look to alternatives to moving the structure - even when replacing the cover becomes essential. Therefore, I must look at ways of supporting the soil within the tunnel.

Of course, if I had a larger tunnel - 25 metres, 50 metres, 100metres, it would not be a problem. Even better if I had 4 of them where I could rotate the crops. However, this is not the case. I do not have these facilities and must, like most of us 'cut my coat according to my cloth'. 

This is not sour grapes. I recognise that I am very lucky to have my poly-tunnel but, it is important to point out that many allotment sites have shared facilities within large or even huge indoor growing areas where members can have an area for growing and crop rotation is probably not a problem.

Do ask about this facility when joining an allotment association or similar site