a mediateam website

See a sample issue of The Irish Garden!

Ask Gerry

  1 - 6 of 8 answer(s)

tunnel heating

i have a plug in electric radiator(which is in good condition but an old style) would you think that this could be used when and if neccessary in my two bay hobby tunnel. ANGIE, ROUNDWOOD, Co Wicklow Posted: 13/12/2011


A heater of this size is likely to be too small for a two-bay hobby tunnel. It would suit an 8 x 12 feet greenhouse, but might address relatively minor levels of freezing weather in a somewhat bigger space.

There is an issue about the suitability of a heater designed for indoor use in a polytunnel as it may not be adequately insulated for a damp environment. It would be wise to consult with a qualified electrician about the heater and its installation.

At the very least a suitable RCD circuit-breaker should be fitted to protect against electric shock.



l am in the process of building my base for my new green house 6 foot x 10 foot. l have read in a book that a good ldea is to put sheets of styrofoam around the outside frame of the greenhouse 2 foot deep to keep the cold soil coming into the soil in the greenhouse. Is this safe to do? can or would any chemicals leach from the styrofoam. Carrotman, Drumcondra, Co Dublin Posted: 13/10/2011


The principle is the same as putting insulation into the concrete flowers of a house but there is no significant advantage to this.

A greenhouse needs to be freely drained and water movement in the soil levels out temperatures very quickly.

Also at that depth the soil temperature does not change all that much year-round, it is the top 30cm that heats up.



I have a polytunnell 25' x 14' approx with one entrance door. Plants tend to wilt from the heat on warm days even though the door is left open. Do I need a second opening at the opposite end of the polytunnell for air to circulate or can I do anything else to remedy this problem. Plants are watered every evening after sun down. marksarah, portlaoise, Co Laois Posted: 03/05/2011


A poythene tunnel can be very warm if it depends on ventilation by one door on hot days. Ideally, it should have a door at each end. But a 25 foot house is quite short and one door should suffice, if it is big enough.

If the polythene is held by a rail at soil level, as some are, the soil can be dug out under the rail to allow air in along the length of the tunnel. Some tunnels have the polythene buried along the sides to hold it down and it is not possible to dig out these.

Plants should be grown in the open soil of a polytunnel and are much less likely to wilt, especially if adequate amounts of moisture-retaining humus are applied.

Shading material is a possibility, ideally placed on the outside of a greenhouse but this can be hard to do.





protection from frost

I have a tunnel and i want to protect my geraniums and fuchias,is covering them with fleece enough at night? And do i remove it during the day? itahannon, listowel, Co Kerry Posted: 26/11/2010


Fleece might be enough for a light frost, perhaps not enough for a heavier one. Raise the plants off the floor if possible and cover with more fleece, old blankets etc or use a frost protection heater.

Fleece can be left on for a few days as light gets through it. Heavier covers must be taken off. 


keeping greenhouse plants from freezing

weather forecast is dire for the weekend. ive got a 8X6 unheated greenhouse. its full of scented pelagoniums, chillies, mysotidiums, etc. all fairly fragile. would you recommend lighting a few candles in the evenings to heat it? (no electricity available). alternatively i could bring everything indoors but as ive about 60 pots.........id rather not. 080720101, bray, Co Wicklow Posted: 23/11/2010


In Bray, the temperatures are unlikely to drop to very severe levels.

Candles cannot deliver enough heat  .... a greenhouse of that size would need a heater delivering at least 1kilowatt, that is the equivalent of a one-bar electric fire.

A frost protection heater can be useful, and there are paraffin models if you cannot use electricity. These will protect tender plants on cold nights in winter, but the temperature has to drop below zero for damge to be caused.

You could also cover tender plants with old blankets or duvets, taking them off by day. 



Solar pump.

Will a solar pump work inside a polytunnel? brigette, Arigna, Co Roscommon Posted: 09/04/2010


A solar-powered pump works on sunlight which it can get in a tunnel.


Garden.ie Members

Not a member yet?
Join now to:

Join Now

Existing Members

Forgotten password

Garden.ie CLUB

Join Ireland's first online garden club! Share pictures of your garden, make new friends and chat with other gardeners. It's simple to join and free! Register Here

Featured Members

Ask Gerry

Gerry DalyTry our unique advice service from editor Gerry Daly. Got a question right now? Search here to see if it has been answered already:

a mediateam website

©2018 Garden.ie. Mediateam Ltd, Media House, South County Business Park, Leopardstown, Dublin 18.

Tel (+353 1) 2947777 Email info@garden.ie

Website Design by KCO.ie