Allotment Gardening Advice Help Chat

Growing => Growing in Greenhouses & Polytunnels => Topic started by: Handy Andi on May 11, 2013, 18:00

Title: Greenhouse temperature
Post by: Handy Andi on May 11, 2013, 18:00
Hi all,

We have an unheated glass greenhouse, 10' by 8', at the allotment. I'm really running out of space in the house and need to put many of my plants, including beans, tomatoes and cucumbers in the greenhouse, but I'm worried that it's get too cold for them at night.

Does anyone know what the approx difference is in temperatures inside and outside a glass greenhouse? For instance, if it's 5 degrees outside, what will it be inside? I can't get down to the plot at night and so have no idea how cold the greenhouse would become.

Many thanks

Andi
Title: Re: Greenhouse temperature
Post by: DD. on May 11, 2013, 18:03
A unheated greenhouse will retain it's heat, but only for so long. As everything inside it cools down, it will drift down towards ambient temperature. The best you could hope for is a couple of degrees above what it is outside.
Title: Re: Greenhouse temperature
Post by: mumofstig on May 11, 2013, 18:11
That's why I recommend getting a max/min thermometer - so you can see what's going on ;)
They're cheap enough
 on ebay (http://www.ebay.co.uk/itm/Solar-Digital-LCD-Suction-Window-Greenhouse-Thermometer-/230872566064?pt=LH_DefaultDomain_3&hash=item35c113c930#ht_3487wt_958)
Title: Re: Greenhouse temperature
Post by: mjpalin on May 11, 2013, 18:12
We've inherited a greenhouse (if you can call it that, homemade, no glass, but the double wall poly stuff instead), this past week we've seen overnight temps as high as 11 and as low as 5, so nothing that needs constant 10 or above in ours yet. Hoping, hoping that it won't be too much longer as like you running out of space indoors.
Title: Re: Greenhouse temperature
Post by: Steveharford on May 11, 2013, 18:12
Apart from a heated propogator to start things off. Everything I have:, tomatoes, peppers, sweet corn, beans etc have been in my unheated little poly tunnel for a couple of months. When the frosts were bad I just put some fleece or anything I could find, over them, and I haven't suffered any setbacks whatsoever. At times the night temps in there dropped to just above freezing. Maybe they are already hardened off but it all looks really healthy.
Title: Re: Greenhouse temperature
Post by: mumofstig on May 11, 2013, 18:15
Steve it would really help if we knew where you were when you say things like that  :nowink: - please add a location to your profile.
Title: Re: Greenhouse temperature
Post by: Handy Andi on May 11, 2013, 18:40
Thanks for all your replies  :) I do have a thermometer in the greenhouse, but as I'm unable to get down there after 7pm (no childcare) there's no way I can tell what the temp is at night  :( For the same reason, I'm unable to cover the plants with fleece at night time. I have been hardening the plants off now for a couple of weeks so I might just have to bite the bullet and shove them all in the greenhouse at the end of next week, come what may  :(   
Title: Re: Greenhouse temperature
Post by: mumofstig on May 11, 2013, 20:11
You don't have to go down at night to read the temperature  :nowink: max min/thermometers hold  the highest and lowest temperature until you reset it  ;) giving you an idea of your local temperature trends.
Title: Re: Greenhouse temperature
Post by: wil4025 on May 12, 2013, 10:48
Thanks for ebay link, will buy one of these.