[francisgreen]

Ok, I have purchased a digital thermometer off ebay and it is telling me that inside my small plastic Argos tent last nights min temp was 5c and today it got up to an incredible 27c!

Will this much variance upset germination? Should I open the front during the day?

[tam]

I'd be tempted to test it midday with another thermometer just to double check that reading is correct. Did you remember to zero it first? It's not recording the previous highest temp from in your house is it?

[Coltar223]

You are talking about air temp. rather than soil temp. I hope.!!

Generally soil temp needs to be at 7C or above for most germination. Some cooler crops will germinate at 4 or 5C but very slowly.

If you are talking air temp then you really should be venting if you have any germination .
At 27C you will cook seedlings!!

Take note of the weather forecast the night before and adjust the tent first thing in the morning. As you have found the air temp on even a partially sunny day will build up rapidly.

Good luck.

[Eatyourgreens]

Also be aware that digital thermometers can be just as unreliable as standard ones.

I have been a tropical fish keeper for years and regardless of price, or supposed quality I test any thermometer I acquire agianst a proven food grade glass thermometer I bought many years ago in a home brew shop.

It is wise to do a few standard tests at three temperatures (High medium and of course low) and then make a note (Mental will do) that this thermometer is say 1 degree high or 3 degrees low or whatever it is.

Two other points.

1 Never use a thermometer in sunshine or even direct daylight as this will alter any reading.

2 As others have mentioned, it is probably the air temp so much more volatile and a bit of ventilation is a good thing if needed.

Bob