Last Frost Date? / When Can I Put My Plants Out?

I went looking for historical data about minimum night temperatures near here so I could form a view on when the min. night temeprature was unlikely to fall below 5C - and I came up with 20th April

Of course there may be frost after that ... but if it will, on average, only be a few nights, and none at all some years, then I don't mind carting things back in again ...

I have made a step-by-step guide on My Blog.

Some Nerdiness probably required ... :thmb:

 

I like your blog, and your garden. Although judging by the pics I wouldn't so much call it a garden, more like you have your own county

 

Yeah Kristen, you have an amazing garden, A country Estate, ive been keeping up with your blogs and you deserve a pat on the back, :ntwrth: What a Guy :D As for 20th April for planting out tender plants, Nooooooo Way Pedro I usually wait untill middle/End of May, on saying that I do live in the Northeast of England... Dee...

 

The one and only time I ended up with hypothermia happened on the bank holiday monday at the end of May one year. It had been red hot that day and still warm into the evening, and when I came out of a nightclub dressed for summer it was hailstoning so hard that lumps of ice were collecting everwhere. I remember going to the cash point to get some money for taxi fair, it was one of those jobs where you swipe your card to unlock the reception foyer door. I spent a good few minutes picking ice out of the slot just so I could get in to use the machine. By the time I got home I was very poorly indeed. Oh the joys of youth Now I take a coat when I go out

 

"As for 20th April for planting out tender plants, Nooooooo Way Pedro"

Toggle off and follow my instructions then please - I'd be interested to see if they give you a date for your location that you would agree with

 

"ive been keeping up with your blogs and you deserve a pat on the back"

Thanks! Battling with removing the weeds from the Shrubbery which I want to get under control this year (didn't have time to do much to it last year, other than Glyphosphate between the shrubs, and as they are small for their first couple of years I wasn't too bothered - but I hadn't banked on such a good growing season for the weeds last year!)

Ditto with the yew hedge we put in last year which was horrifically late for bare root plants (planted 28th April - I should have put them in pots instead) and now competing with weed growing between and through it ... so a bit of a challenge and a chore to sort out :(

 

"I usually aim for around mid May for putting my tomatoes in the greenhouse"

Greenhouse will probably give you a 5C lift over minimum outdoor temperature, won't it? Nights are short - so it will take time for the greenhouse to lose its heat. (Polythene would lose heat quicker, I would expect)

Dew point will have to fall to zero for a frost. Hadn't thought of taking that into account.

Are you and I the only two nerds on here who have looked at this then?

 

Kristen - Many thanks for a useful lead to the Wundermap - and to a subject that is important to us all. I have looked at my local weather station, which needs some time to be spent on it. I don't imediately see last frost dates, but there is loads of data to sort through.

John - I think we should ignore the Dew Point. This is the temperature at which the air can no longer hold all the moisture that is in it. At this temperature the moisture is released and condenses as dew. If the dew point is below 0C, it will condense as ice. The weather stations are primarily located at airports and the dew point is very important to them as it tells them about ice forming on aircraft wings. But it is not that important to us.

I recently been keeping some records myself :-

2007 last frost outside 11 April
2007 last frost inside 9 Feb
2007 first frost outside 20 Oct

2008 last frost outside 17 April
2008 last frost inside 25 March
2008 first frost outside 29 Oct

2009 last frost outside so far 8 April
2009 last frost inside so far 29 March (-0.1C) previous to that 5 March (0.9C)

The last frost inside is when the thermostat inside my summerhouse was triggered to turn the heater on. This happens when the temperature inside drops to about 1C. The last time that would have happened this year was 29 March - but I had turned my heating off by that time :D These times are for North Yorkshire - you soft southerners will be basking in the heat long before. :D

I record temperatures in several places. In general the temperature inside my summerhouse is about 3C higher than outside. But this is not a constant. During a prolonged cold spell, when the summerhouse gets no heat from the sun, the minimum temperature inside can be the same as the minimum temperature outside. I now have a greenhouse as well - and that performs essentially the same as the summer house. You have to be careful when measuring temperatures - it can vary from place to place. Two thermometers outside last year would vary by 2 or more degrees as one was set higher and more sheltered than the other. They both recorded the same when put together.

 

How are you chaps recording temperature?

I have sensors on a 1-wire network which monitors central heating stuff (I'm installing some Solar Panels and want to record data). I could stretch this cable into the conservatory ... but the greenhouse is too far from the house.

Edit: This guy is reasonable near to me (Colchester), and has some useful long term statistics - which I can't easily find a way of extracting on Wunderground, and he is also recording the Ground Minimum Temperature - which I find useful

 

I am simply using max/min thermometers and recording manually, once a day. Outside is a mercury one and in the summerhouse and greenhouse I have digital ones.

I am full of admiration for that Colchester guy. He has got it totally cracked. However it must take a lot of time and effort to get there. I am with Adam Moran http://www.gardenerscorner.co.uk/forum/showthread.php/digital-temp-monitoring-20774.html in his thread. It would be nice to have it all done for you. There are just so many projects that you could follow. At the moment temperatures are just a tool to aid gardening rather than an end in itself.

 

My El Cheapo 65-quid weather station should be OK (link in the thread you pointed to). But like you say, its all just more projects; mine has been sat in my office for a month (successfully measuring the temperature and humidity in the room!! but I'm pleased to say no wind ...)

I'm kicking myself because we had the Satellite man out to make some changes to our dish and I told him "Take that ugly aerial off the chimney, won't need that any more" ... and then a week later I bought this weather station which would be IDEAL stuck on the old aerial pole. Bother! So now I've got to find a pole or some mounting doubreys for the chimney :(

 

Kristen said.

It's possible to pick up a degree or two from the house if it's situated there above the house Kristen,funny a it seems when I go out early morning in my shorts for my ride the temperature difference tavelling past buildings is really noticeable it must be a couple of degrees,a couple of mornings this week it's been cool in town a mile or two out in the countryside there has been a grass frost.