Friday, 12 February 2010

Waiting for spring...

Allotment bloggers are looking for signs of spring, and for my part I've seen my first snowdrops of the year in the wild. I'm itching to get started. Prompted by other blogs I've already been panicked into buying seed potato far earlier than I intended. At least I got what I wanted. But now I see blogs where seeds are being popped into modules and I'm scurrying off to check whether I should be in full sowing mode yet. Let's be a bit scientific about this.

Here I must point out that I am a fan of outdoor sowing. My plot is several miles accross town and doesn't have an operational greenhouse. At home I do have an unheated mini greenhouse that amounts to a glorified transparent Wendyhouse. There isn't much windowsill space either. And given that I have to transport any homegrown seedlings, wherever possible I sow seeds straight into the soil at the plot.

I've got a god idea of the order of sowing (parsnip, broad bean etc)but how soon can I get started?

The key factors has got to be (a)the seeds' germination requirement and (b)how warm can I rely on it being here in Edinburgh and when. So here goes.

How warm does it have to be before seeds germinate?

There's a cracking table circulating on the internet that results from some experimentation done in the eighties. The only problem is that the information is a bit too concentrated. Here's the chart:

note - click on frame to expand charts

Not clear is it (and there are 3 gaps with no data)

So extracted from the chart here's the information about "% germination" at different teperatures:

and here's the information about days taken to emerge at different temperatures:

The dark green boxes indicate the best germination rates, but the light green boxes indicate enhanced germination rates. The white boxes inicate unfavourable conditions and the blank boxes indicate that it's a waste of time even trying under theses conditions.

When you've got maximun % germination and quickest emergence then you're on a surefire winner. But another factor has to be added that is 'earliness' because its all very well germinating beans at the height of summer but if there is not enough time for them to grow beanspods before the first frost kills them So generally there should be a bias to the left most green shaded boxes.

How warm is it in Edinburgh at this time of year?

or pictorally

Crikey this is bad news. The average Max temperature is 18 whereas my Optimum Germination charts suggest you need at least 20, better still 25 to get the best results. The record high in the last thirty years is less than 30 degrees. Conclusion, in theory I shouldn't be getting a return off my plot at all?

I'll have to return to this after I've had a lie dow. But in the meantime I can see that it's far too early for me to start sowing.

Song of the week: Wonderful World (Don't Know Much)~ Sam Cooke


  1. All I know is that it's icy cold here in the Welsh hills today!!!!

  2. Crikey hope you recover OK after that shock! Thanks for the info, one to digest after the kids are in bed though. The only things I'm sowing direct in Feb are broad beans and parsnips. Everything else is on the bathroom windowsill and then into an insulated, but unheated greenhouse. Sunflowers are two inches high already, now that must be too early, forever the optimist me!

  3. I start most things off at home, but have held off sowing until now. I'm going to start my first batch of seeds off today, which will be grown on my windowsill until warm enough to transfer into the greenhouse.

  4. Hi Lynda - I hope you stayed in and watched the rugby. (Daylight robbery that was!)

    Dynamo - You sound like you're on track. We are a few weeks later north of the border and I guess I was filling in my time by looking too deep into the figures. Things are slower here, but they do grow. There are quite a few factors to take into account.

    Jo, I'm coming around to adopting your progressive scheme. More to follow in Back To School part 2, but I've got to lime next year's brassica patch today. (I'll leave the theory to my work lunchtimes.)

  5. Thanks for the soup recipe, had some for lunch and it was lovely. Had some parnsips and sprouts from the plot for tea, not bad this veg growing lark!

  6. No sowing for us yet either - later sown catch up, earlier sown struggle!

  7. Thanks, Mal, just what I needed to stop me from sowing stuff which would only end up sad and leggy on the window sill. Reading the blogs of our friends in the South was making me want to make a start, even though I've always thought that March was too soon in Scotland. One old boy said you should wait till you can sit on the ground with your breeks down, but that might shock the douce citizens of Embra!