Soil warmth

[LeifParticipant]

I hope people don’t mind a bit of a ramble. Hopefully it will illicit informative comment.

I am fairly new to growing in beds, having started three years ago after many years of container growing, and this year I sowed seed in beds – clay soil with lots of compost – with and without a cold frame on top, and in containers on a path against a south facing wall. The carrot under the coldframe appeared in a week. I was surprised that the carrot in the container did the same. The carrot in the uncovered beds has yet to appear. The spring onion and Pak Choi in containers, and modules under the coldframe germinated very quickly. I know the books say that cloches warm soil, but I’m surprised how effective they are. I’m also surprised by the effect of the path and wall. Next year I will start seed under a coldframe in February. I guess the only caveat is that some sun is needed.

I think I will order another coldframe . I have a glass and aluminium one. I have been pondering a greenhouse purchase, but coldframes do allow the cover to be moved around the garden, as crops are rotated, whereas a grrenhouse is fixed. I suppose for allotments a coldframe is risky since it can be stolen easily.

Incidentally I am near Basingstoke, so not the warmest part of the country, but not the coldest either.

[RhysParticipant]

Leif

I’ve noticed a very big difference this year between mid-March sowings and early April sowings, irrespective of whether I’ve sown in the soil, sown in modules in an outdoor lean-to mini-greenhouse or whether I’ve done it in unheated propagators indoors with lids on.

Beetroot:
Boltardy sown 16/3 indoors in modules – germination time: 12 – 16 days;
Boltardy sown 24/3 in a sunny area of soil – germination time 13 – 18 days+ (still a few gaps in the row);
Pablo sown 5/4 indoors (2 days after full moon on a Maria Thun root day): >90% germination of 60 seeds in 15 modules within 6 days.

Radish:
Nelson sown 06/03 in between garlic rows – germination time: 15 days +;
Nelson and Prince Rolin sown 24/03 between garlic rows – germination time: 11 days +;
Nelson sown 05/04 in between parsnip rows – germination time 6 days+ (about 12 seedlings already through in a 3 metre row);

Cabbage and Cauliflower:
Durham Early and All the Year Round sown 13/03 in modules indoors – 10 days to germination;
Landini F1 sown 08/04 in modules in outside lean-to greenhouse – 4 days to germination;

Lettuce:
Lollo Rosso Red and Bionda a Foglia Lissa sown 13/03 in an unheated propagator indoors with lid – 7 days to germination;
Bionda a Foglia Lissa, Lollo Rosso Red and Passion Brune sown 02/04 in the identical unheated propagator also indoors with lid on (two days before full moon on a Maria Thun leaf day) – 4 days to germination;

I”m based in NW London so probably slightly colder nights in late winter/early spring but perhaps slightly warmer days.

My lean-to was under £50 and has four shelves of about 2m * 1m. It has loops to allow you to tie it to something solid as it will blow away/over in the wind when it isn’t weighed down on the bottom shelves with something heavy (like a deep tub germinating leeks).

[LeifParticipant]

Thanks Rhys, that’s very interesting. There does seem to have been a sudden temperature jump between March and April this year. Still, leeks and carrot in a coldframe germinated a week or two quicker than in beds, so next year I’ll try some much earlier sowings. Wind is an issue isn’t it with light structures! The pegs on my second (light) coldframe seem to do the trick.

[Author]

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