Germinating Leeks: hotwater bottles and bubblewrap.

Mid winter isn’t usually considered the time to sow seeds; freezing temperatures, snow laying on the South Downs in Sussex for over a week. And now rain, leaving the ground cold and saturated. Yesterday, on our way to Eastbourne we passed fields that were nothing but lakes, and, with the forecast for more rain, there’ll be little sign of those fields drying our soon.

leeks under snow [1]

Still, it’s possible to start early crops of hardy vegetable varieties undercover, indoors, which is what I’ve been attempting with leeks. Since 2009 I’ve experimented with different ways to start leek seedlings early, so that I have large enough plants for cropping during the summer.

Looking back through my gardening diary I read this:
Early March 2009: I used old window frames to cover a bed for early salads and sowed my own saved leek seed alongside. I’ve a note that germination was fairly quick; sown on the 1st, germinated by the 15th, transplanted into the 1st early potato bed by end of May, so following rotation and in good time as a follow-on crop after potatoes. I need to remember that Spring 2009 on the South Downs was warm during the day, but moderated by cold winds and low night temperatures.

2010: continued sowing undercover in the allotment at the end of March, again transplanting the seedlings at the end of May. But looking at my notes it’s clear that both years we didn’t really have any leeks cropping until early/mid autumn.

2011: after the New Moon of 4th January I sowed two trays of leeks (9th January). There was a full moon on the 19th just as the leeks showed signs of germination. I made a 2nd sowing of two varieties on 17th February, just before the next full moon on the 18th, and both had germinated by 22nd. The trays were kept on shelving next to a north facing French window, so, cool. They were wrapped in bubblewrap over the top of clear plastic lids, and covered with old towels.

2012: I was preoccupied during January and February, so reverted to my March/May sowing and transplanting cycle.

And now, this year (2013), I’ve attempted early sowing again. But, because temperatures have been so consistently low, I need to modify my sowing methods to encourage germination. I don’t have a heated propagator, so I’ve worked out an approach that, I think, mirrors the way a propagator works: a tray of modules with compost (half and half sieved leaf mould and our own green waste compost) sat on top of two hot water bottles overnight to raise the soil temperature before sowing seeds. After sowing, this routine continued for four nights, with the tray covered with a clear plastic lid, a sheet of bubble wrap, topped by a couple of old towels. The seeds were sown on the 3rd January and all four varieties had signs of germination (below) by the 11th. So, once germination was assured, I gradually moved the tray of seedlings, covered with a lid and bubble wrap, into the kitchen extension during the day, then back onto the shelves by the French doors at night, for about a week. The tray’s now in the extension without a lid until the seedlings are transplanted into a seedbed, probably by mid-February – I may cover them with fleece  for a week or so until they are established.

leek seedlings

Leek and onion seeds take from 14-18 days to germinate within a temperature range of 7-24o C, so I’ve effectively speeded up germination to eight days. Poor germination is either the result of cold compost/soil or old seed; it can also, early in the year, result from swings in temperature, so hot water bottles need consistently reheating each night until it’s obvious germination is going well. Once you have small seedlings, a bit like onion ‘grass’, about a couple of inches tall, they’re hardy enough to leave in a cool extension, or even a greenhouse, to slowly grow for a month before being transplanted into a nursery bed. The seedlings, below, are now standing up more strongly.

leek seedlings indoors

Sowing seeds challenges the timeframes within which we live our daily lives, thinking in seasons, not months; harvesting last year’s winter leek crop reminds me to sow next year’s summer crop. Yet, because leeks grow so slowly, there’s always the possibility of catching up by the end of spring.

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