[AlaninCarlisle]

Just noticed that some of my leek crop are seeding. Last season I blamed it on the mild dry winter and even drier spring and over-feeding with high N feed. I'm now wondering if it's something to do with germinating in March and planting out in May instead of using them to follow my early spuds in late June. Anyone got any thoughts on this?

[New shoot]

I think its more due to variations in weather.  Mine always seem worst if the weather has veered between very hot, then colder and back again.  They would naturally go to seed after overwintering, so if the weather has confused them into thinking this is their second summer, off they go.

[juvenal]

Sowed leek seed in January. Set out plants in May.

Half of leeks have bolted. Two months with almost no rain and then extreme heat must have something to do with it.

[Gardener and Rabbit]

What are the temperatures like in March, when you start them off? Just wondering if the problem is that they are getting a cold trigger to make them want to flower, right from the start.

[AlaninCarlisle]

I started them off in March in propagator. Probably about 25C at peak, dropping down at night. When I planted them out in May, temp was between say 8C and 16C

[mumofstig]

The propagator may be the problem from the start, they went from hot prop to cold(er) outside conditions.
Leeks are hardy plants and don't really need heat to germinate.

there is always the risk when starting the leeks off too soon that they suffer a check to their growth at some stage causing the plants to bolt later in the season. It is better to wait until late February/ March before sowing the seed. The seed can be sown outdoors in a well prepared seed bed,

https://www.nsalg.org.uk/crop/leeks/

[rowlandwells]

I've just planted my leek plants out in the allotments from growing in  module's there not all that big will they catch up before winter sets in I am usually a bit earlier in planting out

[Growster...]

What sort are they Alan? Are they earlies/mids/lates?

A chum here has leeks all gone to seed already, but he bought some plants already on their way, and wasn't to know what they were.

[Gardener and Rabbit]

I've grown Musselborough for several years without bolting problems,  which is interesting because my plants must be experiencing fairly similar periods of heat and drought to yours over the growing season. Like Mum says, mine are just sown outdoors in a pot, about mid March, so no additional heat or shelter.

[AlaninCarlisle]

The propagator may be the problem from the start, they went from hot prop to cold(er) outside conditions.
Leeks are hardy plants and don't really need heat to germinate.

I've been starting leeks, usually Musselburgh, in the propagator for at least 20 years,ever since I built it 21 years ago but this bolting has only occurred in the last two seasons




edit to clarify quote

[al78]

Here in the SE we had a warm dry first half of summer, now it has suddenly flipped to cool, cloudy and wet, just in time for the school holidays (it did the opposite last year). These pendulum-like swings in the weather patterns seem to trigger bolting in my experience.

I started my leeks in February indoors, no propagator, and they are looking good with no bolting, so I doubt starting in March would cause bolting later on.