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Can you help me nurture my indoor-sown Achillea seedlings?

Hi all,

First post, lovely to meet you all. I am a propagating novice having difficulty working out what to do with my indoor sown Achillea seeds and hope someone can give some tips.

As per the packet instructions I sowed these indoors in mid October, and pricked them out recently. So far, so good.

Now the instructions tell me to “grow on, and acclimatise and plant out once danger of frost has passed“.

But they don’t explain what “grow on” means. How best do I nurture them for five months indoors (assuming frost danger usually passes by mid-April here in London)?

How much light? As much as possible? Would a grow light help?
Keep them moist, presumably? Do capillary mats work well?
Keep them in a cool or a warm place indoors?

I had hoped that by starting these off early indoors they’d be much stronger plants, but I fear ending up with spindly, sickly specimens, if any at all.

Any help much appreciated. The pictures show the recently pricked out seedling, and those yet to be pricked out. And a cheery view of the garden this summer.

Many thanks.


  • PosyPosy Posts: 3,601
    What a pretty garden! Do you have a cold-frame or sheltered area outside? Your seedlings would probably be better out of doors most of the time, but with some protection. They need cool, bright conditions to grow well. Perhaps you could rig up a simple frame with a glass cover. Achillea are pretty tough and London warmer than many areas so they should be ok.
  • Pete.8Pete.8 Posts: 11,135
    They do need to be outside really.
    If you keep them indoors, the warmth will force them to grow, but there's just not enough light now until Spring, so they'll stretch and get very leggy, and not be of much use next year.
    If you keep them outside, the cool temperatures will stop them growing, something such as Posy has suggested above in a sunny spot would be ideal.
    If you can't cover them, you could put them outside in the day in a sunny but sheltered position, then bring them in at night. After a few weeks they'll be ok to be left outside all the time.
    A lovely display you have there.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • Hi Posy and Pete

    Many thanks for your helpful replies. It sounds like outside is the way to go so I'll see if I can rig up some sort of cold frame for them.

    I am still intrigued as to why so many seeds come with a choice of planting indoors September-November or outdoors from January. The former, with its implication of a head start for a stronger plant come the following spring, seems a bit of an allusion.

    It’s fascinating stuff and I am determined to learn more!

    Cheers, Johnny
  • Pete.8Pete.8 Posts: 11,135
    Achillea are very hardy and will survive temps down to -20C
    But you have little babies, so they need a bit more TLC early on.
    Once they're used to being outside they'll survive whatever our weather throws at them

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • FairygirlFairygirl Posts: 54,353
    In their normal world, they would seed and grow more slowly, so they wouldn't get leggy. Some would be eaten, or succumb to rough, wet weather, and the ones that make it, will be sturdier and tougher than the ones you sow under more cossetted conditions, because they've been gradually accustomed to the growing conditions and climate.
    It's also why plants produce so much seed - lots of them don't get to be the end product!
    What you're really doing is trying to replicate nature, but also get a head start on it, but it requires a bit of extra attention   :) 
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Nanny BeachNanny Beach Posts: 8,669
    Good advice on here, get them oudside, watch out for slugs though, you dont need grow lights or anything else fancy.  You are so lucky to have the London microlimate, frost finnishing by April, I am in the SE 10 minutes by car from the sea, we dont get many frost, but I wouldnt trust frost free till the last day of May
  • Thanks Pete and Fairygirl, out with the cosseting and in with some hardy outdoor love for them. Nanny B, your experience brings home the boon of a microclimate - last day of May in your part of the SE is a real eye opener. That's about a month later than here, and only 70-odd miles separate us.
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