Lemon balm needs temperatures of 70 degrees F to germinate, and the seeds should not be covered, according to one website I looked at. Seems a bit bonkers to me, if you want that kind of temperature, surely you'd need a propagator. I'm also puzzled because this blasted stuff used to pop up all over the place in my garden 25 years ago, apparently self set. I found it very invasive, which sort of suggests it grows all by itself... Might be worth buying one plant - in my experience, you'd need a flamethrower to control it by the following year.

I think they might need a spell in the fridge as the plant seeds freely in my garden especially after hard frosts.

From the instructions on the pack it says cover with 3-5 mm of thin seeding soil and place on a warm windowsill without direct sunlight and keep moist. On some websites it says do not cover so I sowed some more on the surface and its been 2 weeks and these haven't started either...I have chamomile, and curry plant in the same propagator and they all started within a week and the seedlings are about 1.5 cm tall. Im not sure if that propagator gets to 70°f/21°c though, its not a self heated, just a plastic one with a transparent cover on top.

It's unlikely to reach that sort of temperature without heat.

I wonder if it does keep cats away though - hadn't noticed it. But it does make lovely herbal tea. If it doesn't germinate and you want a bit send me a pm.

I can confirm it has no impact on cats at all - well, certainly not on mine when it was in the garden. I had 2 adult cats and 6 kittens for a while, and they rolled around in the lemon balm just as they did in everything else...

My cat lives quite happily with lemon balm self-seeding in the garden. She doesn't roll in it as she's to busy doing that on the catmint, but that's planted next to another citrus-smelling plant, lemon verbena which doesn't put her off a bit. Nor did the helichrysum I used to have.

I did not buy these seeds for cat repelling, although I have a cat problem in my garden...but primarily to get curry plant seeds which I have see nowhere else...

Do you think I should invest in a heated electric propagator? I also have a cold frame and a tomato grow house which might get up to these temperatures on a really sunny day, but not constant.

Either that or wait and try some more seeds later, when the weather's reliably warm/hot. Once you've got one plant in the garden, you'll have loads more eventually. But it occurs to me that, unless you're going to get a lot of use out of the propagator, its not cost effective - cheaper to go to the herb section at the garden centre and buy one lemon balm plant.