Verbena bonariensis and Pennesetum villosum germination success rate

I've been growing first-year flowering perennials from seed this year and have plenty of Echinacea, Achillea, Lupins and Ox-Eye Daisy seedlings to fill the garden with insect-friendly plants.

However, after three weeks in a windowsill propagator on the warmest windowsill in the house (above a radiator), I have five Pennesetum seedlings from 18 modules sown, and no Verbena bonariensis at all from twelve.

I'm happy to have any, so can't really complain, but was wondering if a low success rate for these two plants is the norm from seed?

 

A lot of perennials take longer than normal to germinate, so there might still be hope for them. I know Verbena Bonariensis self seeds freely in the garden and the resulting plants are hardier than the parent plant. Not sure if that's any help though.

 

I tried once with Pennisetum, and failed - so your five sound quite good!

Verbena is a funny one. The RHS seed instructions says cold stratify for two weeks, keep covered and takes up to 90 days. But like all seeds, they can't read and will usually germinate even if you do nothing special - just wait. But they are a bit erratic. I have grown Verbena that way. But one time, either with V. bonariensis or V. rigida (I forget which, but they are both similar), I left them for a long time and they did nothing. So I put them in the fridge for two weeks (cold stratify means cold treatment - fridge - but not freezer). When I took them out they did nothing for about a month, and I was about to throw them out, then one morning they germinated - all 500 seeds in the seed tray had germinated simultaneously!

There are a number of seeds that need/like a cold period before they will germinate. I have been growing Alliums - A. christophii, A hollandicum etc, that like that. So I sow them in a pot of compost, cover with a piece of glass and put outside in December or January, and let the cold weather do the trick. I have never got Alliums to germinate inside, but they germinate well that way. I suspect that anything that needs cold stratification could be treated the same way.

 

I'm glad five Pennesetums is a good thing, but as for the Verbena, who knows!?

The T&M packet tells me 24-27C, keeping compost on the dry side at all times, watering lightly as seedlings emerge.

Unwins' growing information tells me 10-15C, and keep moist.

Various gardeners' experience says that it easily self-sows in the garden.

Oh well, fridge it is.

Not sure what my better half is going to think...

 

Hi Iain and welcome to GC.

Verbena is a natural perennial here and I love them.

I have for the first time attempted P villosum (posh grass as I like to call it) here sent from a GC member and it germinated within the week in my outdoor living room as I don't have a greenhouse.

I can't control temperatures for my seeds .... we can be hot in the daytime and quite cold (to us) at night .... so I don't bother with what 'they' say and basically cross my fingers and hope for the best. I put my pots on a south-facing windowsill. My temps have been variable this past month .... last week we were 22-24c day temps, 18ish night ... this week we are 16-18c day and 8-12 night. Previously we were MUCH cooler and we're in rain season so damp but not humid.

PeterS ... I will write you in a few days about my various Salvias from you.

 

Iain I have the same trouble with conflicting statements. Luckily most seeds will germinate under a wide range of conditions - so normally I treat them all the same. But there are some funny ones. I have an RHS booklet that gives germinating conditions and it quotes up to one or even two years for some!

Verbena bonariensis wil seed itself freely, so once you have got it is likely to be with you forever. But I find that self seeding varies from year to year. One year I had millions of Verbena, and the next year I had many less Verbena but millons of Centranthus.

Vicky - I look forward to hearing from you.