Giant (Alpine) Lobelias

[Vinny 123]

These plants have held the same fascination for me as some of the high altitude Rheum species for a very, very long time. I have seen the occasional Rheum seedling/small plant for sale, and resisted the temptation each time, but never noticed any of the Lobelias.

A quick search of the forum doesn't find anything significant, so has anyone tried? I was very surprised recently to find that a few species, African and S American, are available as seed, at vastly differing prices - species such as deckenii, telekii, wollastonii etc.

For the grand investment of not much, I have recently (3 weeks ago) sown two species. Both had been cold-stored so there was a hope for some green specks by now, but not so far.

[Diane Whitehead]

I have sown seeds of many species but the only one that flowers regularly in my garden is Lobelia tupa from Chile.
My plants are 25 years old.

[Vinny 123]

The first time that I became aware of giant Lobelias, was a wildlife film, near certainly made in Rwanda, which followed a group of mountain gorillas up above the tree-line where they ripped tens of years' growth to pieces to eat the flowering spikes.

Pretty much the only conventional, low altitude lobelia that is reliably hardy in the great bulk of the UK is siphilitica - it it wasn't so free with seed it would be much admired. Giant lobelias are hardy, they freeze regularly in habitat, but will probably need perfect drainage.

[Carolyn]

Like Diane, i grow Lobelia tupa, which seems hardy here once you get it through its first winter. I have grown L bridgesii for several years and it seems hardy too. Lobelia siphilitica is one of my favourites, as it provides valuable colour in Aug/Sept. I have recently bought a dwarf form of this. Last spring I bought L montana and L laxiflora angustifolia from Woodlands Plants. I haven’t had a chance to test their hardiness yet, but I have some cuttings which I will overwinter in the greenhouse as an insurance. I’ll be sending seeds of tupa and bridgesii to the Seed Exchange.

[Vinny 123]

I suspect that most Lobelias will have been OK for the past 2? 3? winters here in the English midlands, especially if mulched well and/or in a sheltered spot, but when we get what used to be a traditional winter again................
I have kept Impatiens tinctoria going for a few years here - a 15cm high ring of 12mm chicken wire stuffed with dry leaves and topped with a pane of glass once the first frosts have killed the top growth, so more care with Lobelias? I am unsure whether the large, deep tuber made by I.t. would be an asset or hinderance to survival, possibly that depends on the severity of the winter.

[majallison]

People in Cornwall are successfully growing Lobelia bambuseti, which grows in montane forests in East Africa & is closely related to the high-altitude species, but I don't think L. bambuseti has much frost tolerance...

[Véronique Macrelle]

I managed Lobelia tupa from seeds for 2 years, until the splendid flowering, but they died the following winter in the ground. I would try again if you send seeds to this year's exchange.
do they need a very draining soil?

the sowing is not very easy, I find, it fakes a lot to get only a few. and the seeds are as fine as dust

here is the plant sown in January, during its first winter, spent in an unheated greenhouse

[Vinny 123]

People in Cornwall are successfully growing Lobelia bambuseti, which grows in montane forests in East Africa & is closely related to the high-altitude species, but I don't think L. bambuseti has much frost tolerance...

Borderline hardy according to seed suppliers, whatever that really means. Photo's online of plants in habitat in Kenya show reasonably lush vegetation, at least one very close to hillside cultivation. It also seems not to form the very attractive, very low-growing rosettes that the high altitude species do. That said, the more time spent searching, the more species there seem to be, with various growth forms.