Getting Pennisetum through the winter?

Nollie

I’m not a big fan of grasses so I’m afraid I don’t know much about them, but I do like Pennisetum. I’ve had them dying in the ground before, winters can be very cold here, as low as -8c, but not usually wet. I plan to keep them in pots in a free draining potting mix this time, so I can bring them in. The only really frost-free place I have is a very dimly lit garage, just one tiny window. Are they OK without light? Do you just forget about them or do they need some moisture?

Any tips about care in general but especially overwintering would be gratefully received, as  I have just bought several large specimens of this one, Pennisetum advena ‘Rubrum’:

Loxley

I've never overwintered Pennisetum, but I would have thought light wouldn't be required when the grass is dormant. (After the foliage has been killed off by frosts). You'll need to keep the compost moist, but not wet I guess. Seems a bit of a hassle but it is a nice grass.

Nollie

Lucky you! I think it’s a combination of my (improved) clay soil and winter frosts/temps that did for them in the past @Loxely. I need plants to be a little hardier than it’s H3/-5 rating to survive in the ground up here in the mountains. I can usually get dahlia tubers in the ground through the winter if I mound them heavily, but its risky. Dahlias are cheap to buy though, these were not!

Good to know they won’t need too much light though, thanks.

Marlorena

I've tried this plant several times and did not survive outside here.. a series of minor frosts does it in, never mind -5..  I even tried cold greenhouse and it didn't survive there either.. it's an annual really for us.. but my book by specialist Roger Grounds says one can divide the plant in autumn and take small rooted clumps and pot on, keeping them indoors over winter.. a bit of water now and then.. I've not tried this.  A garage should be alright,  I wouldn't worry about the level of light as we can do this with roses too..

Pennisetum orientale, alopecuroides, and macrourum all hardy with good drainage outside here..  I've even lifted and divided in autumn and replanted these ok but they will just sit there and not do a thing, no root development.. so Spring is best for that.

Fairygirl

They don't survive here at all - any of them. Wet cold is lethal for them, which is what we get a lot of,  although we often have temps well below minus 5 and 6, and for long periods which doesn't help either. 

pitter-patter

I have overwintered mine, but made the mistake of splitting the large plant I had into smaller plants. It’s been slow to recover and grow and it’s not making a big impact in the garden this year. I really like this grass, but I’m not sure it’s worth the effort to treat it like a tender perennial. Maybe if I had a greenhouse.

https://forum.gardenersworld.com/discussion/comment/2313189#Comment_2313189

punkdoc

Rubrum is probably the least hardy of the Pennisetums, they need a heated greenhouse to survive.

Fairygirl

I'd agree - they're not even frost hardy, let alone anything else 

Nollie

That’s great, thanks everyone, I knew they were tender, but thought they were too beautiful to pass up. I’m known in the GC as the nutty foreigner that buys all the weird stuff they get on remainder. Like the time I snapped up that rare oddity Verbena Bonariensis, had a curious crowd of staff peppering me with questions then, Bless!

Good to know it keels over at touch of frost, I will get in early and keep it slightly damp. My garage has some low level heat as it houses the boiler, so that should help.

They are fairly large plants, but I won’t try to split them as the size was the appeal.

It was RHS that said it was hardy to -5m and only needed a cold greenhouse. I do find their info often doesn’t match reality, so thank goodness for you guys 😊 

pitter-patter

Very beautiful on closer inspection as well. I love the small pink bottlebrush flowers.

Fairygirl

They're very attractive @Nollie, and it's a shame they aren't tougher. Fingers crossed the garage will be light enough. I expect you'll just have to judge it when they start back into growth. 
Either that - you'll need to buy/build a little greenhouse. That'll get the tongues wagging even more