How to over winter cardoon in 6b

Floyd, VA(Zone 6b)

I love the look of this large leafed plant. I understand it is a perennial. There are pluses and minuses there; the flower is beautiful. If it goes to seed, it can be very invasive.

How can I get the huge plant in one summer? Dare I try to over winter it? How?
If I should get flowers, should I nip the buds or let them flower and dead head?

I am looking for cardoon seeds right now. Any suggestions?

Rosemont, ON(Zone 4a)

Hi Gloria! I think you'll have to wait two years for flowers. I germinated 6 seeds (from Suttons, an English seed company) indoors in pots. Three of the seedlings died after planting out - we had a long drought that summer, so they had a tough time - and another two did not make it through winter, but the survivor is now flowering like crazy. Would you like me to try to save some seeds from it to send to you?

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Candler, NC(Zone 6b)

I'm in z6b also. I started some seed last spring indoors under lights and they germinated well with no special treatment except don't overwater. I planted some out as soon as frosts ended but if hardened off before going out, I tend to think they could take light frosts. Some did not get planted until late June. I am fortunate to have deep loamy soils and all got huge. Most of growth was in summer so the late planted ones got just as big as the early planted ones. Don't overwater young plants. As of now (Oct) some in the best soil have gotten 4+ ft tall and 5ft wide. (See pic w/ sunflowers for scale) Didn't expect this size and I had to keep removing lower leaves to prevent them from "swallowing" neighbors! I grew cardoon when I lived in z7b central NC w/ clay soil and they grew well but never so big. In z7b the inner center of the rosette overwintered for me pretty reliably with a generous sleeve of pine straw around the plant and a light covering on top. They never flowered until the second year. I'm new to 6b and have not yet tested overwintering here. I'm going to mulch just like in z7 and then temporarily cover more during periods when 15F & below might last more than a few hours; also when freezing ice is expected. Being a Mediterranean species, my assumption is that in winter the plant prefers dryish feet and not much dampness around the crown.

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Candler, NC(Zone 6b)

I got my seed from . A nice seed vendor!

Raleigh, NC

I had Cardoon last year ('giganta')--planted two plants in late summer in a raised bed (no clay), and both did well, but neither survived an early, brief cold snap with temps in the teens at night. The rest of the winter was very mild, but they did not come back. I've got one now that's been growing in a pot all summer, and am not sure what to do with it. Too late to plant it out, so I guess I'll tuck the pot in my protected "winter" area where I put all my potted plants, mulch well and see what happens. Hope it lives, as I love the sculptural effects and brilliant flowers, and really want one to survive and bloom.

And while we're on the subject...anyone in zone 7b or lower had luck overwintering Pineapple Sage? I hear its "iffy" in my zone, and mine was beautiful this year. Like to save it, if possible....

Lexington, VA(Zone 6a)

yotedog, I've actually had Pineapple Sage come back in my Zone 6 garden! Although I was never sure if it was truly the mother plant or just self sown from the year before. If you can take cuttings, they root quickly and you could try to save it for next year. I'm having the same "problem" here - my 'Golden Delicious' is absolutely gorgeous this year and I don't want to take a chance that I won't be able to find it next year, so I'm going to attempt to grow on some cuttings!

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Raleigh, NC

Oh that's beautiful! That is about what mine looks like, and just starting to bloom well. Funny thing is, its huge, but was growing in a 4 inch pot, which I buried and forgot about last June (I buried it when I went out of town, to make sure it would survive no watering--meant to dig it up and relocate it, but forgot). Wonder if its still in that pot, and I can just dig it up and prune it way back to save it in the house, or if its completely broken through the pot? My guess is it just grew through the bottom and the pot is still intact......amazing, these plants will to live, huh? Well, except for the really expensive ones, that always die!

Lexington, VA(Zone 6a)

As vigorous as these Salvias are, my guess is that it most likely has grown through the bottom of the pot! It's worth a try though to dig the plant, pot and all, and see if you could overwinter it or just take some cuttings, they might be easier :) I forgot, I actually have some of the plant from cuttings I took earlier this summer growing in a container. The container has to come inside to overwinter the non-hardy fern that's planted with it - so I might get lucky!

Candler, NC(Zone 6b)

Bumping this very old thread to add to my comments above.
Proof that plants don't read: I have always been told and read that to overwinter cardoon in Z7 & Z6 you have to give protection e.g. pine straw and best if location is warmish and dryish during the winter. I have a parcel with 30' elevation change with riparian bottom land that is always cooler and moister than the higher ground. Have overwintered cardoon for several winters now and don't bother to mulch. Guess what - the ones in the bottom in the colder, wetter soils winter over much more reliably than the ones upland. My plants tend to not be strict biennials - new starts set out in spring overwinter then bloom the next year. The blooming crown dies back and typically there will be a side shoot or two that makes it to a third year. Three years is the max I have gotten out of original plants.

The soils in the bottom land are deeper and richer so plants get larger there. Photo in my entry above is a robust plant in the bottom land. So greater vigor may play some role. Mulching would probably improve chances bottom & upland. We typically get into the lower teens numerous times a winter and single digits are not uncommon, especially in the bottom. Wish I could recall the original seed source but alas - lost from my records. However, no variety was specified originally and I am using collected seed. This greater success with the colder, wetter, unmulched regime goes against conventional wisdom. Go figure.

BTW: I have had no luck with direct sow seeds. They seem to either rot or get eaten by voles.

Candler, NC(Zone 6b)

Add on: Erratic temperature swings are as much a cause of winter damage in many plants than lows per se. This problem is notorious in the upper south. One speculation of mine for the cardoon concerns this. The bottom land soils stay more consistently cold and nights are colder there as well. This keeps the plants more cold acclimatized. Also of note: though the bottom soils are moister they are still well drained and rarely stay saturated for very long.

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