Over wintering late planted fennel

Question

I was very keen to grow some fennel this year (doesn't it smell incredible?), but wasn't able to plant anything until quite late in the year, and so my plants are now only 10-20cm high and still in small pots.

Is there any way to over-winter them to give myself a head start next year, or should I just make some tea with what I've got / chuck it on the compost heap, and make sure I start earlier next year? I'm in the UK, Zone 8

If it's worth trying, should I bring the pots inside, or would the plants naturally die back and re-grow from their root stock if I just left them outside?

Any fennel growing tips would be appreciated, I'd love to have a good stock of them next year.

Answer 1

You don't say whether they're Florence fennel (grown for the bulb) or ordinary Fennel (Foeniculum vulgare). If they're the latter, unless you live in the Shetland Islands or the north of Scotland, I'd harden off the 20 cm ones and plant in the ground immediately. There's still plenty of warmth in the soil even if the air temperature is starting to drop. Depending on which part of the UK you're in, you might be okay planting out the 10 cm ones too, but don't forget they disappear in the winter, so you won't know what's survived and what hasn't till growth begins again in Spring. Ordinary Fennel puts down quite a long taproot, so keeping them in pots over winter, unless you pot on into very deep pots, isn't terribly practical.

I'm assuming you're thinking of selling on the fennel as herb when you talk about having lots available, because one or two plants is more than enough for culinary use by even a large family during late spring/summer and autumn. And once you've got even one plant established, it'll always be there - seems to be impossible to dig out and remove because of the long, long tap root.

Florence fennel, though, is another matter altogether...

Answer 2

Fennel is a perennial herb that is cold-hardy down to Zone 5. If your plan is to eventually plant them permanently outdoors I would almost consider transplanting them outdoors right away. However, you might lose a few of the smaller plants if they don't have enough root reserve built up yet, so a little extra caution might be advised.

If you plan to keep your fennel potted (for now), you have a few options. I wouldn't quite be comfortable leaving the pots outdoors unprotected all winter. Above ground, the soil in a pot is exposed to much more cold than the same soil would be if only the top were exposed. The soil inside a pot can actually freeze solid because of the increased surface area, killing most plants.

One solution to this is to plant the entire pot in the ground so that the top edge of the pot is level with the surrounding soil. When the weather warms back up (after the risk of heavy freeze is over) you can pull the pot back out of the ground. Another option would be to bring the pot inside to an unheated garage/porch area where it will be cool, but not so cold that the soil freezes inside the pot. When the risk of frost is gone you can put the pot back outside.