jody, it just so happens that I am going outside today to dig up my dahlias. I don't know about in your zone though. It might be possible to mulch heavily, but hopefully someone in your zone who is familiar with dahlias will post.

Sorry, I know I'm of no help whatsoever, lol! Does your MIL live in the same zone, and does she (successfully) grow dahlias?

:)
Dee

How well dahlias overwinter in the ground will depend on your soil conditions. If your soil does not freeze more than a couple of inches or so in winter and is very well draining, then you should be able to safely leave them in place. Tubers are damaged at 25F - because they need to be planted fairly deeply, that generally means they can withstand winter cold that allows for only slightly frozen ground (2-3" depth). Which is probably what you are looking at in zone 7b. What is of more concern is the ability of the soil to drain very well - while they can tolerate some cold, they will not tolerate soils that remain very wet in winter. The tubers will simply rot. And mulching can help to insulate soils against freezing, provided you can provide the necessary sharp drainage.

To be on the safe side, digging and storing is perhaps your best bet. And now, after a couple of light frosts, is the best time to do so.

MIL lives with us. When she was widowed for the second time and her health was deteriorating we bought a house that allows her to live with us easily. DH is the eldest son of an Irish Catholic family :-) She is my greatest champion in the whole world. My mother and I had a difficult time, MIL and I have the relationship I craved with my mother.

She loves Dahlias, so I planted Dahlias this spring.

I'm going to dig them tonight. Better safe than sorry, they were really beautiful this year, although they got a lot taller than I expected. Supports will be in order next year.

From the North Carolina Extension Service:

"In Zone 7b, dahlias sometimes overwinter in the ground depending on soil drainage and severity of the winter. It is recommended the tuberous roots be lifted and stored during the winter. After a killing frost, cut the foliage back 2 to 4 inches above the ground. Lift each clump separately with a spading fork. To avoid spearing tuberous roots, begin digging a foot away from the center of the plant. Gently brush soil off the clump of tuberous roots. Spread the clumps in a well-ventilated, shaded area to cure for a few days. Do not leave the tubers in full sun. Dust injured portions with sulfur to inhibit diseases. Pack each clump upside down in a ventilated box or basket using slightly damp vermiculite, perlite, or peat moss to cover the clumps. During the winter, the tuberous roots should be stored between 35 and 50 oF and should not be exposed to hot or cold drafts or damp or very dry conditions. If the tuberous roots begin to shrivel during the winter, sprinkle lightly with water."

Thanks, gardengal and eric for the great information. I have grown Bishop of Llandaff for several years in pots and they came back every time. This year, I put them in one of my borders and was going to leave them there through the winter. After reading your posts, I am planning to dig them up TODAY. I doubt the drainage in my border will be good enough.

Dahlias are not commonly grown in our area and I have only tried two or three over the years. I planted some new ones this spring and they were a disapointment. The plants look spindly and didn't fill out well. They are in full sun, well amended clay (manure), and have steady moisture. I planted them about 3 to 4 inches deep. Any thoughts on why they may not have done well?

One more thought, if you have a spare tuber you could try leaving it in, put a pail lid or something over the spot where it's planted. This will keep it from getting too wet. Tubers rot more from the wet than the cold. As long as the tuber is planted below the frost line it more than likely come through the winter. I have done this the last few years and it has worked for me, I am in zone 8 though.
As to you're Dahlias looking spindly, I found when I was into growing Dahlias, being I'm on the west coast the varieties I bought from back east didn't do as well for me as the the the ones I purchased from around here. Maybe something to do with the growing conditions certain varieties are used to. You could also try pinching out the growing tip after two or three sets of leaves, this will make a bushier plant.

A......

Jody, what a sweet thing to say about your MIL! That's great that you have such a wonderful relationship!

Donna, for what it's worth, I had a lousy year with my dahlias this year (I even posted a thread about it earlier in the season!). They made up for it a bit with some late blooms, but overall there was just not the growth and bloom that I usually get. I was kind of bummed because I gave them a prime spot in the garden this year too!

:)
Dee

Great thread about about dahlias... here's one more!

I grow dahlias at the end of my garden where there's continual sun but that's the "downhill" part of the flower bed & it gets lots of water runoff, so I've always treated them as annuals. They were beautiful this year and I hated to see them end for the season.

Well, I was digging them up when one clump came out of the ground with a whole pile of nice, plump tubers at the roots. These things were enormous...like sweet potatoes! So naturally I am drying off the dirt/roots and storing them indoors for next season. Hopefully they'll survive my storage technique and be even better next year.

Molie