It is more the soil temp then air temp.

I have planted some of mine in zone 5b as part of an experiement already. But I usually wait till 5.15 or so to plant out and even so, I will need to cover them a few nights if it gets too chilly. Mother nature is always up to tricks with late season frosts!

Keriann~

Hi Tiffy.

We have not had a frost in several weeks in the 6/7 section of Massachusetts, and I still have to worry about having frost blankets in case a frost crops up in May. Indeed, I getting the frost blankets ready for tomorrow night when the temp is going down to at least 36, maybe lower. Since I am 'risking it' here by planting plants, I wonder if you are risking more because you are in a colder zone and you are planting tubers.

I am all for starting earlier than conventional wisdom, but given all the factors, including the ground temp and the potential for more frost, I would think you would have better putting them in pots for a couple of weeks.

That said, Sid's Dahlias in Nova Scotia has some wisdom about spring frosts on its web page:

"A late spring frost will kill young sprouts, but they will usually sprout again."

Mine are in the ground and starting to come up. Soil temp was 60 when I planted last week.

Thanks everyone. It's been drizzling and showering here for the last couple of days and coupled with work and gardening meetings, I have been forced to put my plan on hold. All things happen for a reason so I guess it's not quite time to plant, eh? :O)

Hoping to get some nice Dahlia tubers this weekend from the Nova Scotia Dahlia Society annual sale. Goodies are being sold early Saturday and I am looking for some medium sized orange, peach, and lilac colours. Looking forward to expanding my 'repertoire'!!

Don't get in a rush to plant early. Take your time and enjoy some late bloom. Steve S

How about container planting...I've planted my dahlias yesterday, then last night it went down to 34. One pot I was able to bring inside but the other I tried to cover as best I could. They looked a little droopy this morning--will they recover? What's the best way to cover? The pot is pretty heavy to move. I had coleus in the same pot, they definitely look gone. I don't know what I was thinking, just too excited for warm weather I guess. I'm in zone 6, NW NJ.

Every year in Quebec i plant mine early mine have been in the ground for about a week now I check them everyday so far so good they even pass the snow we got last week if we get a frost it will be a ground frost and some of mind are just about one inch high so they should be ok
Anna