Hey, Christie.
'Silk Hope' is a M.albaXrubra hybrid, a favorite of Dr. A.J. Bullard, the long-time NAFEX mulberry consultant. Dr. Bullard said of it in 1997, "decent blend of acid/sweet, good berry size, extended ripening season, and the added bonus of holding dormancy and not being cold-tender."
He ranks SH and Ill.Everbearing as 'second-tier', below M.nigra, which is 'out of the picture' for most growers in the US. SH outperforms IE in his NC orchard.

I have Silk Hope grafted on a seedling M.alba. Finally got around to putting it in the ground last year, but it did fruit, albeit lightly, while still in a 3-gallon pot. Fruits were pretty small, but I suspect that's due to it fruiting while imprisoned. After an opportunity to root out into some real soil(it's planted just outside one corner of the barnlot), fruit size, quality, and quantity should improve.
I don't know what BRN uses as understock, but I'd guess it's probably seedling M.alba.

I contacted Burnt Ridge about their rootstocks because they sell Russian Mulberry rootstocks, so I imagine that's what it's grafted onto. But you can e-mail them, they are very helpful. (They also sell scionwood, they said, of most things on their site!)

Carla in Sac

Sorry for not getting back. Thanks for your replies.
I got an email that my order is on it's way and I still haven't decided where to plant the mulberry. We used to have a wild mulberry that produced lots of berries at the corner of our yard and didn't have much trouble with stains on the driveway/sidewalk because of the distance (about 25 yards) I assume this tree will be similar.
One thing I forgot to check on is whether it will be susceptible to late frosts. I couldn't find anything just now when I did a quick search.

Hello,

Late is better than never, eh? I spoke to Dr. A.J. Bullard and asked about the Silk Hope variety. He says that his Silk Hope tree(s?) has survived -11 F without problems.

Burnt Ridge claims zone 5 for Silk Hope, Dr. Bullard has observed zone 6a hardiness himself, so perhaps the zone 5 claim is credible. Raintree Nursery claims zone 7 hardiness, which seems pessimistic, but it may be a function of the rootstock they're using.

Best,

--PeterM

Since mulberries fruit over such a long time period, usually you don't have to worry about occasional late frosts. New flowers will open after the frost.

Isn't Dr. Bullard east of Raleigh? That certainly wouldn't be zone 6. I think that would be 8a if not 8b.

cousinfloyd: I'm going by the temperature he said Silk Hope survived, which is 6a zone (-11F). Dr. Bullard's residence seems to be in zone 7b, so I guess he got a cold snap which Silk Hope survived without any damage he saw.

--PM