Grape vines that won't blossom

Asked August 25, 2019, 6:05 PM EDT

I live in Wolverine, MI which is considered a Zone 2. We have very sandy, acidic soil. I've had grape vines: (1) seeded concord, (7) unseeded concord for 10 years. Full sun on the grape arbor. They produce beautiful vines and leaves. What do I need to do to make them blossom? It's been 10 years and never a single blossom. I asked the Minnesota extension (didn't know MI has one) and they said it was probably "non-fruiting grape stock". I purchased them through a MI catalog company, so I don't think that would be the case. Please help me before the grapevines go to the compost pit.

Cheboygan County Michigan

2 Responses

The most likely cause is death of the buds due to winter cold or loss of the shoots to spring freezes. Do you often see poor growth early in the spring? Do the shoots get killed by a freeze after growth has begun?
Concord grape bud actually have 3 buds in them a primary, secondary and tertiary. These buds have the new shoots and flowers already formed in them during the winter. When the winter is too cold (about -20 F) the buds can be killed. The primary is the first to go and it is the most fruitful, the secondary has about half as many flower buds and the clusters are smaller. The tertiary buds do not have any flowers just a shoot and it sounds like you are getting lots of tertiary growth. Perhaps the vine is too exposed to winter cold on the grape arbor and is injured. Generally Concord is grown on its own roots so the rootstock theory does not hold water for me. You you get any shoots from the base of the vine? You should save a couple and lay them on the ground. You can cover them with straw but you probably get enough snow to protect them. Pull them up in the spring and the shoots growing from the protected canes should have flowers on them. That should solve the question of whether these vine just don't bloom or they are being injured by cold. In the spring when the vines begin to grow they are very susceptible to freezes and as the bud turns green and temperature below freezing will kill the shoot. You will see dead brown shoots and then new shoots coming out several weeks later. These are usually tertiaries and have no fruit. We get a lot of spring freezes down here and grapes in low areas suffer the most. Without more information I am only guessing. It is extremely unusual to lose the entire crop. Uusally there are still lots of buds with flower clusters left on the vine. To lose the crop every year for 10 years does not make much sense to me other than it is the most likely explanation for why you see no bloom. I attach a picture of a shoot killed by a spring freeze and the new growth

Thank you so much, you sent a picture similar to what I see every spring. I checked back into my garden journal to confirm what I saw with the picture you sent. What you described is probably what's happening. My primary buds are freezing during winter, that makes perfect sense. My grapes start putting forth the secondary buds about the end of April or beginning of May. Then along comes the last frost of the season (usually the last week of May rarely into June) and all I'm left with are the tertiary buds. I am going to buy some straw this weekend and lay some shoots on the ground. I would love to give you an update in the spring. It's already getting into the 40's at night up here right now, but I should have time to get them going before the first frost. Again, I am so grateful for your response. Sincerely, Mary Ford