Pruning Grape Vines

[Gene45]

I have five Valiant grape plants , (concord style, supposedly the most hardy grapes I could have here, Alberta ) They are planted on the southeast side of my house , with an automatic watering system . The pants are 5-6 years old and seem to winter OK. They start from the ground again each year, i.e the old vines are basically dead after the cold winter, which can get to -40F.

The vines grow 8- 10 feet in one year, but produce very little . The best year was 36 pound of grapes from four plants, but more often it is 6 pounds.

My question is about pruning. Should I prune them during the growing season? I have to prune them to find the grapes and keep them from taking over the wall of the house. They climb.

Also is there some special fertilizer I should use?

 

[surlees]

Without going into a lot of detail, the answer is yes you can prune them during the summer. It's called "hedging" and is using done to control vegetative growth and balance the canopy with berry and root nutritional needs. Energy that would otherwise be expended on growing leaves is redirected to the grapes. Ever notice how vineyard canopies are head high and not flopping onto the ground.

Some grape varirties are more vigorous than others and soil structure and fertility plays a major role. Determining how much canopy to retain is part science and part experience. The whole subject of pruning, trellising, and fertilizing encompasses volumes. Get some good books on the subject.

BTW, the reason you're not getting any grapes is because grapes develop on the previous year's wood. If you're pruning to the ground or they're dying to the ground each year, you'll never have any grapes. It typically takes 3+ years for the trunk to develop enough size to support the canopy and yield mature grapes. Again, get a good book on the subject.

 

[Gene45]

I don't prune to the ground. Most of the old growth is dead and dry after winter.
The branches left are ~4 feet high.

 

[surlees]

Then you should prune during late winter/early spring to remove all dead growth and get the vine back to a managable size. This also helps to train the vine according to the type trellis you have or want. As I said, next year's grapes grow on this year's wood so you want to leave a trunk and some healthy canes. Do some research on different trellis styles and summer canopy management specific to this variety.

 

[Gene45]

I thought I was doing research by asking people who know more about it than I do.

 

[surlees]

I'll have to bow out then because I live in a vastly different climate than you and I'm not familiar with your growing conditions.

 

[grapeman]

I don't have a lot of time right now as I am in the middle of harvest and crush, but will note that Valiant is good only to about -35F so if you get to -40F you will get bud kill which is the reason it begins at the ground each year. You might try to prune the vine back some in the autumn being sure to leave some good current years growth for viable buds the following spring. Fasten the grapes during the summer so you can release them in the fall and drop them onto the ground. Take some straw and cover them or be sure they are banked up with a good layer of snow. The following spring, stand the vine back up and reattach it to the trellis. You should be able to get more grapes. let me know what you think of the idea and I can explain more later on the subject.

 

[Gene45]

Thanks for the comments.

My trellis is a cheap wooden fence I built when the plants were small, and is practically invisible now. Today the trellis is likely held up by the old growth that was not pruned away. The whole thing looks like a hedge.

I'm not enthusiastic about the idea of laying them down and covering , as I have no source of straw and it sounds like a lot of work to clean up.

I'm thinking my best choice is simply to keep it pruned as a hedge, and divert some of the growth into fruit instead of vines and leaves.

We had what we thought was good crop once, and we used a "mineral supplement" which was advertised as "not a fertilizer" . It has not been available again. I don't know why, and can't remember what it was called.

The only extra bit of advice from experienced growers would be what fertilizer and or other mineral supplements would be useful. With the wild growth of leaves and vines, I would guess Nitrogen is not on the list.

The watering system uses hard water, 300 ppm hardness and 3 ppm iron.

 

[grapeman]

It sounds to me like it is not dying back each year like I thought you were saying. It sounds now more like you have not been pruning away enough each year. Fruit comes from one year old wood (bronze or copper color smooth bark) and needs to be exposed to light for flower bud initiation. If the vine is too thick it creates its own shade. It needs to be pruned away about 90% each year. You just leave the trunk and main arms or shoots. From those you need a few buds on short spurs. From those buds you will get a new shoot at each bud. When they have gotten enough light the previous year, you should get a couple clusters from each shoot.

 

[Gene45]

OK. I'll cut it back some more this fall.