I am training six grape vines to a cane-pruned VSP/guyot system - golden muscat, jupiter and vanessa. The GM are growing great and produce plenty of shoots for canes and renewal. The other four produce very few, if any, buds on or near the trunk. Two (the jupiters) are in their 4th year and I’m still at what I understand to be the 2nd year stage - that is, I haven’t really been able to extend canes out yet from the trunk (which did reach beyond the top wire by the end of last year). If there are latent buds I just can’t see at the right height, I may get canes this year, but that’s what I thought was going to happen last year, and it didn’t. So I don’t have a lot of hope. Should I cut them back low (like just above…or maybe below…the bottom wire) to encourage growth from the trunk? Or…?
The other two, the vanessa vines, gave me decent canes last year, but no real options for renewal… In this case…do I leave the old canes as though they were cordons, hoping for renewal options from latent buds near the trunk? Or cut them back to trunk and make them start over? I feel like if I leave last year’s canes, the vine won’t be forced to push at/near the trunk…but I’m new at this.
Also - I am growing in NH Zone 5B/6A and have been advised to bring up two trunks on each plant. But I don’t get many buds, if any, forming on or near the crown of the plants. Is there some way to encourage this?
Any ideas of what I could be doing wrong? Underfertilizing? Growing the wrong varieties for my location (the vines came from Double A vineyard in NY 6A, and seem plenty hardy)?
The ground was sodden when I planted the vines (we call it “mud season” here, and some years it can be hard to avoid). I feel the soil may have become quite compacted (despite being sandy loam) when I planted them out. Would it be a terrible idea to aerate the soil a bit with a fork (say, 8-12" deep)?
I’m a little confused by this statement. Did you mean that the buds on the trunk aren’t producing shoots or that there are no buds at all? Each node on a grape cane has at least three buds, so there should be plenty of buds to work with, unless something (cold or frost maybe) killed them. Grapes can’t produce buds from the internodes, however, so if your internode spacing is wide, you will have few area from which shoots can grow.
How thick was the trunk? Anything less than pencil thickness I would cut back near ground level.
By “decent canes last year” do you mean that you had canes that grew in 2023, tied down in 2024, and grew new canes that you need to prune now? Or you have canes that grew in 2024 and you are looking to set up renewals now? For the latter case, once the shoots push from your canes, either a downward pointing shoot coming off the cane close to the trunk or a shoot from the trunk itself become your renewal spur. Your cane for next year would be any well-positioned shoot with decent vigor. Next spring, two shoots should grow from spur, the uppermost one becomes the cane for 2027 and the lower shoot is pruned to two buds to extend the spur. Since the renewal spurs extend upwards gradually over time, they should be at least 4-6 inches below the wire you’re tying your canes to.
No buds visible at all on or near the top of the trunk (yes, at nodes, where older shoots have been previously removed). There may be viable - but latent - buds present that I just can’t see. But I guess (from my pitifully little experience) I wouldn’t expect those latent buds to become active, if not already swelling and visible at this time of year) unless forced (by which I mean pruned back so that the vine had no other options farther up the cane/trunk…I perhaps wrongly assume that the plants are apically dominant, if given the choice).
I’m is zone 7a but this winter temperatures only went down to 7F. My grape plants just started growing last week so you still may get growth as the season progresses.
Are you able to upload a picture? That would help. The latent buds on the trunk and other older parts start growing last. If the primary buds on your canes haven’t really started growing yet, you may need to wait longer. Some varieties naturally don’t push a lot of growth from latent buds. If you have canes, the plant will prioritize the buds on those.
In my opinion, that is too thin to keep for a trunk. I would prune to three buds and restart. However, since you said they’re 4 years old, you may need to fertilize. How much sun are they getting?
Did you plant these as bareroot vines or potted? Grapes do very poorly when planted out with bent or potbound root systems.
The former…sort of: I tied the canes down last year; they grew out in 2023. BUT, the canes I tied down in 2024 didn’t really produce any vigorous shoots near the trunk. The first good shoot that I see as this-year-cane-worthy is 18" from the trunk on one one side of the vine, and there simply isn’t a good shoot from last year’s cane at all on the other side…all far too small and far from trunk. Same on both plants. I think it’s clear I pruned poorly last year (maybe not sever enough? Left too many nodes?)…but I don’t know how to correct the mistake. One thing I do know (now, based on what you say about ideal spur height) is that my plants aren’t (last year or this year, yet) pushing buds low enough. I don’t think my internodes are too long. They just don’t push shoots.
OK, here are photos. You can see I did some pruning already (don’t laugh), but then thought I’d better ask some questions before continuing. You’ll see I cut last year’s cane where there was a shoot closest to the trunk (18" away!), to possibly use the cane and the shoot combined as this year’s cane (that is, extend last year’s cane with last year’s new shoot to become this year’s cane). I have no idea if that’s a really dumb idea or not… One one Vanessa, there is actually a decent shoot at the trunk after all (it’s tied straight up right now…no idea what I was thinking there…basically just that I didn’t know what I was doing…), but maybe it originates too high to be either cane or renewal spur…? The other side of the plant is weak - I’ve tied the only even slightly decent shoot to my guide wire, but it’s pretty small and maybe I should cut it back as a spur instead…? Or…yeah…start over?
Trunks diameters (I took my caliper out there):
-vanessas: .44" near top, .5" near base (the largest of last year’s canes is .34" near trunk)
-smaller vine (jupiter, with no canes): .25" trunk, near top.
They get full sun…well, at least 6-7 hrs in summer. And we have very sunny skies most of the time.
They were bareroot. But went into sodden, possibly compacted soil.
I’m fertilizing with Pro-Gro, which is 5-4-3 or similar. Maybe I need to break out the bigger guns (if so, recommendations on product/quantity/schedule?)
I don’t normally deal with American hybrids which tend to have thinner canes than vinifera varieties, but my guess is that you left a few too many buds based on trunk caliper. That said, most buds along a cane will push regardless if a vine has the capacity for all of them to grow. Some varieties are notorious for concentrating growth only on the first and last shoots of a cane with the middle shoots staying weak and stunted. This can be fixed somewhat by arching the canes so the middle is higher than the ends.
The trunk looks thin enough that you should be able to (carefully) bend that shoot into position as your new cane. That probably won’t solve the problem of have a spur too high up, but if you pull the trunk a few degrees away from vertical while you tie down the cane it might help bring that internode lower. For the other side, I would wait until after budbreak and see if you have shoots emerging from the trunk and prune off the old cane entirely. It’s too early now to see what will push.
For your Jupiter, I would top the trunk below the wire after the buds have pushed and you can see which ones are viable.
I’d say that the basic issue is that those vines lack the vigor to do what you hope they’ll do. Those are very small vines to be 4 years old. Are they really 4 years old? I guess you are in NH which explains much of the vigor/size issue.
You either need more vigor or more patience. Down here I’d have that size after one year.
Yep, planted in spring, 2021. Good thing I don’t know the difference, since I’ve never grown grapes here (or anywhere else)…otherwise, I almost certainly wouldn’t have the patience. They were severely set back (lost all shoots and had to push latent buds) in 2023, when after several (highly unusual) 80+ degree days in mid-April we had a hard freeze in late May. So that year they grew very little… (As you might imagine, grapes weren’t the only thing affected…some of my kiwiberry vines were badly damaged, too, and there were no apricots or peaches to harvest in northern New England that year…even many apples were scarred.)
OK. And on the more vigorous side, how many buds do I leave? (I’m still a bit unclear on the relationship between vigor and number of buds to leave…on the one hand, I would think more buds would allow for more photosynthesis and thus greater future vigor, but if I’m understanding correctly, more buds also puts a strain on the vine and doesn’t allow the plant to size up properly…? This is all assuming no fruit production…)
That’s more or less it. Until leaves reach about 1/3 their mature size, they act as carbohydrate sinks instead of sources. At budbreak, a vine has to use its carbohydrate reserves from the previous year to feed the new growth. Grapevines have a capacity for growth in a given season that is dependent on a bunch of factors like nutrient status, carbohydrate storage, water availability, etc. Let’s say your vine has the capacity to grow 10 feet this year. Those 10 feet can be divided over 10 buds, giving you 10 one foot shoots with thinner caliper, or over 2 buds, giving you 2 thicker five foot shoots. Of course, it’s not quite so simple in real life, but you get the picture. Unlike fruit trees where you’re trying to build a strong framework to carry a heavy load of well-spaced fruit, with grapes the goal of pruning is to control the amount of fruit you get and to renew the fruiting wood.
Flower development in grapes occurs over two years: cluster primordia are formed in the developing buds in leaf axils of the current year’s shoots. The next spring, those primordia develop into individual flower buds. The number of clusters on a given shoot, which accounts for roughly 60% of yield, depends on how much light the bud received and how vigorous the shoot was in the previous year. A shoot that was not able to photosynthesize and store enough carbohydrates will have buds that have fewer or no inflorescences next year.
The reason I stress cane and trunk caliper is because in general, strong shoots only come from strong wood. Unless your vines are in a high-vigor site, weak canes produce weak shoots if you don’t you reduce the number of buds. The weaker your vine, the fewer buds you leave at pruning so that the small pool of carbohydrates the vine was able to store last year go into a smaller number of shoots.
With the size of your vines after 4 years, it’s not really possible for you to leave too few buds. Where I am, I think I get even more growth than @fruitnut. We can get to that size by July on a high-vigor site and have the opposite problem where we need to leave as many shoots as possible to dilute some of the vigor. For your vines, I would wait until budbreak and see where shoots are pushing on your vines then prune accordingly. I wouldn’t consider letting your vines fruit for at least another year, so if you see any clusters, pinch them off while they are small.
My second year Summer Royal in-ground in my greenhouse is out of control. I’m pruning out big shoots and it hasn’t been watered in about 12 months. It’s sucking water from other areas that are getting water. It was in a 15 gallon pot for a year before going in-ground. In a pot one year and it was as big or bigger than the vines under discussion.
I just pruned off about 15 feet total from one of my Errante Noir vines.
It’s the only one that didn’t die last year after planting last spring. It did have a year to establish roots though. Started out about 18 inches tall this spring. It put out a virtual Medusa’s head of shoots. I still have 4 left each 3-6 feet long. Can’t tell which ones will be the thickest this year yet.
I only allocated about 6 total cordon feet in my design. 7 vines on a 45 foot row.
Yeah its just May 1st. It will be fun training once they are producing in the comming years. Hell of a long growing season here…
