A follow-up question:
I’d quite like to take a cutting or two and plant them out in the polytunnel, where they might be more successful, so any advice on the feasibility of this would be appreciated too. Ideally they’d be trained to run the length of it overhead, supported on the cross-braces.
Do you happen to know the variety? That can impact how to prune and whether or not you need to spray.
It looks like a pure vinifera variety, so you will need to spray with something that controls downy and powdery mildew.
In my climate, I would pick one of the two longest canes, tie it down horizontally about 3 feet off the ground, remove the other canes, and train the new shoots vertically up the trellis. Those would be the fruit bearing shoots and get renewed every year.
In your climate, I think this would be the best way to ensure it gets enough warmth to ripen the fruit. Dormant cuttings taken from the current-year’s growth in winter involve the least amount of work. If you want to get started this growing season, green shoots will root as well if taken once the new growth hardens off a bit. You can also bend one of the canes down and bury a section. The buried portion will root by the end of summer, and you can dig it up and replant in the polytunnel.
If it were mine I would let them grow just as you have them now this season, produce this year’s fruits. (I am assuming this side of the greenhouse is your South side.)
Then early next spring before bud swell, I would lay the longer left leader down about 2-3’ off the ground and tie it in that position (parallel) to the ground. Cut back each lateral on that leader to 1 or 2 buds.
Remove all other growth and the other leader entirely. Use the cuttings to root for more plants.
This configuration will give you a standard cordon that spans your trellis where each year you can train each shoot to a vertical growth up to the height of the greenhouse where you top each one to force growth into fruit production. Thereafter each year you need to only cut back each vertical to 1 or 2 nodes to repeat each growth cycle. In your latitude you need to maximize southern exposure to the fruit, so after your vines set fruit, remove enough foliage that covers the fruit so sunlight can get to it to prevent disease and ripen the fruit. If I am wrong about the orientation, you may need to use a different side of the greenhouse to get full year sun exposure! The best vine pruning book I can recommend to others is this one: Yes, “From Vines to Wines, 5th Edition” is available as an ebook.You can purchase it from various retailers, including Barnes & Noble and Amazon, Hachette Book Group and eBooks.com.
I’ve also applied some fertiliser to the base, and will spray for mildew when the first flowers open, which is what my book says to do. Does that sound ok?
I’m not sure you have room for two tiers of shoots on that trellis unless you train the shoots on the upper cane onto the greenhouse roof. You don’t want them to droop down over the lower tier since that will reduce air flow and light penetration. You can wait and see how things develop and prune accordingly in winter. Your vine may be a little young to be leaving so many shoots.
From a mostly aesthetic standpoint, I would bring that lower cane a little closer to the trellis post like you did with the upper cane this winter so that there is less of a gradual slope upwards. That way all of your fruiting shoots start at the same level.
In my area I would be applying the first spray when shoots are about the length of yours, but it’s much warmer here, and I only have powdery mildew to deal with. Unless you see obvious signs of disease I don’t think it’ll hurt to follow your book’s recommendations.
I have never fertilized my grapes over a 20 year period, the only nitrogen they get is from that produced naturally by the clover growing around the base. Your vine looks healthy, advise to hold on fertilizing, you can mulch them with wood chips which over time will breakdown into natural organic nutrients, may be the best way to add nutrients.
Ok, cheers. I could easily extend the trellis up a bit, if needed.
I was a bit worried, when tying the canes in, about how flexible they were. They started making cracking noises. I’ll have another go at the lower cane as suggested.
Re: fertiliser/mulch - noted, thanks. Do you think spent brewing grains (malted barley) would make a good mulch? I brew quite a lot of beer, so have lots.
Your vine looks pretty vigorous. My thought is that those canes are going to be growing on the ground by late summer, esp the lower tier. I’ve tried the two tier system and the lower one is a waste of effort. All my grapes have required removing fruit clusters even when there’s just the top cane.
You’ll learn this year and can adjust for next summer. You will probably need more support my mid summer to keep canes off the ground.
No need to move it now. You might damage the new shoots. You can wait until winter if you decide to keep the lower cane. The cracking is just the outer bark and usually not a sign of the actual cane breaking. You can “warm up” a cane by gently bending small sections at a time back and forth to avoid breakage.
That’s it in a nutshell. I’ve seen plenty of grape vines (recent trip to SoCal), but never really looked at them. I’ll know what to expect next time around, so, a light touch this year suits me just fine.
How about I re-tie that lower cane to one of the bottom two tiers of the trellis, prune the upper cane back to 4-5 shoots, harvest these for cuttings later on (when?), then prune the upper cane out entirely?
That would solve the awkward bend in the lower cane, as well as the issue with too many shoots mentioned above, and provide some cuttings.
Yes, in a big lump they do (‘sour mash’, I guess), but they seem to be ok spread in a 2” layer, say, around strawberries. These are polytunnel plants so get watered every day; maybe that washes the sourness out. For the first few days after spreading, my wife does complain that the tunnel smells of beer!
I like your plan, but would wait for early next spring while still dormant to implement it. Then any cuttings can be readily rooted. Tie the lower cordon down low to give you the ability to tie the new shoots up vertically to trellis for best sun exposure. Cutting should be at least 3 nodes long, bury in a sunny location with only the top bud above soil line.
Dennis
Kent, Wa
I don’t know how it is in the East, but here in the Pacific Northwest, grapevines only bleed during the early spring when they first start growing. After the flower buds form, there’s no bleeding. That’s when I do a lot of my pruning because I remove any growth (green or old) that is not producing fruit and is not useful for future cropping.
The vine seems to be growing nicely, and the first trusses have appeared. For the upper cane, I’ve snipped the laterals back to two leaves beyond the first truss. These will be harvested for cuttings later on.
A landscaper friend has suggested training a cane into the greenhouse; that way, it will be warmer but still get rainwater at the base.
I wondered what your thoughts would be on a new plan:
For the lower cane, train that vigorous lateral (arrowed) up to follow the yellow line, limiting the other laterals to 2-3 trusses. At pruning time, cut at red line. Next year, treat as a cordon, with laterals indicated in blue. Alternatively, when dormant, just bend the whole thing to follow the yellow line.
Upper cane, harvest cuttings at the right time. Then poke as much as possible through a hole in the base of the greenhouse, then gradually train to the middle of the back (right-hand) wall, then eventually up and over the top.
All this would help move the vine to the right, and stop it from shading the tomatoes which are planted inside, the sun coming predominantly from the left of the picture.
