Pedro Ximénez Grapevines 2022-09-30

[2022-08-27] Today I learned how to callus grapevine cuttings, from a very helpful and friendly gentleman at Harris Organic Wines in the Swan Valley. The same helpful and friendly gentleman who very kindly gave me some cuttings from his Pedro Ximenez vines, and talked to me about his vinyard and wine-making process (including, for example, that they make their own organic brandy there, to use in the fortified wines they produce).

Previously, I’ve simply dipped the end of a grapevine cutting into rooting hormone powder and stuck it in a pot, and I’ve had about an 80% strike rate doing that. Apparently, the way you’re meant to do it is a bit different.

First, using clean, sharp secateurs, remove all the bids from the cutting except the top one.

Then completely bury the cutting upside down in clean sand, with 3 – 5 cm of sand over the end. Water in, then cover with black plastic to keep it damp and warm (from the sun falling on the plastic).

Leave it there for 6 weeks; at the end of that time the top bud (buried at the bottom) should be sprouting, and the cutting should be growing roots. Plant the cutting out (trim the roots if necessary), placing about 2/3 of the length of the cutting below ground. Use a dangling wire or string to encourage the shoots to grow up and climb rather than waving around and potentially getting broken off. Water once a month.

It seems counterintuitive (bury the cutting upside down in sand???) but who knows, I may just not understand the reasoning or biology behind it. So half my cuttings are buried upside down in sand, after being appropriately trimmed; the other half have been dipped in rooting hormone powder and stuck in pots to root like a regular cutting. We’ll see how that goes.

[Later – 2022-10-10] Some research in the meantime indicates that the reason for putting the cuttings upsidedown under black plastic is because heat encourages the callusing process, and the ends closer to the black plastic will (in theory) receive more heat. This, however, was not made clear to me in advance, and I didn’t have any black plastic, so I used clear plastic which probably didn’t have quite the same heat-concentrating effect.

I did get some callusing. We opened up the bag and un-buried the cuttings this weekend just passed, and there were a couple with little rootlets as well as definitel calluses on all of them. The rootlets were on the wrong end of some of the cuttings (the ‘top’ based on the direction of growth of the original vine and the way the buds are pointing), but we planted them right way up and knocked off the top-end rootlets as instructed. I guess we’ll see how that goes.

In any case, they’re in the ground now and will hopefully grow. I did put some of the cuttings in regular cutting-growing pots with rooting hormone, though, and they’re leafing out so I will get at least a few vines out of the whole process.

(Apparently the only benefit of the burying and black plastic method is that the cuttings grow roots earlier, so you can plant them out earlier in the year and have them be mroe established and so grow faster – it’s useful for wineries to get vines established as fast as possible.)

On a less happy note, I’ve had to cancel my order with WAVIA due to quarantine & plant health concerns around a grapevine virus found in their source block vines, combined with their general unprofessionalism and lack of communication. Will be attempting to find somewhere else to source vines or cuttings for the other varieties I want.

[Update 2022-11-28] The cuttings that were callused and planted in the ground have shown no signs of life. Half the cuttings i planted normally (rooting hormone powder, and stuck in pots) have leafed out. So my conclusion is that my standard grapevine rooting technique is going to work better for me than the fancy vinyard one. Good to know, I guess.