advice for re-soiling a grape vine

Question

I took over my allotment in May last year and was lucky enough that it contains a 15 yr old grape vine in a Greenhouse. Last year I left it to do its own thing and just pruned it a bit and thinned out the grapes I got a loverly crop of grapes from it. In the Autumn then after reading various advice I trimmed it back, tidied it (it had been left to its own devices for about 2-3 years) and scraped the surface of the bark back.

I am now intending to re soil it as I don't know the last time the soil in the greenhouse was replaced.

My question, when I re soil should I also mix fertiliser in with the fresh soil directly around the roots, Or should I just mulch and fertilse the top of the soil to prevent risking damaging the roots? what is the best kind of fertiliser to use?

Answer 1

15 years is actually quite young for a grapevine. Since it is not showing any specific signs or symptoms of problems messing with the roots might be counterproductive. Rather perhaps put effort into getting some soil samples analyzed for deficiencies and quality and use that analysis as a guide for supplemental feeding. Well rotted manure or compost might be all that is required. If it ain't broke don't fix it. In another 35 or so years pull out the entire vine with as much root as possible, replace soil entirely and plant new vine. In the meantime prune hard and focus on establishing a base framework to make maximum use of light exposure.

Answer 2

You can re-pot grape vines without problems. I do not agree with Colin's answer. Many plants requirs that one "messes up" with roots, e.g. by cutting part of the roots. Grape vine is one of such kind: old roots will not absorb very well iron, but by messing with roots, you will break some root tips, and so they will generate young rootlets, and so they can get more iron.

Grape vines are not delicate plants, do not worry. Additionally, they are capable to form new roots from steam. nothing to worry.

Also I'm less optimistic then Colin: 15 years is already a mature plant. I doubt it will reach 50 years: modern grape vines are grafted, so with a much shorter lifetime: many will dies between 25 to 40 year. But this depends also on varieties (of both parts): in general the less you cut (and more fruits you let it to ripe), less seasons the plant will survive (check the size difference between rootstock and trunk).