Lori Ziemba wrote:I have a Muscat grape that I grew from a cutting in my community garden plot. It's 4 years old. It has never had blossoms on it. It seems healthy otherwise, no bugs or blight or mildew, but it's not very robust. I mean, the stem is only pencil thick. Too cold in summer? Not cold enough in winter? Any ideas? I'm in zone 10b in San Francisco---cool and foggy.
F Agricola wrote:At a glance, I’d say there’s too much competition, fertiliser and root disruption. At four years old, the trunk should be quite substantial and the main leaders organised. They look like one year old cuttings!
When the trunk gets to a height that you want, choose two main leaders and trim off any others.
Since those cuttings are somewhat stunted, they should be okay to transplant – just take a large root-ball.
Preferably not near something that gets that much water, but, if it's deep sandy soil, then it shouldn't be an issue other than grapes usually like a sandy loam – suggest incorporating a lot of organic material like compost and even clay into the holes before planting.
It’s likely a nutrient deficiency caused by leaching through the sand, hence the need to bolster it with organic matter and clay.
I suggest the plot is probably deficient in a whole array of nutrients and trace elements because of it being sandy. Perhaps the best way to grow stuff in that type of soil is to use the ‘lasagne’ method of no-dig gardening. Simply layer compost, manure, lawn clippings, charcoal/ash, very fine gravel (rock minerals), etc in alternating layers, keep it moist and allow to sit for a few weeks to settle; then plant directly into it and mulch.
Bryant RedHawk wrote:I would suggest you get some mycorrhizae and inject it around your grape roots, recent studies are showing that grapes do quite well in bad soil but with mycorrhizae.
The fungi support the root system with extra ability to take in water and nutrients which are provided by bacteria breaking down the rocky substrate (in your case the rocks are very small (sand).
Mulching as others have mentioned will also help the sandy soil by giving it broken down organic materials which will support the microbiome, especially in the rhizosphere.
Bryant RedHawk wrote:I would think that grapes would love cool and foggy weather. The mulch is good but don't mistake fungi in the mulch for mycorrhizae, mycorrhizae are highly specialized fungi that only live a. wrapped around roots so tightly that they make the root look fuzzy or b. inside the cells of the root, where we don't see them unless we slice the root and put a slide under 2000x + magnification.
It sounds to me like there is perhaps some type of compaction problem going on. with continued mulch and maybe some compost added to the mulch the soil will become better conditioned.
The best grapes I ever ate were wine grapes from a very small winery in up state California, the vines get cool, foggy breezes every day from the ocean not far away and the soil is not soil it is rocks, only rocks for 3 feet down.
The Vinter told me that he inoculates all new vines with mycorrhizae as they are planted, then they water them until it is apparent they have settled in. Once that occurs, they might get watered if there is no rain for over 40 days, otherwise only that cool fog gives them moisture.