Rain – What Rain
If it rains between November and March we don’t need to irrigate in the winter. This year (2017-18) rainfall as been abysmal – with the only month getting some – but still way less then normal was January where we had about 2 inches in one storm. We’ve had a tiny bit (.25 inches or less) in another storm but it essentially doesn’t count.
Grapes don’t need a lot of water in the winter, but the roots are susceptible to cold injury. Cold injury will occur if low temperatures get into the teens, with some rootstocks being much more susceptible then other. In my experience 101-14 is especially susceptible.
One thing that can really help with cold tolerance is adequate amounts of water in the top 2 feet of the soil. This isn’t required to satisfy evapotranspiration requirements but more to mediate the fluctuations in soil temperatures. That is, wet soils temperatures do not change as much as do dry soils. What this really means is that on really cold nights, the temperature at the root depth in the soil will not be as cold as the air temperature.
The cold temperature effect is complex and has to do with hormones produced in the roots just before bud break and these effect the “pushing” of buds along cordons. In general, the hormones that encourage bud break are reduced and the number of buds that push – and produce clusters (yield) is reduced
My recommendation is that any month were the rainfall does not exceed 1 in, that WINTER irrigation be applied at about 12-24 gallons per vine. The exact amount depends on rootstock, soil, and current water content on the root zone (one of the reasons to invest in soil moisture monitoring sensors).
IGGPRA elections for 5 new board members will be conducted via email very soon as well as at the member annual meeting on February 16, 2018. The meeting will coincide with our annual spaghetti western mixer and is the only event that is for members only. Visit the website on 2/1/18 to see candidates and their bio’s. You will also receive a ballot by regular mail in the first few days of February
Central Coast Party Helpers is a GOLD associate member and they help out at all of our mixer events. They are fantastic and if you ever have a party or event you need help with I highly recommend them. They are having an Open House this Wednesday January 31, 2018 between 5 and 7 pm at their new location at 503 13th Street in Paso Robles.
Check out their website www.centralcoastpartyhelpers.com