HUH?
So how do you figure 1 inch of water for a grapevine?
Here in Iowa we usually get plenty of water naturally but how do you know how much is an inch when you use a watering can during our infrequent droughts?
Let’s suppose the grapevine is 2 feet by 20 feet, which makes it 40 square feet in area or 5,760 square inches. If this area were to be filled by 1 inch of water it would require 5,760 cubic inches of water.
How many gallons is this?
Use the handy volume converter at
http://www.1728.com/convvol.htm
and you will find out that 5,760 cubic inches equals 3 and a third cubic feet or about 25 gallons.
Wow, did you think it would be that much? (Of course I’m just estimating the size of the grapevine.
Hmmm a 2 foot grapevine huh?
Hell thats a pretty good sized tree.
Presumably you have to cover the root area of the vine to a depth of one inch. The rule of thumb for trees is that the roots extend as far out as the canopy. I’m not sure what the rule is for grapes.
justwannano
I was thinking in terms of the “canopy” (to use Squink’s term).
So, how big do the grapevines grow in the Hawkeye State?
Anyway, one square foot = 144 square inches and a depth of 1 inch of water would equal 144 cubic inches which equals .62 gallons.
So, basically, you’d need .62 gallons of water for every square foot of grapevine provided (as Squink mentioned) that the root area of the vine = the canopy area.
Here’s a gardener’s answer –
A watering can is obviously insufficient.
Set up a sprinkler. Put out a couple of coffee cans at different distances from the sprinkler head. Turn on the sprinkler. Let it run about an hour. Go out and measure the water in the cans. Average those figures. If the average is less than an inch, turn the sprinklers back on. If it’s more than an inch, you’ll know next time how long to run the sprinkler.
Note: Less frequent, deeper watering is better than more fequent, shallow watering – the plants will be better off getting a full inch once a week, rather than a half inch twice a week or a quarter inch every other day. A good soaking lets the water run down deep, to the roots – shallow waterings leave the water at the surface, so the roots come up looking for it.
That ‘rule of thumb’ can only be applied in forest situations, and it is meant to simplify spatial dynamics equations, it’s not real. An individual tree can have roots that extend out over 10 times the area of the drip zone and it is rare to have a tree where the root area isn’t at least twice the canopy area.
The rule of thumb is workable for dynamics equations because in a forest with near continuous canopy every tree’s roots will be occupying space that’s approximately proportional to horizontal canopy area. That’s not to say that every tree isn’t ‘feeding’ under its neighbours canopy but in terms of modelling it often doesn’t usually matter. Somehow this simplification got translated into common folk-lore to the point where people actually believe that the root zone and drip zone are physically the same size, which is almost never the case.
That’s good to know. Now I’ll start really soaking my cherry tree; but that still leaves me wondering about grape vines. How big do their root systems get?
From Growing Grapes in the home garden
by Richard Jauron, Gail Nonnecke,Donald Lewis and Mark Gleason
Grape root systems are extensive. The majority of the roots are in the upper 2 to 5 feet of soil. However roots can penetrate 25 to 40 feet in course, sandy soils.
Not really much info .
This is the same publication that says to water 1 inch per week.
Right now, since I just planted the vines, my root system is contained in the post hole I dug to plant them in. Generally 6 inches in diameter and 10 inches or so deep,depending on the size of the bare root vine.
I’m thinking that I can determine where the roots go by controlling where the moisture is. Basicly train the roots to stay beneath the trellis.