GardenBanter.co.uk - View Single Post - How much triple super phosphate should i apply around established fruit trees?

David E. Ross · 09-10-2007, 06:58 PM posted to rec.gardens

On 10/8/2007 3:32 PM, wrote:
I have some triple super phosphate i want to use around my
established fruit trees to help them harden off for the winter. There
aren't any application rates mentioned on the bag so i don't know how
much to use. Most fertilizer app. rates are calculated by using x
amount based on the diameter of the trunk measured about 2 feet above
the soil line,but not sure if this also applies to triple super
phosphate. I live in Southern Calif. where soils are on the alkaline
side. How much can i use w/o over doing it? Thanks.

You don't really need phosphorus for winter hardening.

If fruit production seems reduced, it could be that phosphorus in the
root zone has been depleated. Phosphorus does not leach through the
soil, so applying on the surface in anticipation of winter rain won't
work. (In any case, it seems that there won't be any appreciable rain
this winter.) Instead, the phosphorus must be injected into the root
zone. For my fruit trees, I take a 2-foot length of steel rebar and
poke holes in a circle just inside the "drip zone", the area where rain
would drip from the outermost branches. Then, with a funnel, I fill the
holes with super-phosphate.

Citrus requires more than merely nitrogen. They require an acidic
fertilizer with iron and zinc. Most commercial citrus foods are acidic
and contain iron but lack zinc. I have an old sack of zinc sulfate that
I use, applying only a small amount to each tree. Frequent (twice a
month) light feeding from the end of March to the beginning of September
is better than only one or two heavy feedings in the spring. ]

Don't feed later than two months before the first expected frost;
feeding promotes tender new growth that will be killed by frost. This
is a good rule for all subtropical fruits, not just citrus.

I'm not familiar with the care for your other fruit trees. However,
plums require care similar to peaches but with less pruning. My peach
tree gets a spring feeding, using generic lawn food broadcast in its
drip zone.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening pages at http://www.rossde.com/garden/