GardenBanter.co.uk - View Single Post

William L. Rose · 12-08-2006, 05:57 PM posted to rec.gardens.edible

In article . com,
"simy1" wrote:

wrote:
Hi, Everybody,

I have read that tomatoes should be placed in a different area
each year, due to the risk of diseases building up in one spot of
soil.

Apparantly, this also applies to potatoes. Are they
interchangeable (meaning that I shouldn't put tomatoes in the
spot where last years potatoes were)?

So I am wondering how many different areas are needed? Meaning,
How many seasons/years does a previously used spot need, before
it is safe to put tomatoes there again?

If I rotated around three areas, would that be enough? Or four?

It depends on soil, moisture, high and low temperatures. It depends on
whether you pull the plants after the season or leave the roots in the
ground. If your soil is sandy and freezes in the winter, you can rotate
a lot less than if you have a soil that stays moist through the year.
It depends on the general health of the soil (compost, microfauna,
etc.). It depends on the disease. Cabbage clubroot can persist 15
years.

Currently, I have a 1.5 years rotation in my tomatoes (that is, I
rotate some spots, and I reuse some spots) and I see no diseases. I do
the short rotation because I want the best possible access to the
cages, other pick-once vegetables occupy the more remote parts of the
garden. I use drip irrigation, mulch, and I make sure that wayward
branches are pulled into the cage as soon as possible, all practices
that cut down on disease. My soil is very sandy and, if not mulched,
is dry at the surface within an hour of a rainstorm. I only saw a few
diseased tomatoes a few years back, all Costoluto heirlooms, planted in
a spot that had never grown tomatoes before. I have since learned that
this particular heirloom has become very disease-prone in the last
decade or so. The other heirlooms thrive.

So, in regard to your problem, you will have to see what works in your
case. There are other considerations that can shorten your rotation. Is
this spot more limed than another? Is this spot sunnier? Then
lime-loving and sun-loving veggies will go there more often. I have two
spots in my garden where the same veggies are grown every year. The
rest I rotate. Generally, in rotation you try to have plants as
unrelated as possible so that diseases can not thrive on successive
years. Potatoes and tomatoes are both solanaceae, and likewise you
should not plant cabbage and tatsoi (brassica and mustard) in the same
place.

On the other hand, being bestowed with a profound ignorance of growing
tomatoes, I have grown tomatoes in the same spot in amended clay soil,
for eight years and I can't discern any difference in vigor, or fruit.
- Bill