Researchers at Tokyo University report daily fluctuations in the mineral content of spinach leaves. Nitrogen, phosphorus, potassium, and magnesium levels were found to start dropping after sunrise, hit a minimum in late afternoon, then increase to a maximum at dawn.
PHOTO: MOTHER EARTH NEWS STAFF
Greg and Pat Williams, expert gardeners, share tips and ways to utilize new gardening research for seasonal gardening.
Special Yield-Boosting Treatments
Recently, we've collected quite a few ideas concerning
doing "strange" things to vegetable seeds and seedlings to
try to increase yields. All of these suggestions are based
on research reports from professional
horticulturists—but that's no guarantee that they'll
work for you. In fact, we're hoping that readers of THE
MOTHER EARTH NEWS will experiment with these techniques and
let us know their results! (Just remember to grow a few
untreated "control" plants to compare to your experimental
Russian scientists have seen yield increases of up to 88%
after soaking the seeds of some tomato varieties in a
6.5 % solution of skimmed milk. Another
tomato seed treatment (reported by Egyptian researchers)
for boosting yields is to heat air-dried seeds for two
hours at 140 degrees Fahrenheit: Apparently, the heat changes the
proportions of natural growth regulators in the plants.
A Netherlands experimenter has found that thinning peppers
to leave only a few fruits at the initial fruit-setting
stage increases yields and average fruit size. Canadian
researchers reported large yield increases for cowpeas that
were "beheaded" between the fourth and fifth leaves on the
main stem when the fifth leaf reached full size. The
decapitation also made the plants more compact. (Might this
technique work with soybeans or green beans?) Similarly,
Cornell University horticulturists found that removing the
growing tip from a tomato plant when it has four or five
leaves delays first flowering two to five days, but then
creates simultaneous flowering of several branch clusters
and hence higher "second-earliest" yields.
Research indicates that if you're growing your own
transplants, you should not skimp on container
size: Many vegetables produce larger yields when started in
roomier pots. And several studies have shown beneficial
results from watering just-transplanted vegetables with
seaweed extracts . . . which seem to help minimize
Plant growth regulators added to seeds can also sometimes
have positive effects. Researchers in India reported that
soaking onion seeds in a solution of NAAm, or
naphthaleneacetamide, at a concentration of 20 parts per
million for eight hours prior to planting boosted onion
yields by nearly 60%. Soaking the seeds in a gibberellic
acid solution (7.5 parts per million) increased yields by
There seems to be no end to the experiments you can do with
seeds and seedlings!
Seasonal Gardening Research Briefs
Harvest spinach at dawn? Researchers at Tokyo University
report daily fluctuations in the mineral content of spinach
leaves. Nitrogen, phosphorus, potassium, and magnesium
levels were found to start dropping after sunrise, hit a
minimum in late afternoon, then increase to a maximum at
dawn. So if you want the most minerals possible from your
spinach, you'll have to get up early!
Rx for exposed tree roots. Recent experiments in England-on
birch and ash trees-suggest that water losses from bare-rooted trees can be
excessive if the roots are left exposed for a couple of hours. Drying for a few
minutes, though, is unlikely to be damaging, so don't worry about keeping the
roots damp every second. What about roots that arrive in the mail already dry?
The English research suggests that soaking can be beneficial — at least in some
instances — and does no harm in any case.
Water your lawn trimmer line. A professional lawn care
company has found that the nylon line used in rotary lawn trimmers lasts about
twice as long if it's stored in water before being put on the trimmers. (The
water makes the line less brittle.) The treatment is supposed to be most
effective when temperatures are high.
Don't overwater the sweet potatoes. If you grow sweet
potatoes in a dry climate, cut back on irrigation for one month, beginning
about a month after planting. According to Tennessee State
drought stress during this period results in reduced top growth and bigger root
yields. Drought stress imposed late in the season, though, reduces root yields.
Green up your grass with iron. Horticulturists at the
University of Illinois, Urbana-Champaign have found that
foliar sprays of iron sulfate or iron chelate can enhance the color of Kentucky
bluegrass without overstimulating growth the way added nitrogen does. An
application of one pound iron per acre (about one-third ounce per 1,000 square
feet) is recommended. Enhanced color lasts from a few weeks in cool wet weather
to several months in cool dry weather.