They are found all over the world, and many of the various species of
Amaranths, including some wild species, are mainly regarded as weeds—hence the
“Pigweeds”—Prostrate Pigweed (Mat Amaranth), Spiny Amaranth and Rough
Pigweed or Redroot, and the well known spaghetti western weed Tumbleweed
PLANTING
Propagation: by seed. Dark seeds are sometimes removed before planting as these
tend to produce very big, weedy plants. The seed is very small and is normally sown
direct, by broadcasting, or sometimes in nurseries for transplanting. About 2 kg/ha
of seed is required. Germination is affected by light and with some species only
takes place in the dark.
Pollination: mainly by wind. Both self and cross-pollination occurs—a number of
hybrids are found, formed naturally by cross-pollination between species.
Soil: similar requirements to maize ie best on fertile soils that have adequate P & N.
Spacing: similar to maize; wider spacing for the larger varieties.
GROWTH CONDITIONS
In general, Amaranths grow in similar conditions to maize, though there are species
and varieties that can often be grown at higher altitudes and in colder areas.
Propagation: by seed, normally planted directly into the field (though they can be
transplanted without any problem).
Day length: sensitive to photoperiod in that the timing of flowering depends on the
day length. Most are short day plants, so they tend to bolt early if planted when the
days are shortening. Different varieties have different responses, which can be a
problem if they are introduced to one country or latitude from another.
Growth period: for leaf varieties, several cuttings of leaves can be taken before the
plants set seed. Modern varieties mature quickly, in about 10–12 weeks.
Temperature: Amaranths are mainly a warm season crop.
Rainfall: soil must be moist for sowing; often irrigated in dry spells.
Pests: leaf eating caterpillars and beetles may become a problem, which can be
picked off or controlled with Malathion or Sevin (carbaryl).
Diseases: not normally a problem, though Cercospora leaf spot and White rust may
occur.
YIELD
Seed yields of over 1 MT/ha have been reported in ideal conditions, though normal
yields are only about 200–250 kg/ha, in theory, as they are rarely monocropped.
Some of the many other so-called “Pigweeds”, such as Lambs Quarters, are members
of the Chenopodiaceae family.
Leaves can be continuously harvested for several months, yielding about 10 MT/ha.
(A.albus). Other species are grown as ornamentals, some of which are perennials.