Amaranthus caudatus L.

Annual, monoecious, robust herb to 2 m; stems often red; indument of stems, young leaves and inflorescence-axes pubescent with tangled white hairs. Petiole to 13 cm long, shorter than to as long as blade; blade green to red or red-tinged, lanceolate, elliptical, ovate or rhomboid-ovate, (2.5-)6-20 x (1-)2-8 cm, apex obtuse or acute, often of much smaller size just below inflorescence, glabrous or somewhat puberulent below. Inflorescence of small axillary clusters and massive, lax, tail-like (thus, "caudatus") terminal panicles or spikes to 30(-50) cm long; bracts and bracteoles deltoid-ovate, lanceolate or lance-acuminate, 3.5 mm long, shorter than tepals, midvein excurrent, rigid arista at apex. Flowers green, white or reddish, at least some flowers with tepals recurved at apex at maturity. Male flowers interspersed throughout inflorescence; tepals 5, ovate to oblong, 2.5-3.2 mm long, acute; stamens 5. Female flowers more numerous; tepals 5, outer one tepal elliptical or oblanceolate, 1.5-2.8 mm long, acute, inner 4 tepals somewhat shorter than outer one, spathulate or oblong-spathulate, recurved; styles 3, erect. Utricles circumscissile, ovoid-globose, 2.0-2.5 mm, as long as or exceeding perianth, smooth or rugulose; seed subspherical or lenticular, 0.8-1.5 mm, variable in color, white, tawny, reddish-brown or black, dull or lustrous.

A tropical plant. It can grow in warm temperate places. It cannot tolerate frost. Plants do best under high light, warm conditions and dry conditions. They need a well drained soil. Some varieties can tolerate pH up to 8.5 and there is some salt tolerance. It can grow in arid places. In the Andes it grows between 500-3,000 m above sea level. In PNG it grows best between 1,600-2,400 m above sea level. It suits hardiness zones 8-11.

The leaves and young plant are eaten cooked. They are also used in stir fries and added to soups. The seeds are ground into flour and used to make bread. CAUTION: This plant can accumulate nitrates if grown with high nitrogen inorganic fertilisers and these are poisonous.

Plants can be grown from seed if the soil is warm. Seeds are small and grow easily. Cuttings of growing plants root easily. Amaranths are mostly grown from seeds. The seeds are collected from a mature dry seed head of an old plant. These dry flower stalks are stored and then the flowers rubbed between the hands over the garden site. Collecting the seeds is fairly easy by banging flower heads on a mat or piece of cloth then the rubbish can be blown out of this mixture by dropping it and blowing gently as it falls. The very small seeds of these plants are scattered over the ashes or fine soil in fertile ground. Some types are self sown. Amaranthus seeds are very small. A thousand seeds weigh about 0.3 g. It is very difficult to sow such small seeds evenly over the ground. So there are a few different methods you can use to try and get the plants well spaced. One way is to mix the seeds with some sand and then when you sprinkle this along a row it will only contain a few seeds among the sand. The other way is to throw the seeds over a small plot of ground which will be a nursery. After 2 or 3 weeks the seedlings can be transplanted into the garden bed where they are to grow. If the seeds are just scattered over the garden, the small seedlings can be thinned out and either eaten of transplanted to a different spot. Seedlings are transplanted when about 5-7 cm tall. Plants can be harvested when small by thinning out and either transplanted or eaten cooked. Plants can be harvested whole or have top leaves harvested several times. Harvesting begins after 4-7 weeks and can continue over 2 months. A spacing of about 8 cm x 8 cm is used if the plants are to be harvested by pulling up the whole plant. If the harvesting is to be done by picking off the top leaves, a wider spacing is normally used. When the tops are picked out 3 or 4 times over the life of the one plant, a spacing about 30 cm x 30 cm is used. As far as producing a large amount of food is concerned, the spacing is not very important. Having between 200 and 1,000 plants per square metre gives about the same total amount of food. The main thing that varies is the size of the leaves. Mostly people like larger leaves so a wider spacing of 8 cm to 10 cm for plants to be pulled out is suitable. For plants to be harvested by picking out the tops, they can be picked down to about 15 cm high. Picking lower makes the plant flower later, but it also recovers more slowly from picking. Amaranths grow quickly. Seedlings come up above the ground in 3 to 5 days. They are 5 to 7 cm high and big enough for transplanting after about 20 days. The plants can be pulled out and used after 6 weeks. If they are harvested by picking out the tops, this can be started at 5 to 7 weeks and continued 3 or 4 times over the next 2 months. Amaranths eventually stop producing leaves and grow flowers. Flowering occurs after about 3 months and seed can be recollected about a month later. Amaranths are called day-length neutral plants because they still produce flowers at about the same stage, irrespective of whether there are many or few hours of daylight. Because flowering stops harvesting of leaves, it is a problem, but there does not seem to be any easy way of slowing down flowering. Flowering can be delayed a little by picking out the tops down to a lower level. Also it is made a little later if plants are grown in the shade. But lower picking and growing in the shade mean the plants produce less food, so there is no point. Plants need to be harvested and used when they are ready. If plants are left growing the amount of harvestable leaf gets less and the quality gets poorer. Nitrogen deficiency shows as the oldest leaves near the bottom of the plant going yellow. This is because the plant needs more nitrogen to grow more new leaves at the top and there is not enough nitrogen in the soil for it to get it from there. So it reuses the nitrogen it used in the oldest leaves. These leaves therefore go yellow. Potassium deficiency shows as the edges of the oldest leaves going yellow. These shortages of nutrients could be corrected by adding some nitrogen or potash fertiliser but it is most likely too late for the current crop.