How to Grow Grain Amaranth
On this page
Grain amaranth is a frost-tender, warm-season crop: seed needs soil warmed to at least 18°C to germinate well (best germination is 18–24°C), and plants will not survive frost, so sowing has to wait until the soil is warm and all frost risk has passed.
The short answer
- Ready in
- 90–100 days
- Site
- soil pH 6.5–7.5
- Biggest risk
- Damping-off
Core growing advice on this page is checked against named horticultural sources — see References.
Grain Amaranth (Amaranthus hypochondriacus)
Also known as: Amaranth, Prince's feather · 14 sources cited · Verified
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 6.5 - 7.5 |
| Germination temp | 18°C |
| Optimal growing temp | 19-23°C |
| Minimum survivable temp | 0°C |
| Time to harvest | 90-100 days |
| Soil texture | Loam preferred; adapted to a range of soils per genus-level RHS guidance |
| Drainage | Moist, well-drained, humus-rich |
| Lifecycle | Annual. |
| Edible parts | seeds, leaves |
| Documented problems | 4 diseases, 3 pests |
At a Glance
Diseases
Pests
Soil & Growing Conditions
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Establishment | 0 | Grain amaranth is grown from its very small seed. Sow no more than 0.5–1cm (¼–½in) deep — Purdue NewCROP and UIC Heritage Garden both say no more than ¼–½in — onto a firm, warm, moist surface, sowing thinly and barely covering it. |
| Vegetative Growth | 3 | Plants grow quickly into upright, broad-leaved bushes typically 1.5–2m (5–7ft) tall (RHS lists 1–1.5m+ depending on variety). Grow in full sun on a warm, sheltered site in moderately fertile, humus-rich, well-drained soil — RHS notes that adding organic matter promotes strong growth, and that plants dislike cold, wet soils and shade. Keep young plants weed-free while they establish and water in dry spells to keep growth steady. Only moderate nitrogen is needed: Purdue/Wisconsin scale fertiliser to soil organic matter (more N on poor soils, less on rich), and excess nitrogen encourages soft leafy growth at the expense of grain. |
| Flowering | 6 | From midsummer to early autumn the plants produce dense, erect or drooping catkin-like flower panicles in shades of green, gold, red or purple (RHS). The seed heads are large — UIC notes a single head can hold up to about 60,000 tiny seeds. Keep plants adequately spaced and weed-free for good air circulation, which RHS notes helps prevent foliar disease at this stage. |
| Fruit Development | 7 | After flowering the panicles fill with grain — Amaranthus hypochondriacus is one of the principal grain amaranth species. Seed typically ripens about three months (roughly 90–100 days) from sowing (UIC; RHS). Watch for the seed heads to change colour and begin to dry down as the grain matures. |
| Ripening / Harvest | 8 | Harvest once the seed heads are dry and the grain threshes freely: gently but briskly rub or shake a flower head between your hands and see if the seeds fall readily (UIC). Work in dry weather — commercially the crop is cut in dry weather three to seven days after the first frost, once the heads have dried (UIC; Purdue: a killing frost followed by a week of good drying weather). Cut the heads, dry them fully, then rub out the seed and winnow off the chaff. Store the cleaned grain dry — Purdue gives about 11% moisture maximum — in an airtight container. |
| Senescence / Dormancy | 9 | Grown as a warm-season annual, the plant dies back after seeding or is killed by the first hard frost. Save some clean, dry seed for the following year; note that plants self-seed readily if the heads are left to shatter in the garden. |
Harvest & Storage
Plan your Grain Amaranth planting
Timing for Grain Amaranth follows soil temperature and frost, not the calendar date. The Global vegetable planting calendar explains the method. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.
Growing Grain Amaranth in another region
Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.
Sources
-
Field survey of 43 peri-urban Amaranthus farms; identifies anthracnose (Colletotrichum), wet rot (Choanephora cucurbitarum), wilting/damping-off (Fusarium, associated genera), and stem canker (Phoma/Alternaria) as the major fungal diseases.
These 6 sources are specific to this region. The full list of 14 sources behind this guide (African Journal of Agricultural Research (peer-reviewed; Appiah-Kubi et al. 2022, DOI 10.5897/AJAR2022.15985), Canadian Journal of Botany, FAO EcoCrop and others) is in the references of our UK guide to grain amaranth; they describe the plant itself, which is the same wherever it grows.
Frequently Asked Questions
How long does grain amaranth take to grow?
Typically 90–100 days, depending on cultivar and growing conditions.
What soil pH does grain amaranth need?
A pH of about 6.5–7.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect grain amaranth?
Our data links 4 diseases and 3 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.
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How this guide is put together
The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against international horticultural research and extension sources. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.
Last verified 2026-09-03
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Keep going
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.