Grain Amaranth: How to Grow & Harvest (UK)
On this page
In the UK, grain amaranth goes in the ground early April to early May, and is ready to harvest 90–100 days after planting.
Timing is the decision that matters most in the UK: there are 4 separate regional sowing windows, ranging from early April in Southern England to mid April in Scotland.
The short answer
- Plant
- Early April to early May
- 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
Regional Planting Calendar
| Region | Sow |
|---|---|
| Southern England derived | early April to early May |
| Midlands derived | early April to mid May |
| Northern England derived | mid April to mid May |
| Scotland derived | mid April to late May |
Rows marked derived are interpolated between regions our sources do state, because no source we consulted gives a figure for that region specifically. They are deliberately wider to reflect that uncertainty.
Southern England - detail & sources
DERIVED: no hypochondriacus-specific UK source states a sowing window. Modelled on sister species A. caudatus's RHS-sourced mid-spring direct-sow guidance, adjusted for the earliest UK frost-free window per Met Office (southern/coastal regions' last air frost typically before April ends).
Midlands - detail & sources
DERIVED: interpolated a week later than southern England and a week earlier than northern England, following the same reasoning as the southern England row.
Northern England - detail & sources
DERIVED: modelled on sister species A. caudatus, adjusted later per Met Office's documented later last-frost dates further north.
Scotland - detail & sources
DERIVED: modelled on sister species A. caudatus; Scotland gets the latest sowing window in the UK for this frost-tender species per Met Office's frost-gradient data.
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 |
At a Glance
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. It is a warm-season crop that will not survive frost (RHS), so in the UK start seed under cover in warmth in spring and plant out only once frost risk has passed, or sow outdoors once the soil has warmed to about 18°C (65°F); Purdue gives late May–early June at soil ≥65°F, with best germination at 18–24°C. Space rows about 45–60cm (18–24in) apart (UIC) and thin seedlings so plants stand roughly 30–45cm apart, matching their eventual 0.5–1.5m spread (RHS). |
| 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
Diseases
Pests
Grain Amaranth, Seed to Harvest
Plan your Grain Amaranth planting
When to sow and plant Grain Amaranth depends on your own frost dates. Check the UK vegetable planting calendar. 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.
References
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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.
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States Amaranth = Amaranthus caudatus, common name "Pigweed", cited to an RHS URL. That URL was checked this session and returns empty/dead -- citation hygiene issue, matches Phase 0's general finding about this document. Preserved for provenance of the dispute, not counted as an independent verification source.
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Annual or short-lived perennial. Full sun. Prefers well-drained fertile soil, tolerating clay, loam and sand at acid, neutral or alkaline pH. Propagate from seed or root cuttings. Young leaves have a mild flavour cooked like spinach; seed can be eaten raw or cooked, used as a cereal substitute, or popped like popcorn. CAUTION: avoid eating leaves from plants grown with chemical fertiliser, since the plant concentrates nitrates in the foliage. Wind-pollinated. Aphids may be a problem; no disease specifically named.
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Genus-level cultivation guide; used to supplement species pages lacking their own cultivation block (esp. A. hypochondriacus).
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Short-season field study, the closest published analogue to Prairie conditions: amaranth sown at Prosper, North Dakota in the first week of June; first seed shatter 15 September (1993) and 14 October (1994); harvest before a killing frost was not feasible because of high moisture in the sample; grain yield decreased as harvest was delayed beyond first seed shatter, especially after a killing frost; amaranth should be harvested as soon as possible after a killing frost to reduce yield loss and maximise seed germination; the cooler 1993 season yielded 20-40% of 1994 at the same harvest dates.
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Specifically about vegetable amaranth (A. tricolor), a DIFFERENT species from A. caudatus/cruentus/hypochondriacus. Used only for: (a) confirming caudatus/cruentus/hypochondriacus are the grain-type Amaranthus species, and (b) pest genera (stem weevil, leaf caterpillars) that the source itself sources from CABI as genus-wide. Explicitly NOT used for A.-tricolor-specific growing-condition numbers.
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Addresses grain amaranth production generally (primarily A. hypochondriacus / A. cruentus, the commercial US grain species); not species-disambiguated in the source itself.
14 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
When should I sow grain amaranth in the UK?
In Southern England, from early April. In Scotland, wait until mid April. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.
When do I sow grain amaranth?
Sow early April to late May, at around 18°C for germination.
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
Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.
Get the UK Garden Planner →Instant PDF download · Written for UK growing conditions
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 RHS and Met Office guidance. 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.