Amaranth microgreens are one of the most visually striking crops you can grow on a windowsill or under a grow light. The red garnet variety in particular produces stems of vivid magenta and leaves of deep burgundy that look almost too good to eat. Yet for all their drama, they are genuinely straightforward to grow — provided you understand a handful of quirks around their tiny seeds and their need for good light to express that colour. Whether you are new to growing microgreens at home or looking to expand beyond the standard varieties, amaranth rewards the small amount of extra care it requires with flavour, nutrition, and a garnish that genuinely elevates a plate.
What Are Amaranth Microgreens?
Amaranth (Amaranthus spp.) is an ancient grain and leafy vegetable crop grown across South America, Africa, and Asia for thousands of years. As a microgreen, it is harvested at the seedling stage — typically when the first true leaves have just emerged or are beginning to unfurl, somewhere between 10 and 14 days after sowing.
The most popular variety for microgreens is Red Garnet amaranth (Amaranthus tricolor ‘Red Garnet’). This cultivar is grown specifically for its intense colouration: the seed leaves (cotyledons) and early true leaves are a rich burgundy-red, while the hypocotyl — the stem between the soil and the leaves — can range from pale pink to vivid magenta depending on light exposure. Other varieties include Golden Giant, which produces yellow-green growth, and varieties selected from grain amaranth such as Amaranthus cruentus, which tend toward green with red tinges. For the most visually striking results, Red Garnet is the go-to choice.
Nutritionally, amaranth microgreens are a notable source of vitamins C, K, and E, as well as the minerals iron, calcium, and potassium. Like other microgreens, they concentrate nutrients relative to their size, though the exact values vary with growing conditions and seed batch. They also contain lysine — an amino acid that is relatively scarce in many plant foods — which has historically made amaranth grain significant in vegetarian diets.
What You Will Need
The equipment is minimal and familiar if you have already explored how to grow microgreens. You will need:
- Two trays. One with drainage holes for the growing medium; one solid tray underneath to catch water. A standard 1020 tray (approximately 25 cm × 50 cm) or a smaller half-tray both work.
- Growing medium. A 2.5 to 3 cm layer of coir, a purpose-made microgreens mix, or a peat-free seedling compost. Avoid heavy potting compost — it retains too much moisture.
- Amaranth seeds. Buy seeds sold for microgreens or sprouting; these are untreated. Grain seed for farming may carry fungicide coatings.
- A fine-mesh shaker. A repurposed spice jar with holes punched in the lid works well. Because the seeds are tiny, this makes even sowing much easier.
- A spray bottle. A fine-mist bottle lets you water gently during germination without displacing seeds.
- A blackout cover. An opaque lid or inverted tray keeps humidity high and light out during the germination phase.
- A bright window or grow light. Adequate light is non-negotiable for good colour development in red garnet amaranth.
Handling the Very Small Seeds
Amaranth seeds are tiny — comparable to poppy seeds — and this is where most beginners have their first frustrating moment. Pour them straight from the packet and they clump at one end, drift in any air movement, and are nearly impossible to redistribute once wet. A few practical techniques make the job straightforward:
- Do not soak before sowing. Many larger microgreen seeds benefit from a soaking period, but amaranth seeds are so small that soaking causes them to clump irreversibly. Sow them completely dry.
- Use a fine-mesh shaker. Transfer your seeds to a small jar with a perforated lid, or fold a piece of paper into a cone and tap gently over the tray. The aim is an even, light dusting — not a dense carpet.
- Sow in two passes. Divide your seed quantity in half. Sow the first half moving the shaker in one direction (left to right), then sow the second half moving in the opposite direction (front to back). This cross-hatching technique fills in gaps and reduces heavy patches.
- Avoid pressing the seeds in. Because of their tiny size, amaranth seeds need to sit on the surface or with only the lightest covering of medium. Pressing them deeply into the soil delays germination and can prevent the seedling from emerging cleanly.
- Work in still air. Even a light draught from an open window or a fan can scatter seeds across the room. Close doors and windows before opening the seed packet.
Sowing Density
Because amaranth seeds are so light, it is easy to under-sow (patchy tray, too much bare medium) or over-sow (crowded stems, poor air circulation, mould risk). A good starting point for a standard 1020 tray is approximately 25 to 30 grams of dry seed; scale to 12 to 15 grams for a half-tray. This produces a moderately dense planting — close enough for the stems to support one another, with enough airflow between them to stay healthy.
If in doubt, err lighter. A somewhat sparse tray of healthy, well-coloured amaranth is more useful than a dense tray that develops damping-off halfway through. You can refine density over successive grows once you know how the seeds behave in your specific conditions.
Germination and the Blackout Phase
Once sown, mist the surface gently — the medium should be moist but not waterlogged. Place the blackout cover on top to hold humidity and create the slightly elevated warmth amaranth prefers. The ideal germination temperature is 20°C to 25°C (68°F to 77°F); below 18°C (64°F) germination slows noticeably.
Check the tray once a day and mist if the surface looks dry. The first shoots should appear within 3 to 5 days. Once 70 to 80 per cent of seeds have germinated — a tray covered in tiny green or reddish shoots — remove the blackout cover and move to the light phase.
Light: the Key to Vivid Magenta Colour
This is the single most important factor in producing the striking colour that makes red garnet amaranth so desirable. The intense magenta and pink pigmentation comes from betalains — a class of water-soluble pigments found in amaranth and a handful of other plants, including beetroot. Betalain synthesis is stimulated by light exposure. Without adequate light, even a red garnet variety will produce pale green or yellowish stems.
If you are growing on a windowsill, a south-facing window in summer can provide enough direct or bright indirect light to develop good colour, provided the tray receives at least four to six hours of direct sun or eight or more hours of bright indirect light per day. North-facing or partially obstructed windows are rarely sufficient for strong colour, though the microgreens will still grow and taste perfectly good.
A full-spectrum LED grow light gives you much more consistent results regardless of season or window orientation. Position the light 20 to 30 cm above the tray and run it for 14 to 16 hours per day. Within 24 to 48 hours of moving the tray from blackout to a well-lit position, you should see the stems begin to flush pink and deepen in colour over the following days.
One useful technique: after removing the blackout cover, do not rotate the tray for the first 24 hours. Let the seedlings begin to orient themselves toward the light source. Then, from day two onwards, rotate the tray 180 degrees once a day to prevent the seedlings from leaning too far in one direction.
Watering Amaranth Microgreens
The combination of small stems and relatively dense sowing means surface moisture can linger and invite mould, so watering technique matters.
After the germination phase, switch to bottom watering: pour a small amount of water into the solid catch tray and allow the medium to absorb it from below over 20 to 30 minutes, then drain any that remains. This keeps the surface drier where the stem bases sit. In the first few days after the blackout cover comes off — while stems are still short — mist the surface lightly once a day until the seedlings reach around 3 to 4 cm.
- Never leave the tray sitting in standing water for more than 30 minutes.
- Let the surface of the medium dry slightly between waterings — if it feels damp to the touch, wait another day.
- Water in the morning so any surface moisture evaporates during the light period.
- Keep air moving around the tray; a small fan on a low setting prevents the stagnant humidity that mould thrives in.
- Do not add fertiliser. Amaranth microgreens take everything they need from the seed and a quality growing medium.
When and How to Harvest
Amaranth microgreens are ready to harvest when the first true leaves are just beginning to appear beyond the seed leaves (cotyledons), or when the cotyledons themselves are fully open and the stem has reached 5 to 8 cm in height. This typically falls between day 10 and day 14 from sowing, though temperature and light levels will affect the timeline in your specific conditions.
Harvest in the morning after the lights have been on for an hour or so. At this point, the cells are turgid with moisture and the greens are at their crispest. Use clean, sharp scissors or a small serrated knife. Cut the stems cleanly about 1 to 2 cm above the surface of the growing medium, taking care not to drag or crush the delicate stems.
Do not wash the microgreens before storing them — moisture accelerates deterioration. Place the freshly cut greens in a container lined with a sheet of kitchen paper, seal it loosely, and refrigerate. Used within three to five days, they will retain both colour and texture well. Wash just before serving.
Like other microgreens, amaranth does not regrow after cutting. The tray is spent once you have harvested. Many growers start a second tray a week after the first to ensure a continuous supply — a simple staggered sowing schedule takes only a few minutes to establish.
Flavour Profile and How to Use Amaranth Microgreens
Amaranth microgreens have a mild, slightly earthy flavour with a subtle sweetness that sets them apart from more assertive microgreens varieties. They lack the sharpness of arugula microgreens and the pronounced earthiness of radish microgreens. This mildness makes them extremely versatile — they pair as comfortably with delicate flavours as they do with more robust ones, and they never overpower.
The texture is soft and slightly delicate rather than crunchy, which means they wilt quickly under heat. Use them raw and add them to a dish at the very last moment if they are going near anything warm.
Some of the most effective uses:
- As a garnish. A small cluster of magenta stems on soup, grilled fish, or a grain salad adds striking colour with very little effort — the mild flavour complements rather than competes.
- In salads. They mix well with other leaves, bringing colour and gentle earthiness without dominating the bowl.
- On avocado toast. A handful of red garnet amaranth on sourdough with avocado looks restaurant-quality and takes seconds to add.
- In grain bowls. The earthy sweetness pairs well with roasted vegetables, lentils, and quinoa. Add them raw on top just before serving.
- On eggs. Scrambled, poached, or softly fried eggs finished with amaranth microgreens look far more polished than the effort warrants.
The best microgreens to grow guide covers how different varieties compare on flavour intensity, grow time, and difficulty — useful for deciding which crops to add alongside amaranth.
Troubleshooting Common Problems
Mould on the Growing Medium
Surface mould, usually appearing as white or grey fuzzy patches, is the most common issue with amaranth and is almost always caused by excess moisture combined with poor air circulation. Reduce watering frequency, switch to bottom watering, and position a small fan nearby. A light misting with a very dilute hydrogen peroxide solution (3%) can help clear surface mould without harming the seedlings, but good airflow is a more reliable long-term fix.
Pale, Washed-Out Colour
If your red garnet amaranth is growing green or yellow rather than pink and magenta, the tray needs more light. Move it to a brighter position or increase the daily duration under a grow light. Colour improvement is usually visible within 24 to 48 hours of increasing light exposure.
Uneven Germination
Patchy germination — some areas of the tray growing well while others remain bare — is almost always a result of uneven sowing. Using the cross-hatching technique described in the sowing section helps considerably. Uneven moisture distribution during the blackout phase can also cause patchiness; check that the cover is creating a consistent humid environment across the whole tray.
Leggy, Stretched Stems
Stems that grow very tall and thin before reaching harvest height are stretching toward inadequate light. This is more pronounced in amaranth than in many other microgreens because the seedlings grow relatively quickly. Increase light intensity or duration. Leggy stems are not a food-safety issue — the microgreens are still edible — but they tend to be less colourful and have a slightly less satisfying texture.
Damping-Off
Damping-off is a condition caused by soilborne pathogens, most often Pythium or Rhizoctonia species, in which seedling stems collapse and rot at the base. It is favoured by high humidity, cool temperatures, and overwatering. Prevention is easier than cure: use clean trays, fresh growing medium, and ensure good airflow. If you see damping-off in one area of the tray, the rest of the crop can sometimes be saved by immediately reducing watering and improving ventilation, though often the tray is lost.
Comparing Amaranth to Other Microgreens
Amaranth sits in useful middle ground. It grows more slowly than radish (typically ready in six to eight days) but is less demanding than sunflower microgreens, which require pre-soaking and weighted pressing. In terms of flavour, amaranth is considerably milder than either — closer to broccoli microgreens in its gentleness, without any brassica edge.
Where it genuinely stands apart is appearance. No other common microgreen produces the same depth of pink-to-magenta stem colour. If you are new to the category, it is worth understanding how sprouts differ from microgreens before you start — the growing methods are quite different.
Frequently Asked Questions
How Long Do Amaranth Microgreens Take to Grow?
Amaranth microgreens typically take 10 to 14 days from sowing to harvest. Germination usually occurs within 3 to 5 days, and the seedlings reach a harvestable height of 5 to 8 cm in another week or so, depending on temperature and light levels.
Do Amaranth Microgreens Need Soaking Before Sowing?
No. Amaranth seeds are very small and do not benefit from pre-soaking. Soaking makes the tiny seeds clump together, which makes even distribution across the tray much harder. Sow them dry directly onto moist growing medium.
Why Are My Amaranth Microgreens Not Turning Red or Pink?
Insufficient light is the most common reason. The vivid magenta and pink colouring in red garnet amaranth develops in response to light exposure. If your tray has been kept in darkness for blackout germination and then moved to low-light conditions, the stems will remain pale green or yellow. Move the tray to a bright windowsill or under a full-spectrum grow light and the colour should deepen within a day or two.
What Do Amaranth Microgreens Taste Like?
Amaranth microgreens have a mild, slightly earthy flavour with a subtle sweetness. They lack the peppery bite of radish or the brassica sharpness of broccoli microgreens, which makes them versatile and easy to pair with a wide range of dishes. The texture is soft and delicate.
Can I Regrow Amaranth Microgreens After Cutting?
No. Like most microgreens, amaranth does not regrow after harvest. Once you cut the stems above the growing medium, the crop is finished. Sow a new tray if you want a second harvest. Many growers stagger two or three trays a week apart so they always have fresh microgreens ready.
Summary
Amaranth microgreens — especially the red garnet variety — are one of the most rewarding crops a home grower can take on. Their tiny seeds require a little patience and the right sowing technique, but once you crack that, the process is straightforward: dry sowing onto moist growing medium, a blackout period of three to five days at around 20°C to 25°C (68°F to 77°F), then a move to bright light to coax out the vivid magenta colouration that makes them so distinctive. Water from below, keep air moving around the tray, and harvest cleanly at 10 to 14 days. The result is a mild-flavoured, visually striking microgreen that works as well blended into a smoothie as it does finishing a restaurant-style plate.