How to Grow Globe Amaranth Seeds

Grow Guide #2273
Family: Amaranthaceae
Binomial name: Gomphrena globosa
Life Cycle: Annual

This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Globe Amaranth (Gomphrena globosa).

When to Sow Globe Amaranth Seeds

Globe Amaranth is a warm season crop. Use the table below to identify the best time of year to sow globe amaranth seeds in your climate.

  JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Cool
Temperate
Sub-Tropical
Tropical
Arid

Preparation

Globe Amaranth plants are best grown in full sun. Choose a location that will receive at least 6 hours of full sun each day.

Globe Amaranth plants need a well drained soil enriched with plenty of organic matter. Prepare soil by weeding it thoroughly, digging it over to loosen it and adding aged animal manure or compost. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.

Globe Amaranth plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 20 litres is recommended for globe amaranth. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.

How to Sow Globe Amaranth Seeds

Globe Amaranth seeds do not require any treatment (eg soaking, stratification) before sowing.

Globe Amaranth seeds can be sown directly into the garden OR seedlings can be raised in trays or other containers and transplanted to the garden once established.

Sow Direct

  1. Sow seeds directly in the garden 5mm deep and 50cm apart.
  2. Keep soil moist but never wet or dry.
  3. Seeds should germinate in around 14-21 days at a soil temperature of 20-25°C.
  4. Young seedlings will need protection from pests, pets and weather until they are established.

Raise Seedlings

  1. Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
  2. Sow seeds 5mm deep.
  3. Keep soil moist but never wet or dry.
  4. Seeds should germinate in around 14-21 days at a soil temperature of 20-25°C.
  5. Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
  6. Plant out, spacing plants 50cm apart.

Globe Amaranth is a tender crop that’s sensitive to frost. Do not transplant seedlings or sow seeds outside until all danger of frost has passed.

How to Grow Globe Amaranth

Globe Amaranth plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.

If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a high-potassium fertiliser or one formulated for flowering plants can be beneficial:

  • Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
  • Apply liquid fertiliser at the recommended rate and frequency while plants are fruiting or flowering.

Optional: Pinch out the growing tips of globe amaranth plants to encourage denser growth with stronger stems and more flowers. Using sharp secateurs or snips remove the top set of leaves, cutting just above a set of lower leaves.

Globe Amaranth plants should flower in approximately 80-90 days.

If growing globe amaranth for cut flowers, use sharp snips or secateurs to cut the longest stems possible, removing the lower leaves and placing the stems immediately in a clean bucket of water. Learn more about cutting and conditioning homegrown flowers here.

Deadhead globe amaranth flowers regularly during the growing season. Using sharp secateurs or snips cut fading or dead flowers off just above a set of leaves. Removing old flowers regularly will encourage plants to produce more flowers. Learn more about deadheading flowering plants here.

Globe amaranth flowers can be dried. Cut several stems with flowers, remove the leaves from the stems and tie them together in a bundle. Hang the bundle upside down in a cool, dry space until the flowers are dry.

Common Problems when Growing Globe Amaranth

Like all plants, globe amaranth is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing globe amaranth plants:

  • Aphids
    Aphids are small (2-4mm long) sap-sucking insects that congregate on the new shoots or the undersides of leaves. They can cause leaves to wilt or become discoloured, and also excrete honeydew which can attract ants and other insect pests. To manage aphids, remove them by spraying with a garden hose, apply a soap or alcohol spray, or encourage predatory insects to your garden. Read more about aphids here.
  • Frost damage
    Frost damage can cause leaves to wilt and go black. Do not plant seedlings in the garden until all danger of frost has passed in spring, and harvest plants before winter. Prune all frost-damaged leaves to avoid them rotting on the plant.
  • Downy Mildew
    Downy mildew is a fungal disease that causes yellow to grey-brown patches on leaves, especially the undersides. Water plants at soil level (not on the leaves), remove and destroy affected leaves and do not overcrowd plants to ensure adequate air flow. If problems persist, spray with a homemade milk spray or fungicide.

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