Grenade Orange and Zanzibar Orange safflower flowering in a sunny South African cut-flower bed

How to Grow Carthamus (Safflower) in South Africa

Grow bold orange safflower stems for fresh bouquets, dried arrangements and sculptural green buds. This guide explains how to sow, establish and care for the two Carthamus tinctorius cut-flower selections available from GARDENING.co.za: Grenade Orange and Zanzibar Orange.

Quick Grow Facts

Plant type: Upright annual cut flower
Botanical name: Carthamus tinctorius (safflower)
Named selections: Grenade Orange and Zanzibar Orange
Seed form: Grenade Orange is treated; Zanzibar Orange is raw
Best South African sowing window: Spring to early summer after damaging frost, with regional adjustments below
Position: Full sun; light afternoon protection can help stem quality in exceptionally hot districts
Medium and depth: Fine, free-draining seedling mix or a loose prepared row; sow 1 mm deep and cover lightly
Light: Germination light is not required because the seed is lightly covered; move emerged seedlings into strong light immediately
Germination: About 10–14 days at approximately 20–22°C in evenly moist, aerated media
Pretreatment: None; do not soak, scarify or chill seed, and never rinse treated Grenade Orange seed
Preferred method: Direct sow; if trays are necessary, use deep cells and transplant young plugs before roots circle
Spacing: 15 cm in an intensive supported cut row; 20–25 cm for more branching and airflow in a garden bed
Growth form: Upright, tap-rooted and branching; optional support in sheltered gardens and recommended support in exposed cut rows
Height: Grenade Orange about 81–102 cm; Zanzibar Orange commonly about 70–80 cm under professional cut-flower guidance, with site and planting density affecting final stem length
Crop time: Allow roughly 10–16 weeks from direct sowing to the first useful cuts in suitable weather
Use: Fresh orange flowers, green-stage texture and air-dried stems
Safety: Grow the stocked products as ornamentals. Do not eat seed or flowers; treated Grenade Orange seed must be kept away from food, children, pets and wildlife.

Grenade Orange

Grenade Orange is the shorter, uniform professional cut-flower selection. It produces round green buds and orange flower heads on upright stems, with rounded leaves bred to be thornless. The stocked packets contain treated seed, so keep the seed dry, use it only for sowing and wash your hands after handling it.

Seed: Treated; sow directly from the packet without soaking or rinsing.
Growth form: Upright stems of relatively uniform length with rounded buds and smooth rounded leaves.
Height and spread: About 81–102 cm high and 20–25 cm wide.
Spacing: The packet states 15–23 cm; use the closer end for supported cut rows and the wider end for airflow and branching.
Outcome: Fresh or dried orange stems, or firm green buds cut before colour develops.

Zanzibar Orange

Zanzibar Orange is a separate raw-seed selection with fiery orange-and-gold, thistle-like flower tufts, dark green foliage and more visibly branching flower clusters. Commercial sources describe it as smooth to nearly spineless, but occasional firm or prickly bracts can still occur, so wear gloves if your skin is sensitive.

Seed: Raw; no soaking, scarification or chilling is needed.
Growth form: Upright and branching, with several geometric buds and flower heads carried on sturdy stems.
Height: Common professional guidance is approximately 70–80 cm; growing conditions and density can change final stem length.
Spacing: The packet states 15–25 cm; allow 20–25 cm in humid gardens.
Outcome: Fresh orange stems, green-stage texture and flowers that hold their colour well when air-dried.

When To Sow Safflower In South Africa

Winter-rainfall Western Cape

Direct sow from late winter into spring when saturated soil has drained, the seedbed is warming and prolonged cold rain is easing. Raised rows help in clay or low-lying ground. Keep the row evenly moist through emergence, then water deeply as the Cape moves into its dry, windy summer. Install support before stems stretch in exposed wind corridors.

Frost-prone interior

In Gauteng, the Free State, North West, the colder KZN Midlands and inland Mpumalanga, sow after the local danger of damaging frost has passed. Young safflower rosettes can tolerate some cold, but elongating and flowering stems are vulnerable, so do not use general frost tolerance as a reason to plant the cut crop too early. Deep-cell plugs may be started four to five weeks before the expected planting date and hardened carefully.

Humid coast and KZN Midlands

Choose a bright spring or drier shoulder-season window rather than forcing the crop through the wettest, most humid period. Use full sun, free drainage and the wider 20–25 cm spacing. Water at soil level early in the day, keep weeds down and watch for brown leaf or bract spots, grey mould and flower-head rot after prolonged wet weather.

Hot-dry or subtropical interior

In the Northern Cape, Limpopo and Lowveld, establish plants from late winter into early spring once frost risk has passed locally and before extreme heat arrives. Safflower becomes drought tolerant as its taproot develops, but seed and young plants still need steady moisture. Water deeply, let the upper soil begin to dry between established-plant irrigations and consider light afternoon protection where reflected heat is severe.

How To Sow Carthamus Seed

Direct sowing: the preferred method

Choose a full-sun bed with at least 25 cm of loose, free-draining soil. Remove perennial weeds before sowing because young safflower is a poor competitor.
Rake the surface fine and level. Water a dry seedbed before sowing and allow excess water to drain.
Place seed where each plant will grow and cover with approximately 1 mm of fine soil or vermiculite. The seed should be covered, not left exposed.
Keep the seed zone evenly moist and aerated. Do not flood the row or allow a hard crust to form.
Aim for approximately 20–22°C and allow 10–14 days for emergence.
Thin carefully to 15 cm for an intensive supported cut row or 20–25 cm for a garden display. Cut unwanted seedlings at soil level rather than disturbing neighbouring taproots.

Tray sowing when weather or pests make it useful

Sow one seed per deep cell, 1 mm deep, in clean free-draining seedling mix. Keep the tray at about 20–22°C until emergence and move seedlings into strong overhead light immediately. Maintain airflow and even moisture without leaving the tray standing in water.

Transplant at about four to five weeks, while the plug is young and the root ball holds together but before roots circle the cell. Harden plants over five to seven days, handle the plug rather than the stem, and set it at the same depth. A checked or root-bound taproot can produce a permanently stunted plant, which is why direct sowing remains the safer default.

Spacing, Support And Pinching

Use 15 cm spacing where straight cut stems and efficient row use matter, then add horizontal flower netting before the plants elongate. Use 20–25 cm spacing for a more branched garden plant and better airflow. In windy sites or fertile soil, one or two levels of netting keep the top-heavy flowering stems upright.

Do not pinch routinely in a home cutting row. Letting the terminal bud develop gives the simplest crop and keeps timing predictable. A professional high-pinch programme may remove the apical flower bud around week eight or nine to stimulate laterals, but that changes the plant form and harvest schedule; trial it on a few plants only if a more branched spray is your goal.

Soil, Water And Feeding

Safflower needs full sun and drainage more than rich soil. A loose loam or sandy loam is ideal, but raised rows can make heavier soil workable. Incorporate a modest amount of mature compost before sowing if structure is poor. Avoid fresh manure and heavy nitrogen feeding, which can produce lush growth, weak stems and lodging.

Keep the seed zone and young root ball consistently moist through establishment. Once the taproot is working into the bed, change to deeper, less frequent watering and allow the surface to begin drying between irrigations. Drought tolerance does not mean the crop should be stressed during germination, early stem extension or bud development; severe stress at those stages shortens stems and reduces flower quality.

Pests, Disease And Safe Care

Inspect the growing tips and buds for aphids and thrips. Start with a firm water spray, removal of badly affected tips and support for beneficial insects. If a spray is needed, use only a product registered in South Africa for the pest and ornamental crop, and follow its label exactly.

Prolonged humidity and leaf wetness favour Alternaria leaf spot, Botrytis and other leaf, root or head rots. Space plants well, rotate away from safflower and related disease hosts, water at soil level in the morning and remove badly diseased material. Never improvise seed treatments: Grenade Orange is already treated, while Zanzibar Orange is supplied raw.

Harvesting Fresh, Green And Dried Stems

Fresh orange flowers: Cut in the cool part of the day when the first florets are opening and clear orange colour is visible. Buds cut before colour shows may not open after harvest.
Green texture: Cut firm geometric buds before the petals unfold. Grenade Orange is particularly useful at this stage.
Orange dried flowers: Harvest once the flower heads are open and dry to the touch. Remove lower foliage, tie small bunches and hang them upside down in a shaded, dry place with good airflow.
Green dried material: Trial a separate cut at the firm green-bud stage, then dry it in the same shaded, ventilated conditions.

Use clean tools, strip any foliage that would sit below the water line and place fresh stems into a clean bucket promptly. Safflower is mainly a one-cut crop, so sow two or three small successions a few weeks apart if you want a longer home harvest.

Troubleshooting Germination And Establishment

No emergence after 14 days: The seed may have dried, been buried too deeply, sat in cold or saturated media, or struggled under a crusted surface. Check moisture and temperature before disturbing the row.
Patchy germination: Uneven depth or watering is usually responsible. Keep the 1 mm cover consistent and water with a fine rose.
Seedlings collapse: Waterlogged mix, poor airflow or contaminated trays can cause damping-off. Improve drainage and sanitation; do not resow into the same wet medium.
Plants stall after transplanting: The plug was probably held too long, the taproot was bent or broken, or the seedling was not hardened. Direct sow the next batch or transplant younger deep-cell plugs.
Short stems and early small buds: Heat, drought, root restriction, crowding or a late planting can check extension growth. Protect establishment, water deeply and adjust the next sowing date.
Soft leaning growth: Too much nitrogen, rich wet soil or late support can cause lodging. Reduce feeding and install netting earlier.
Brown spots or rotting heads: Humidity, overcrowding and leaves remaining wet overnight favour disease. Increase airflow, water earlier at soil level and remove affected material.

Safety And Use Limitations

These stocked packets are sold for ornamental flower production. Grenade Orange seed is treated: do not eat it, feed it to animals, rinse off the treatment or use it near food preparation, and keep it away from children, pets and wildlife. Zanzibar Orange seed is raw, but the current packet does not certify the crop for culinary use. Commercial sources disagree about edible use, so this guide does not recommend eating either stocked product’s seed, petals or other plant parts.

Grenade Orange has breeder-confirmed thornless leaves, and Zanzibar Orange is commonly described as nearly spineless. Neither description guarantees that every bract is soft. Wear gloves if you are sensitive to prickly flower heads and take care when cutting mature stems.