How to Grow Marigolds From Seed: A Step-by-Step Guide

Marigolds are among the easiest flowers to grow from seed, and starting your own is far cheaper than buying plants. A packet of seed costing a pound or two yields dozens of plants, all ready to go in the garden exactly when conditions are right. Whether you want vibrant French marigolds for edging or tall African marigolds for a dramatic border, the process is the same.

Choosing Your Seeds

French marigolds (Tagetes patula) are compact (20–40 cm), fast-maturing, and ideal for edging, containers, and vegetable companion planting. African marigolds (Tagetes erecta) grow taller (40–90 cm), take longer to flower, and make bold statement plants. Signet marigolds (Tagetes tenuifolia) are smaller with a spreading habit and edible flowers. Read the packet to check expected flowering time — African marigolds need to be started earlier than French types.

When to Sow

Indoors with heat: sow French marigolds 6–8 weeks before your last frost date; African marigolds 8–10 weeks before. Outdoors without protection: sow direct once soil temperature is consistently above 18°C and all frost risk has passed. Marigold seeds germinate in 5–7 days at 21–24°C. Cold soil dramatically slows germination and can cause seeds to rot.

Sowing Method

Fill small pots or seed trays with fine seed compost. Press seeds lightly into the surface — they are large enough to handle individually, so space them 2–3 cm apart if sowing in a tray. Cover with a thin layer of vermiculite or fine compost (about 5 mm). Water gently using a fine rose or by sitting the tray in water until the surface darkens. Cover with a propagator lid or cling film to retain moisture and place somewhere warm (an airing cupboard works well until germination). Remove the cover as soon as seedlings emerge and move them to a bright, warm windowsill.

Caring for Seedlings

Marigold seedlings need bright light to avoid becoming leggy. A south-facing windowsill is ideal; supplement with a grow light if natural light is insufficient. Water when the surface of the compost starts to dry — do not overwater at this stage. Once seedlings have two pairs of true leaves, pot on individually into 7–9 cm pots. Pinch out the growing tip when plants have three to four pairs of leaves to encourage branching.

Hardening Off and Planting Out

About two weeks before planting out, begin hardening off seedlings by placing them outside in a sheltered spot during the day and bringing them in at night. Gradually increase outdoor exposure over 10–14 days. Plant out after your last frost date into prepared soil or containers. Space French marigolds 20–25 cm apart, African types 30–40 cm. Water in well and they will establish quickly.