An easily grown half-hardy annual, marigolds are very popular to grow in gardens all over the world. They are not fussy about where they grow provided they have plenty of sunshine.
In the past the tall, larger-flowered Tagetes erecta was often called African marigold and the shorter, smaller Tagetes patula was known as French marigold, but the increasing complexity of hybrid varieties mean that there are fewer distinctions between the strains of seed offered for sale.
Another marigold species, Tagetes minuta is distinct, being a very large plant with tiny flowers. It is usually grown by organic gardeners for its beneficial properties on soil, as the roots exude chemicals which repel couch grass and eelworms.
Seed needs to be sown indoors but plants can be grown outside during the summer, where they will flower until the frosts. Minimum temperature 10°C
From seed. They are easy to sow in a tray or pot. Seeds should be set about 2cm apart. Germination is rapid at 19°C.
Keep seedlings warm, and move onto larger pots when they have four to six true leaves. Harden off and plant out in a sunny position when the weather is warm enough, at about 8cm apart. Tagetes minuta will need a stake to support it. Water well until established.
Remove spent flowers as they die off, water in dry weather and feed with a high potash fertilizer occasionally to prolong the flowering period.
In India African marigolds are often grown as standards. To do this, rub the side shoots off a marigold plant and tie the bare stem to a stick so it keeps growing upwards.
When it is about 45cm tall, allow the top to bush out, and develop normally but keep rubbing off any side shoots from the stem.
Slugs and snails like young plants, otherwise trouble-free.
Marigold leaves contain chemicals that can cause dermatitis and a phototoxic reaction - where the sap from the plant reacts with sunlight to irritate the skin. As a precaution, wear gloves and long sleeves when handling these plants.