Marigold 
Calendula officinalis
Family Asteraceae
Marigold is an aromatic seasonal flower that grows around 60cm tall. The flowers are vibrant yellow and orange. Marigolds are now grown in most temperate areas around the world and is said to be native to southern Europe (1). There are numerous cultivars with different colour and size flowers. There is some record of the flowers being used since ancient times as a medicinal herb and a dye. 
Growing Guide
Ideal Environment 
Marigolds are ideal for a sunny (or partially shady) spot and are quite tolerant of average to slightly poor soils but you will get healthier plants and better flowers with rich, well draining soil. You can add compost and organic fertiliser.
How to Plant 
Marigolds grow easily from seeds and can be planted during the spring and summer. Plant the seeds 1cm deep and about 20cm apart or thin them out.
How to Water 
Water immediately after sowing the seeds, keep the small plants reasonably moist but not wet. After that you can water Marigolds one or twice a week during dry periods or if it has rained less than 30mm.
Companion Planting 
Marigolds are really great to have in the garden (especially a vegetable garden) because the odour repels many unwanted insects and attract bees. It is said to enhance the growth of basil, cucumbers, eggplants, potatoes, squash and tomatoes. At least one or two sources say one should avoid planting them close to beans, cabbage and broccoli.
How to Propagate 
Marigolds are best planted from seeds. You can start indoors in trays if you live in a colder area, but Marigolds grow pretty quickly and can be sown directly outside as long as there is no risk of frost. Let some flowers dry on the plant, remove the dried petals and break open to remove the seeds and save them for next season.
How to Harvest 
Harvest the flowers during the summer on a warm dry day and dry the whole flower heads in the shade on a rack or use immediately.
Information & Research
Key Constituents 
Flavonoids, triterpenoid saponins, carotenoids, resin, volatile oil (1, 3).
Key Actions 
Anti-inflammatory, relieves muscle spasms, astringent, heals wounds, antiseptic, detoxifying, antiviral, antiprotozoal, anti-fungal, anti-bacterial, lymphatic, phytoestrogenic (1, 3).
Research 
There have been quite a few studies on Marigolds that suggest that Marigold extracts may have anti-viral, anti-genotoxic and anti-inflammatory properties in vitro (13).
Preparations & Uses
Parts Used 
The flowers are used primarily, but I have seen some books that include stems in ointment recipes, but from research it appears that the most important constituents are in the flower heads. The flowers petals are also edible.
Preparations 
Make an infusion for infections, infused oil (with coconut oil worked great) for inflamed skin and eczema, a tincture for internal use, an ointment or cream for cuts, burns and varicose veins.
Uses 
Marigold preparations are used for athele’s foot, bites and stings, breast tenderness, digestive infections, inflamed skin or rashes, excema, varicose veins and wounds or bruises (1). Use the flower petals in salads or garnish in vegetable, fish and egg dishes. You can also make an insect repellent spray from Marigold by using an infusion.
Other Flowers
