A compact, long-blooming annual that earns its bed space as both a companion plant and a source of edible petals.
Tagetes patula · also called dwarf marigold, signet marigold
Windows are counted from the average date of your last spring frost.
French marigold roots release compounds that suppress certain soil-dwelling nematodes (microscopic roundworms that damage roots), and the dense flower heads attract beneficial insects. Petals are edible and add color to salads.
A little history. Native to Mexico and Guatemala, Tagetes patula was introduced to Europe in the 16th century. Despite the common name 'French marigold,' the plant has no botanical connection to France.
Sow seeds ¼ inch (6 mm) deep, and aim for 9 inches (25 cm) between plants once thinned. Press seeds shallowly into moist soil and keep the surface from drying out; seeds need light to germinate — do not bury deeper than ¼ inch. Seedlings emerge in 5–10 days.
Either works well; needs at least 6 inches of soil depth and good drainage. In containers: 1-gallon pot per plant minimum; 3-gallon preferred for bushy varieties.
Water deeply once or twice a week; allow the soil surface to dry slightly between waterings. Water when the top inch of soil feels dry to the touch. Aim for about 1 inch per week including rain.
Apply a balanced fertilizer at planting; side-dress (scatter fertilizer along the row and water in) once mid-season if growth looks pale. What to use: balanced 5–5-5 organic or compost at planting; avoid excess nitrogen, which promotes leaves over flowers.
Pinch out the central growing tip when seedlings have 3–4 sets of true leaves (the full-shaped leaves that follow the first rounded seed leaves) to encourage branching. Deadhead (remove spent blooms) every few days to sustain flowering.
It's ready when harvest petals when the flower head is fully open and petals are firm and brightly colored. For companion-planting benefit, leave some flowers to mature fully on the plant. Snap or cut individual flower heads at the base of the stem in the morning after dew has dried. Pull petals free from the bitter green base (receptacle) before eating.
Use petals fresh the same day for best flavor and color. Whole heads can be kept in a single layer in a sealed container in the refrigerator for up to 2 days.
Sow a second batch indoors 4 weeks after the first to maintain a continuous supply of fresh transplants and extend the bloom season into fall.
Tomato
Grown as a dense block and dug into the bed at season's end, French marigold roots measurably reduce root-knot nematode numbers, which spares tomato roots the following year. A few plants dotted along the edge do not do this, and marigolds do not deter Colorado potato beetles.
Bell Pepper
The open flower heads feed hoverflies, lacewings, and tiny parasitic wasps whose young hunt the aphids that cluster on pepper shoot tips. Keep some blooms un-deadheaded so the nectar supply is steady.
Basil
Both plants like the same warm, well-drained ground, and if you let a few basil spikes and marigold heads flower they can together keep a steady nectar supply for hoverflies and small parasitic wasps through midsummer.
Cucumber
Cucumbers need insects to move pollen between male and female flowers, and a marigold edging in bloom often draws more bees into the bed. Plant it where it will not be shaded out by the vines.
Carrot
The strongly scented foliage can help hide the smell of carrot tops from carrot rust fly, which finds its host by odor. Expect partial help under low pest pressure, not a substitute for a fine mesh row cover.
Fennel
Fennel roots release compounds that stunt most garden plants growing close by, marigold included. Give it its own corner well away from the bed, where its flat flower heads still earn their keep feeding hoverflies and tiny parasitic wasps.
Green Bean
Old companion charts keep marigolds and beans apart, though no mechanism has been demonstrated and trials have not supported the pairing. If you have space, separate them; if you do not, there is little reason to expect harm.
Easy-going — French marigold can grow almost anywhere in the rotation without a strict rest.
The pea and bean family, the cabbage family or the tomato family thrive in this ground next season.
A light feeder that leaves the soil loose and, when the chopped roots are dug in, less friendly to root-knot nematodes. Give the daisy family a one-year gap before this spot grows them again. Legumes, cabbage-family crops, and tomato-family crops all follow well here.
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