Marigolds

Marigolds are a favorite in our Sunnyvale garden. They attract butterflies, bees, ladybugs, and other beneficial insects. Give them full sun and some well-draining soil and watch them bloom from spring until fall.

Marigold seeds germinate quickly, within just a few days, and bloom in about 8 weeks. Marigolds are a great companion in your vegetable garden and can help protect your veggies from predators and pests.

Zones:

Annual. Marigolds are appropriate for seasonal use in all zones.

Height/Spread:

There are varieties available from 6 inches to 4 feet tall, and 6 inches to 2 feet wide. See ‘Types’ for more specific information on sizes.

Exposure:

Full sun

Bloom Time:

spring until first frost

Color:

Marigolds are available in shades of orange and yellow; some with highlights of red, gold, copper or brass.

Types:

There are approximately 50 species of marigold, but the 3 most common are:

Tagetes patula (French marigold): The most common type found in local nurseries, these range in size from 6 to 12 inches tall and 6 to 9 inches wide. They are compact annuals with double flowerheads up to 2 inches across.

Tagetes erecta (African marigold): These are the tallest variety of marigolds and range in height from 1 to 4 feet, and have a 1 to 2 foot spread. Their large flowerheads can reach up to 5 inches across, are densely double and pompon-like.

Tagetes tenuifolia (Signet marigold): Upright annuals that grow up to 12 inches tall and wide. Flowerheads are single and are usually 1 inch in size. The flowers are edible and often used as a bright topper for salads, pasta and vegetables.

Calendula, also called pot marigold, is not related to the common yellow and orange marigolds that most people know, but is an herb often grown for medicinal purposes. Mexican tarragon (Tagetes lucida) is related, but is mainly grown for culinary as well as medicinal uses. Mexican marigold (T. lemmonii) is also related, but is an evergreen shrub.

When to plant:

Taller African varieties (Tagetes erecta) should be planted in early spring after all danger of frost has passed. Starting these taller varieties early in the season will allow them more time to grow and mature. French and Signet types (T. patula and T. tenuifolia) can be planted any time from spring through mid-summer.

Where to plant:

Most marigolds prefer to be located in an area with full sun but will tolerate some shade. During times of extreme heat, some afternoon shade is beneficial. T. erecta varieties should be planted in an area protected from strong winds and damaging rainfall. These taller varieties may also require some light staking for support.

How to plant:

Marigolds germinate quickly, sprouting within a few days and blooming in about 8 weeks, making them easy to grow from seed. Sow seeds directly outside after all danger of frost has passed and the soil has begun to warm up. Sow seeds 1 inch apart and water thoroughly after planting. After the seeds sprout, they should be thinned to the following guidelines: French or Signet varieties 8 to 10 inches apart, and African varieties 10 to 12 inches apart. Use landscape scissors or small garden shears to cut the seedlings out, as pulling them out can disturb the roots of the seedlings left behind. Seeds can be started earlier indoors, but with their fast germination time, this really isn’t necessary. Seedlings can be transplanted when 2 inches tall.

When transplanting marigolds purchased at a nursery, dig and loosen the soil about 6 inches down, with the final planting hole just slightly larger than the rootball. Backfill with soil and press firmly into place. Water thoroughly. Adding a 1 to 2-inch layer of mulch between the plants will help keep the soil moist and discourage weeds.

Other:

Marigolds grown in containers can become overcrowded, so be sure to space them accordingly.

Pruning:

Deadheading will improve the appearance of the plant and encourage further blooming later in the season. Pinching young plants will help promote bushier growth. Pinch and remove new growth at the top of the plant as close as possible to the next leaf nodes on the stem.

Soil:

Marigolds aren’t too picky about their soil, but will be their best in moderately fertile, well-drained soil. If planted in clay soil or an area that doesn’t drain well, they may not perform as expected.

Amendments & Fertilizer:

When transplanting, a 5-10-5 fertilizer can be added, but is completely optional. Marigolds grown in-ground generally don’t require any fertilizer. In fact, if fertilizer is applied during the growing phase, it can boost foliage growth at the expense of flower production. Marigolds in containers can benefit from a diluted liquid fertilizer watered in occasionally.

Watering:

It is best to water marigolds at the base of the plant and not from overhead. The densely double flowerheads will tend to rot with excess moisture. Allow the soil to dry somewhat between waterings, but do water regularly in high heat or dry weather. Marigolds growing in containers should be watered daily as containers dry out quickly.

Propagation:

To save seeds, allow the flowerheads to fade and dry intact on the plant. When fully dried, remove the petals and shake out the seeds. Not all flowerheads will produce seeds, but most should. Remember that hybrids will not come true from saved seed.

Diseases and Pests:

Marigolds can be susceptible to gray mold, bacterial leaf spot, powdery mildew and root rot. Pests such as leaf miners or spider mites may also be a problem. Interestingly enough, marigolds also do their fair share of repelling several types of insects. According to the New York Botanical Garden, marigolds can help keep away mosquitoes, aphids, thrips, whiteflies, Mexican bean beetles, squash bugs, tomato hornworms and nematodes.

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