Artichoke plants (Cynara scolymus) are herbaceous perennials that are members of the Asteraceae family, a group that includes thistles, dandelions, and sunflowers. They are short-lived perennials in warmer climates but are normally grown as annuals in cooler regions.
Artichokes are usually grown for their edible flower buds, which are harvested before the flowers open. Artichokes leaves are silvery-green in color with a long, arching shape. Although they look soft, the leaves can be quite prickly. The plant stems are thick and fleshy.
The flower buds are the parts of the plant sold in produce aisles. At the base of the bud is the tender, flavorful artichoke "heart." If allowed to blossom on the plant, artichoke flowers open into large, dome- or muff-shaped purple thistles that are surprisingly fragrant.
Artichokes are planted at different times of the year, depending on the climate. Where they are grown as annuals, they must be planted in spring. In warmer zones where they survive as perennials, they are often planted as seeds in late summer or as young plants (or transplants) in mid-autumn. They typically need 85 to 100 days to reach harvest.
|Common Name||Artichoke, globe artichoke, French artichoke, green artichoke|
|Botanical Name||Cynara scolymus|
|Plant Type||Herbaceous, perennial, biennial|
|Mature Size||3-6 ft. tall, 4-5 ft. wide|
|Bloom Time||Summer, fall|
|Hardiness Zones||7-11 (USDA)|
Because artichokes often take two years to flower, they are typically sold as container plants in their second year or as established root crowns. They become large plants and should be spaced at least four feet apart, but six feet is even better. Plants grown as annuals, or where the tops will be killed back by frost, will not grow as large and can be spaced a little closer. Harvest the buds for eating before they develop into thistle-like flowers.
When grown within their hardiness range, artichoke plants should produce for about three to five years and will develop side shoots at their bases. At this time, you can lift, divide, and replant the new shoots.
Artichokes grow best in full sun. They can tolerate some shade, but the flower buds will suffer.
Artichokes prefer sandy, well-drained but fertile soil. A soil pH slightly on the alkaline side is best. Slightly sandy soil (think: Mediterranean) is ideal. Good drainage is crucial to prevent the roots from rotting, especially in areas where they will be overwintered. However, the soil must also be able to retain water long enough to allow the roots to take it in during hot summers.
When growing artichokes as perennials, it is especially important to amend the soil before planting to ensure they will grow well in future years. If your garden soil is poor, consider growing your artichokes in raised beds.
Artichokes require lots of moisture for best growth. Deeply water artichoke plants at planting time, and water them deeply at least once or twice per week. Soil must be moist for buds to develop. Water keeps flower buds fleshy and tender and helps develop a strong root system that will keep the plants upright.
Temperature and Humidity
This plant prefers warm weather, such as that found in the Mediterranean region and in California. Excessive heat will cause the plant to bloom prematurely. When grown as perennials, artichokes favor areas with mild winters (50 to 60 degrees Fahrenheit) and cool, moist summers (70 to 80 degrees Fahrenheit). Very hot soil will make the plants flower too quickly, so apply a thick mulch around the base of the plants to keep the soil cool.
Artichokes are heavy feeders, so add compost or aged manure into the planting hole at planting time. Alternatively, at planting time you can apply an organic balanced fertilizer. For the amount of fertilizer to use, follow the product label instructions. Feed the plants periodically throughout the growing season.
Types of Artichokes
Here are several excellent varieties of artichoke:
- 'Big Heart' is a thornless variety that can handle some heat.
- 'Green Globe' is the variety most often grown commercially in California, but it does not adapt as well to less-than-ideal growing conditions. Produces good quality buds. Also known as 'Vert Globe'.
- 'Imperial Star' is widely adaptable, easy to grow from seed, and bred to be grown as an annual. Bears four-inch wide, spineless buds. This is the variety recommended for gardeners in zones 6 and colder.
- 'Purple of Romagna' is a tender Italian heirloom favored by chefs.
- 'Violetto' is an Italian heirloom prized for its production of dozens of small side shoots.
When harvesting artichokes, simply cut them from the plant at a 45-degree angle when they are about three inches in diameter. Cut spent stalks down to the ground to allow room for other stalks to grow. When the plant is done bearing fruit, cut it down to just above the ground and apply a heavy layer of mulch.
Though it is easier to grow artichokes from seed, it is possible to grow new artichoke plants from the offshoots that most artichokes produce starting in their second or third year. This can only be done in warm climates where artichokes overwinter.
- During the fall or winter. remove some soil to expose the roots of the plant.
- Remove the shoots and the roots of the shoots with a sharp knife. The shoots should be at least eight inches long.
- Backfill the soil around the original plant.
- Plant the offshoots immediately in well-draining soil at least six feet away from the parent plant.
- Deeply water the new plant and keep it moist. If it doesn't rain, apply at least one inch of water per week. New growth should appear within a few weeks.
How to Grow Artichokes From Seed
Start seeds indoors, at least eight weeks before your average last frost date. Plant seeds 1/4 inch deep in trays or pots filled with a moistened seed starting mix. Soil temperature needs to be warm for germination, so place the seeded tray or pot on a heating mat or a warm space such as the top of the refrigerator or a table above a heat vent. Seeds should germinate within 7 to 21 days. Harden off the seedlings before planting them outside, but don't wait until all danger of frost has passed—artichokes need to experience a slight chilling (not freezing) before they will set buds. This can be accomplished by putting your plants out in mid-spring and exposing them for a week to ten days to temperatures of about 50 degrees Fahrenheit or a little lower.
If you try saving seeds from your artichokes, they might not grow true, producing plants that vary greatly from the parent plant. You will have better success with purchased seed that has been grown under controlled conditions.
If you want to grow artichokes as perennials, adapt your overwintering methods to your USDA Cold Hardiness Zone and climate:
- Zones 8 and higher: After the last harvest in fall, cut the plants to soil level and cover with two to four inches of organic mulch, like straw.
- Zones 6 to 7: After the last harvest in the fall, cut the plants down to about 12 to 18 inches. Cover the plant with organic mulch, like straw, leaves, or even compost, and then cover that with a large basket. Mound another layer of straw or leaves over the basket and cover everything with a waterproof tarp.
- Zone 5 and cooler: You can follow the method described for zones 6 to 7 but overwintering artichokes in those climate zones is only likely to succeed in a mild winter.
Whatever your zone or method, remove all coverings in spring as soon as the soil has thawed and no hard frosts are expected.
Common Pests and Plant Diseases
Few pests attack artichokes. Slugs can be a problem during damp weather, especially with younger, tender leaves. Aphids can also become a nuisance, but they can be hosed off before they take over. Giving the plants enough space for air to flow freely will help minimize aphid problems.
Botrytis, or gray mold, can affect leaves and flower bracts. It is most pervasive on damaged leaves, which will turn brown and then grayish. Remove affected leaves as soon as the disease is apparent. For severe infections, use a fungicide labeled for edible plants, such as neem.
Can I grow artichokes through the summer?
Although still extremely popular in their native Mediterranean region, artichokes are not commonly grown in the U.S.—California is the only state with a large commercial artichoke industry. There, the peak growing season is from March to May, but if you plant some at home, you can have artichokes maturing throughout the summer.
Do I have to harvest the artichokes?
You can grow them as a lovely garden plant instead of an edible. Because few animals bother with artichokes, don't be afraid to plant them in your ornamental borders as edible landscaping. You can still harvest them at will, but the stately plants and textural leaves will add visual interest throughout the season.
How do I harvest artichokes?
In most areas, buds begin forming in early summer. The center bud will mature first and can be harvested as soon as it has reached about three inches in diameter. Harvest while the bracts are still tightly folded and the bud feels firm. You can cut a one- to three-inch portion of the stem along with the bud, to make it easier to work with.
After the center bud is cut, side shoots will begin producing smaller buds. Harvest when they are firm and reach about one to three inches in diameter. Small buds can be extremely tender and flavorful, requiring only a slight heating-through before eating.
University of California, et al. “Artichoke.” Ucanr.edu, https://mgsantaclara.ucanr.edu/garden-help/vegetables/artichoke/
Woods, W. M. “Artichokes.” Science (New York, N.Y.), vol. 173, no. 4003, 1971, p. 1195, https://doi.org10.1126/science.173.4003.1195