Artichoke plants are herbaceious perennial plants, members of the Asteraceae family of plants, 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 the edible flower buds, which are harvested before the flowers open. The unopened bud has overlapping rows of spine-tipped green bracts enclosing the actual flower parts. At the base of the bud is the tender, flavorful artichoke "heart," which is the part that is cooked and eaten.
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 planted in the home garden, you can have artichokes maturing in your home garden throughout the summer. Make sure you have space, though; these are very large plants.
The leaves of artichokes are silver-green in color with a long, arching shape. Although the looks soft, these leaves can be quite prickly. The stems of the plant are thick and fleshy. The flower buds are what are sold in produce aisles. The bracts are tightly folded over the enclosed flower parts. If allowed to blossom on the plant, artichoke flowers open into large, dome- or muff-shaped purple thistles that are surprisingly fragrant.
- Botanical Name: Cynara scolymus
- Common Names: Artichoke, globe artichoke, French artichoke, green artichoke
- Plant Type: short-lived herbaceous perennial
- Mature Size: 3 to 6 feet in height, 4 to 5 feet in width
- Sun Exposure: Full sun
- Soil Type: light, Fertile, well-drained soil
- Soil pH: 6.5 to 7.5
- Bloom Time: Late summer, early fall
- Flower Color: Purple
- Hardiness Zones: 7 to 11; normally grown as an annual in zones 3 to 11
- Native Area: southern Mediterranean regions
How to Grow Artichokes
Because it often takes two years for artichokes to flower, they are normally planted as container plants that are sold in their second year, or from established root crowns. In zones 9 to 11, artichokes can be planted in either the spring or fall. Gardeners in cooler climates should do their planting in the early spring, just after the last frost passes.
Plant them in soil that is light and well-drained: Slightly sandy soil (think Mediterranean) is ideal. Artichokes are large plants that should be spaced at least four feet apart—six feet is even better. Artichokes that are grown as annuals, or where the tops will be killed back by frost, will not get as large and can be spaced a little closer.
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. It is especially important when you are growing your artichokes as perennials to take the time to amend your 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 need a lot of water to produce tender flower buds. Water them deeply and frequently. 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.
Harvest the buds for eating before they develop into thistle flowers. If you are growing them as annuals, cut them down to ground level after flowers have faded, and cover them with mulch for the winter.
Artichokes grow best in full sun. They can tolerate some shade, but the flower buds will suffer somewhat.
Artichokes prefer a sandy, well-drained but fertile soil. A pH slightly on the alkaline side is best.
Water frequently and deeply—one to three times a week. This will keep flower buds fleshy and tender and develop a strong root system that will keep the plants upright.
Temperature and Humidity
This plant prefers warm weather that is relatively dry, such as that found in the Mediterranean and 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).
Use a balanced vegetable plant food every two weeks throughout the growing season.
Growing From Seed
Start seed indoors, at least eight weeks before your last frost date. Harden the seedlings off before planting 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 10 days to temperatures of about 50 degrees Fahrenheit or a little lower.
If you try saving seed from your artichokes, they may not grow true, producing plants that vary greatly from your original plant. You will have better success with purchased seed that has been grown under controlled conditions.
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 non-ideal growing conditions.
- 'Imperial Star' is widely adaptable, easy to grow from seed, and bred to be grown as an annual. Imperial Star is the variety recommended for gardeners in Zones 6 and colder.
- 'Purple of Romagna' is a tender Italian heirloom favored by chefs.
- 'Violetto' is Italian heirloom favored for producing dozens of small side shoots.
If you want to grow artichokes as perennials, adapt your over-wintering methods to your 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 cooler: You can try the method given above, for Zones 6 to 7, or you can pot up your plants, move them to a dark spot that stays cool, but above freezing, and water occasionally throughout the winter. In the spring, move pots back outdoors after all danger of frost, and either replant in soil or continue to grow in containers.
Whatever your zone or method, remove all the covering in spring, as soon as the soil has thawed and no hard frosts are expected.
Artichoke plants should produce for about three to five years. At that time, you should notice side shoots at the base of the plant. You can lift, divide and replant the new shoots.
In ideal conditions, like the coastal areas of the Mediterranean and California, established plants will produce buds periodically throughout the year. However, 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.
Artichokes are best when cooked lightly and prepared simply. They can be roasted or steamed and served with dipping sauce.
Using Artichokes as Ornamental Plants
Artichokes are often described as architectural plants and one look at a tall, branching specimen will tell you why. Since few animals attack 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.
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 cut back on 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 noticed. For severe infections, use a fungicide labeled for edible plants, such as neem.