Green Man Publishing

Artichoke, Globe

Cynara scolymus

Introduction: Artichoke is native to the Mediterranean, where its flower buds have been a favored food since the time of ancient Greece. They are quite a unique vegetable, in that the part eaten is actually a part of the flower (the scales and swollen base). They are also relatively unusual in being a perennial.

Artichoke is considered to be one of the finest of all vegetable foods. I think it fully lives up to its reputation, no other vegetable is quite as decadently delicious when cooked fresh from the garden. This is somewhat ironic, when you consider that it is a kind of thistle.

Artichokes are quite nutritious, but you don’t usually eat them in sufficient quantity for them to be an important food source. Also the sprawling plants need a lot of space, so the yield per square foot is low.

Nutritional content: Artichokes are a fair source of vitamins A and C, as well as niacin and folate (the natural form of folic acid). They also contain a variety of valuable anti-cancer and immune-boosting phytonutrients,  including cynarin and luteolin.

Cynarin is not only a useful antioxidant with medicinal properties, it also stimulates taste bud receptors and actually makes food taste better.

Crop value: You don’t generally eat a lot of artichoke, so it tends to be more of a treat than a substantial food. It is actually a  highly nutritious food though and there is a lot of room for us to increase our consumption of these delicious and nutritious buds. Grow them yourself and you can live like a Roman emperor, stuffing yourself with artichokes every few days (well a little bit like one),

Ease of growing: In the right climate artichokes are pretty low maintenance and need almost no attention. They are perennial and can yield for up to 7 years, though the best hearts are usually produced in their second and third years. This is why they are usually replaced with new offsets every 3 years.

When growing as a perennial, artichoke needs a lengthy rest period of cool weather (anywhere from 10 – 50 days under 50˚F, depending upon the variety). It doesn’t do well if it is too mild, too cold, or too hot and dry in summer (though it may survive the latter by going dormant).

In very mild or very cold climates it can be quite difficult to grow as a perennial, but don’t despair, you can still grow it as an annual. This is more work and the harvest won’t be as big, but it can work out,

Climate: Artichokes grow best in a mild, damp, maritime climate, such as is found in coastal California. The cool growing weather means slower growth and higher quality buds.

If the climate isn’t suitable they won’t produce very large (or high quality) flower buds. The best approach to growing them is determined by your climate. In the ideal cool and mild climate they are planted in spring and harvested in fall and through the winter.

Though artichokes prefer cool weather they are not very frost hardy and won’t survive in areas with cold winters. Even relatively mild temperatures (28˚F) will kill the flower buds, while lower temperatures (especially when combined with wet soil) will kill the whole plant. In colder areas artichokes must either be grown as annuals, or the roots must be protected over the winter in some way.

Soil

pH 6.0-7.0

The best soil for growing artichokes is deep, rich, well-drained, sandy and slightly acidic. Drainage is particularly important in cold climates, because if the roots stay cold and wet for long

periods they will often rot (this is the commonest reason plants die over the winter).

About Globe Artichoke  
Seed facts
Perennial
Germ temp: 50 (65 – 70) 75˚F
Germ time: 7 – 21 days
Viability: 6 – 10 years
Germination percentage: 60 %+
Weeks to grow transplants: 10 – 12  

Planning facts
Hardiness: Somewhat hardy
Growing temp: 50 (60 – 65) 75˚F
Plants per person: 3
Plants per sq ft: 1 plant needs 9 sq ft
Days to harvest: 6 – 12 months
Plant height: 3 – 5 ft
Plant diameter: 4 – 6 ft  

Planting
Start: 6 weeks before last frost
Plant out: 2 weeks after last frost  

Harvest facts
Harvest period: 8 – 12 weeks
Yield per sq ft: 1 head
Yield per plant: 24 – 48 heads
Plants per person: 1 – 2

Soil preparation: Artichokes are a short term perennial, so you won’t be able to dig the soil again without disturbing them. Amend the soil generously before planting and if you are feeling energetic you might even double dig.

Because the plants are so widely spaced, you could amend the individual planting holes, rather than fertilizing the whole bed. Dig a large planting hole and replace half of the soil with compost or aged manure. You should also give them some greensand (for potassium), colloidal phosphate (for phosphorus) and kelp (for trace elements), or an organic fertilizer mix.

If your soil isn’t well-drained you should grow your artichokes on raised beds or mounds.

Planning

Where: These large plants need a lot of space for the amount of food they produce and this is probably the main reason they aren’t more popular. They are just too big for the intensive vegetable garden beds and are best planted individually in any odd vacant corner. You want to put them somewhere they can get as big as they want, without causing any problems. They work well as a border or low hedge for the ornamental garden.

In the ideal climate artichokes should be placed in full sun, but in hot dry ones they may do better with some light shade during the hottest part of the day. They should also be sheltered from strong winds, as they are also somewhat vulnerable to being blown over.

Don’t plant artichokes close to established trees or shrubs, as they won’t be able to compete. This is particularly important in dry climates.

When: In suitably mild climates the roots can be planted while they are dormant in late winter or early spring. In colder climates they should be planted 2 – 3 weeks before the last frost date (the soil temperature should be at least 50˚F).

To grow artichokes from seed you usually start them indoors in late winter, six weeks before the last frost date, An early start is particularly important if you are growing them as an annual, as this allows them to grow for longer and get bigger. This is important if you want to harvest flower buds before the plant is killed by frost (which you do).

Planting

Artichokes are usually propagated vegetatively from offsets. They can be started from seed quite easily, but this doesn’t breed very true, which means there will be a lot of variation in the offspring. If you must use seed, choose the best seedlings to grow on and discard the rest. In future years you can propagate your chosen plants vegetatively.

Growing from seed:

Indoors: Start the seed indoors in cell packs, soil blocks or individual 3˝ pots. If you don’t have many seeds, put one in each cell / pot,  if you have lots put 2 – 3 in each one and thin to the best plant when all have germinated. Artichoke seedlings grow quickly, so be prepared to transplant them into larger pots if necessary. 

Plant the seedlings out in their permanent position after all danger of frost is past and they have at least two sets of true leaves. The plants will grow rapidly once they get established in rich soil.

If any buds appear during the first year, they should be nipped off to encourage strong root growth. Obviously if you are growing it as an annual, you don’t do this.

Outdoors: If your climate is suitable you can sow the seed directly outdoors (½˝ deep). The best way to do this is to start them in a nursery bed and transplant them when they are big enough.

Vegetative propagation

What: Artichokes are normally grown from the suckers (offsets) that emerge from the old plant in spring. These work much better than growing from seed, as you can select suckers from the best plants. These are the plants that grow vigorously, produce the best quality buds, yield earlier and are most productive. All of the suckers  from the same plant will be genetically identical of course.

If you don’t have any plants to propagate from, you can buy them, or look around for a friend or neighbor to beg, steal or borrow from. Alternatively you can start from seed and then use the best plants for propagation in future years.

How: Suckers are removed from the parent plant as they emerge in spring. The normal practice is to dig down the side of the plant and cut off the emerging sucker (it may be up to 10˝ tall) with a heel of old root attached. Trim off most of the leaves (the minimal roots can’t support them) and plant it immediately in a well-prepared site, with the growing point at surface level. Alternatively you could plant it in a one gallon pot, or in nursery bed, until well rooted and then plant out.

These suckers are pretty tough and even if they appear to die, don’t give up on them straight away. I had a batch of plants that appeared to die, but they actually lay dormant all summer. When cool moist fall weather arrived they burst into life.

Buying plants: Artichoke plants may be found for sale in garden centers as either seedlings or dormant roots. You need to plant these whenever they are available (which is early spring in colder areas and all winter in milder ones). They should go in the ground at the same level they were in the nursery.

Spacing: A single artichoke plant will get bigger and bigger over the years and can easily grow to be 4 ft tall and 4 ft (or even 6 ft) wide. Obviously you need to give a plant this size plenty of room. The exact spacing may vary quite a bit, but usually you will grow them in rows.

Space them 36 – 48˝ apart within the rows, with 48 – 72˝ between the rows.

Growing as an annual: If your climate is too cold for artichokes to grow in the ground year round, you may still be able to grow them as annuals. You just have to use the right varieties and start them indoors early enough. You won’t get the big buds and big harvest of a mature perennial (and it will start later), but something is generally considered to be better than nothing.

Choose a variety that is adapted for annual growing and start the seed indoors 6 – 8 weeks before the last frost date, as described above. Plant out the seedlings 2 weeks after the last frost date. You want the plants to grow rapidly so you should pamper them with a regular feed (every 2 – 3 weeks) of compost tea or liquid kelp. The first buds should start to appear towards the end of the summer.

You don’t necessarily have to let the plants die over the winter, you can try any of the several ways of overwintering them. See Frost below for ways to do this.

Care

True to its thistly nature, the artichoke is a vigorous and robust plant that needs little attention once established. Its only real weakness is its minimal tolerance of cold.

Water: Though the artichoke is quite drought tolerant, it is important that the plants have evenly moist soil (at least an inch of  water per week), particularly when the buds are developing. Water is essential to produce succulent buds and those produced by drought stressed plants  may be tough and poorly flavored.

Don’t keep the soil wet all the time, as too much water can cause crown rot. Allow the surface to dry out between watering.

Fertilization: Artichokes are hungry plants and yield best when grown without any check in their growth. To achieve this they must get all the nutrients they need.

The plants are usually fed annually with a mulch of compost or aged manure. If the soil isn’t very fertile you can also side dress them with an organic fertilizer mix (in spring in colder areas, in fall in milder ones).

You can also give them a liquid feed of compost tea occasionally (they particularly like nitrogen).

Mulch: These widely spaced plants benefit from a layer of mulch during the growing season, especially when newly planted and there is a lot of bare soil between them. A mulch of compost is not only the main source of nutrients for these perennial plants, but it also helps to retain moisture, keeps down weeds and keeps the soil cool in summer.

Mulch is even more important in cold climates as it is used to prevent the ground from freezing in winter and so protects the tender crowns (see Frost protection below).

Support: Artichokes are fairly tall plants and can get quite top heavy, which makes them vulnerable to being blown over by strong wind. On a windy site you may have to stake them firmly to prevent this.

Thinning plants: After a couple of years of growth a plant may end up producing a dense cluster of 10 or more shoots. If all of these were allowed to mature they would get very crowded and would have to compete against each other. It is common practice to allow only 3 or 4 shoots (offsets) to develop into plants. The rest are removed in spring and used for propagation. These should be removed even if you don’t want them for propagation.

Pruning flower buds: It isn’t good to allow too many buds develop on a plant at once, as they won’t all reach full size. There should only be 3 – 5 buds (depending upon the size of the plant) maturing at one time. This ensures that each bud will grow to a good size.

Sometimes all of the lateral shoots and buds are cut off to leave only one main bud (known as the “king head”). This will then reach maximum size (in Italy these are very highly prized and fetch a premium price). 

Renewal: Commercial growers usually replace the plants after 2 or 3 harvests as their vigor begins to gradually decline after that. Home growers may do this too, replacing a portion (20% – 33%) of their artichoke plants each year. In this way you will always have vigorous young plants and will replace them all every 3 – 5 years. However if you prize low maintenance more than high yield, you don’t have to do this.

Problems

Frost protection: In cold climates artichokes will be killed by hard frost if not well protected. If you want your plants to survive the winter where the soil freezes hard, then you will have to protect them in some way.

The usual way to protect them is to cut off the tops, leaving about a foot of leaf (you can tie these together to protect the crown). You then cover the plant with a thick 24˝ deep mulch and then cover this with a cold frame or cloche. The latter is important as it keeps them dry (they often rot from too much moisture). If protected in this way they may survive down to 20˚F.

This protection should be removed after the danger of hard frost has ended in spring, but before the plants start

growing again. This allows the soil to warm up.

In very cold climates, you could try digging the roots in fall and storing them inside for the winter (what have you got to lose?). This is no more difficult than it is for Dahlias, simply lift the root as the leaves die back, cut off all but a couple of inches of stem and brush off loose soil. The best place to store them is in burlap sacks in a root cellar at 35 – 40˚F. Alternatively you could plant them in 5 gallon pots and keep them in a cold (but not freezing) garage.

Weeding: The plants should be weeded regularly when young and occasionally thereafter, as weeds may compete for water and nutrients. Of course the mulch will also help to suppress weed growth.

Pests: I haven’t found artichokes to be seriously bothered by disease or pests, but in some areas they can be severely affected. Slugs and snails appreciate the damp shade and numerous hiding around the plants and sometimes damage the buds. The larvae of the artichoke plume moth can ruin the buds. Aphids can also be a problem, but are easily washed off.

Disease: Crown rot (Botrytis) fungus can be a problem in warm wet weather.

Artichoke curly dwarf virus: This disease shows itself as curled leaves and small or misshapen flower buds. It is usually passed through infected offsets, rather than seed. If this becomes a problem remove all plants and start again from seed in a different location.

Harvest:

When: Perennial plants aren’t harvested until the spring of their second year. Then the terminal bud is harvested as soon as it reaches full size (2 – 4˝ in diameter) and while the bracts are still tight against the bud. Don’t

wait until they start to open up or they won’t be as good.

If you miss the right harvest time, you should still cut the over-mature buds, as this stimulates the plant to produce useful secondary buds. If a bud is left to mature it will cause the plant to waste energy making unwanted seed. After the terminal flower buds are removed, more will be produced on side shoots. In this way a single plant will produce a whole series of buds for several months (these will gradually get smaller as food reserves are diminished).

You should remove all of the flower buds as they are produced, even if they are not usable. If you leave any on the plant, it will waste energy making seeds and may even die.

How: The buds are cut with a knife, leaving at least an inch of stem. Handle them carefully after harvest as they are easily damaged.  In Italy they commonly

cut artichokes with longer stems as the interior is edible too.

Storage: The buds are best used fresh and start to deteriorate in flavor as soon as they are picked. They can be stored in the fridge in a plastic bag for up to two weeks.  A fresh artichoke is squeaky when squeezed.

If you are suddenly overwhelmed with artichokes you can freeze the prepared hearts (or can them).

After harvest care: After the last buds have been cut in early fall, the plant may be cut down to ground level and fertilized and mulched (compost does both at once). This will encourage it to regenerate itself and produce new buds for next year.

Seed saving: Saving artichoke seed is easy enough, but it is rarely done because they are normally propagated vegetatively. Allowing a plant to produce seed will weaken it, by causing it to divert energy away from vegetative growth.

Artichokes produce seed readily, as one flower can pollinate another on the same plant (though not itself). They will often self-sow if given the opportunity and volunteers can even become a pest.

If you live in an area where it is classified as a noxious weed, don’t let the seeds fly away.

Unusual Growing Ideas

Ornamental: If space in the intensive vegetable garden is limited you could put these space hogging plants in the ornamental garden. Their blue/purple flowers are quite spectacular, though of course they are rarely allowed to appear.

Containers: It is possible to grow artichokes in large containers and they can make striking ornamentals.

Wild garden: The artichoke is independent enough to be planted in a vacant corner and left to grow itself. You just have to give it enough care to keep it productive.

Varieties:

These can be divided into those that are used for perennial growing and those that are suited to growing as an annual.

Perennial artichokes

These can be divided into the large globe types and the smaller spiny types. I think I got the varieties right, but this is a confusing group.

Globe types – These are the familiar artichokes we see in markets.

Green Globe – The most important commercial American variety.

Imperial Star

Kiss of Burgundy – Tolerates more heat and cold than other varieties. It isn’t easy to find.

Spiny types – In Italy they eat a lot of spiny artichokes, which produce smaller buds and are often purple tinged. They look more like wild plants and are more tender and better flavored. 

Violetta di Albenga – Also has purple buds.

Annual artichokes – These varieties will produce useful buds in their first year. They need less exposure to cold weather (for vernalization) to trigger flowering.

Imperial Star – The most commonly grown annual type.

Grande Beurre – Very large heads, but isn’t easy to find..

Kitchen use

If insects get in between the bracts soak the bud in salt water for 10 minutes to get them out before cooking.

The traditional American way to cook an artichoke is to cut off the stem and the top of the head and then trim back the points of the scales. The heads are then boiled in salt water for about 30 minutes (don’t overcook them). They are then left upside down to drain and are served with butter or other dressing. They can also be steamed or fried.

The traditional American way to eat an artichoke begins by pulling off the individual bracts and stripping off the tender end with your teeth. When you have finished these, you are left with the best part at the end, the heart which is one of the most delicious foods in the whole vegetable kingdom. It was almost inevitable that such a sensuous food as an artichoke heart would be considered an aphrodisiac.

Any cut artichoke surface will turn gray, so they are often dipped in cold water and lemon juice to prevent this. You should also avoid cooking artichokes in aluminum or iron pans as it will discolor them.

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