Overwintering Globe Artichokes: Protecting or Lifting the Crown

Wet kills more crowns than cold does

Established globe artichokes shrug off light frost, and in a mild climate they stand through winter with only their outer leaves damaged. What they do not survive is sitting in cold, saturated soil for weeks. The crown, which is the thick fleshy junction of shoots and roots at soil level, rots from the inside, and the plant that looked fine in autumn simply never comes back in spring.

That changes the priority. Row cover and mulch are useful, but drainage is more useful. A plant on a low ridge in free-draining soil with a loose, airy mulch has a far better chance than a plant packed in wet straw on flat clay.

First-year plants are the vulnerable ones. Their crowns are small and their roots shallow, and they can be lost in a winter that an established four-year plant ignores completely. Give the young ones the protection first if you are short of material.

A crown that has rotted feels soft and hollow when you press it in late winter and smells sour when cut. A crown that is merely frost-damaged is still firm and pale inside, and will usually reshoot.

Cutting back before the cold sets in

Once cutting is finished and the plant is winding down, clear it. Spent flowering stems, collapsed outer leaves and anything yellowing all come off. Left in place they hold water against the crown all winter and provide slugs with a home right where the new shoots will emerge.

How far to cut back depends on the climate. In a mild region leave the healthy inner leaves standing, since they carry on working and shed rain away from the center. Where hard frost is expected, cut the whole plant down to about ten to twelve inches (25 to 30 cm) so you can mound and cover the crown properly.

1. Cut spent flowering stems to ground level Take every stem that has finished cropping right down. Hollow stem stubs left standing funnel rainwater directly into the crown, which is exactly where you do not want it.
2. Remove damaged and yellowing leaves Pull or cut away everything that has collapsed or gone yellow, and clear the debris from around the base. Do not leave it lying as a mulch; it rots against the crown.
3. Cut the plant back if hard frost is expected Reduce the whole plant to ten to twelve inches (25 to 30 cm) where winters are cold. In mild areas leave the healthy inner leaves standing instead.
4. Draw soil up around the base Mound three to four inches (8 to 10 cm) of dry soil or grit over the crown. This is the single most effective piece of winter protection and it also lifts the crown clear of standing water.
5. Clear slug shelter from the surrounding ground Slugs overwinter under old leaves and boards and then eat the emerging shoots in early spring. Tidying now saves the first flush of growth.

Do not cut back while the plant is still green and actively growing in autumn. Wait until growth has clearly stopped, or you provoke soft new shoots that will be killed by the first hard frost.

Mulching the crown so it stays dry

The purpose of a winter mulch on an artichoke is insulation without wetness. Loose, airy material that traps air and sheds rain works. Dense, water-holding material packed against the crown does the opposite of what you want and is how well-intentioned gardeners rot their own plants.

Apply the mulch once the ground has cooled, not while it is still warm. Mulching too early keeps the soil warm, delays dormancy, and gives slugs and rodents a comfortable place to spend the winter next to your crowns.

In a wet climate, a cloche or a sheet of board propped over the crown to keep rain off does more good than any amount of mulch heaped on top of it.

Lifting and storing where the ground freezes hard

Where winter temperatures drop well below 10F (-12C) and the ground freezes deeply, mulching is not enough and the crowns are lifted instead. This is more work but it is reliable, and it also gives you the chance to inspect and divide the plants.

Lift after the tops have been cut back and before the ground freezes. Dig a wide root ball, keep as much soil on the roots as you can, and store the plants somewhere cold but frost-free and dark, in barely damp material. They are dormant, so they need almost nothing: just enough moisture that the roots do not shrivel and enough cold that they do not start into growth.

1. Cut the top back to about a foot Reduce the plant to ten to twelve inches (25 to 30 cm) so it is manageable and there is little leaf area left to lose water in storage.
2. Lift with a wide root ball Start the fork well outside the leaf spread. Artichoke roots go deep and wide, and cutting them close to the crown loses the reserves the plant needs to restart.
3. Store cold, dark and barely damp Pack the roots in slightly moist sand, bark or old compost in a box, and keep them at just above freezing to about 40F (5C). A dark shed, cellar or unheated garage suits them.
4. Check them through the winter Look at them once a month. Cut out anything that has gone soft, and mist the packing material lightly if it has dried out completely. Wet packing is worse than dry.
5. Replant in spring after the hard frosts Put them back out once the ground is workable and severe frost has passed, at the same depth as before, and water them in. Take offsets at this point if the crown is crowded.

Keep a note of which stored plant came from which position and how old each one is. A four-year crown is not worth the storage space, and knowing the ages tells you what to discard rather than lift.

Restarting in spring

Pull the mulch back as soon as the worst cold has passed and growth is about to restart. Leaving it in place through a mild spring keeps the crown damp and cold, delays the plant and invites slugs to the new shoots.

Check the crowns for frost heave. A plant lifted proud of the soil by repeated freezing and thawing dries out at the roots and can die in spring despite having survived the winter. Firm it back down and draw soil around it. Then feed heavily, because everything the plant does this year starts now.

Write down which plants came through and which were lost each winter, along with how cold it got. After two or three winters you will know exactly how much protection your site actually needs.