Artichokes are perennial plants in the south, and will grow more heads as they age, up to their maturity age of 5 years old. In the north, they are treated as an annual. If your area has hard freezes, consider keeping your artichokes in pots for the winter. Use rich, fertile soil, but artichokes can grow in almost any soil, as long as they are well-fed.
Start your seeds indoors in 3-4” pots under fluorescent lights. Seeds should germinate in 7-10 days indoors. Seedlings will need to start being hardened off (exposed to outdoor temperatures) about 6 weeks before the last frost date for your area. Plants need to be planted outdoors about 3-4 weeks before the last frost date, and need to be exposed to temperatures below 45ºF to be able to flower (if you don’t get the cold temperature, your plant might not flower until the second year). Space your plants 3’ apart at a minimum, but 4-6’ is recommended. When the seedlings are 8-10 weeks old, remove any weak seedlings that are not stocky with at least 2 sets of leaves.
Add nitrogen to your soil prior to transplanting, then side dress with a balanced fertilizer before buds form. Artichokes also need 1-2” of water per week, with well draining soil. During initial growth, artichokes need extra water to grow larger.
The “vegetable” part of an artichoke is actually the flower bud. These appear in mid-to-late summer and should be harvested when the bottom petals (bracts) start to open. Use a knife to cut the artichoke stem - leave about 3” of the stem on the head. Artichokes can be stored in the fridge until ready to be cooked. After the first batch, a second, smaller batch of flowers may grow. Purple varieties have sweeter buds than green varieties.
If you let the buds bloom, you’re in for a beautiful treat. Artichokes are members of the thistle family, and display a large purple thistle flower. If you want seeds, wait until the flower is spent and the stem to it has dried. Cut the flower from the stem and use a knife to cut the flower head open. Wear a pair of heavy duty gloves, as they are extra pokey after drying. The seeds are in the center of the head with a bunch of fluff around it. Consider cleaning your seeds outside.
If you’re overwintering your plants in the garden, they need to be cut back to the ground and entirely covered by mulch.
Artichoke isn’t usually bothered by pests, except for a few caterpillars that won’t eat enough of the plant to do it any real harm, but the dense foliage can make it a haven for other bugs to lay their eggs in safety. Check your plants for any egg clusters throughout the growing season.