If you read our article from last week, you already learned about gathering your seed starting materials, including lights, soil, containers and more. You (hopefully) figured out your last frost date, and used it to determine when to start your first transplants (onions and leeks). This week we’ll talk about starting your next crop, artichokes, and how to “harden off” all of your seedlings in preparation for outdoor planting.

Artichoke seedlings

Artichokes are a perennial crop that can be grown as an annual in areas with cold winters. They should be started 8-10 weeks before planting outdoors—so if, for example, your last frost date is May 1st, they should be started between the middle and end of February. In order to produce flowers (artichokes), they need to be convinced that they are in their second year of growth. In other words, they need to be “vernalized”, or exposed to cold, to make them think they’ve experienced winter. One of our varieties, Tavor, requires less vernalization time than others, but it is still essential to produce artichokes.

Germination & Vernalization

Here’s a tip for success: before starting your artichoke seeds, put them in an airtight container in the refrigerator with a small amount of slightly damp peat moss. The cool, damp conditions will help convince your seeds that it’s springtime, and result in better, more even germination. Start artichokes according to our instructions, keeping the plants between 60-70ºF until two weeks before your planting date. At that point, move the plants to a cold frame or other cool, protected location. The goal is for them to experience some stress, with temperatures below 50ºF but above freezing for ten days. If the weather threatens to dip below freezing in that period, move them indoors until the frost danger has passed.

Taylor & Sarah in the High Mowing Artichoke Trials field

Bed Prep

Once you’ve moved your artichokes outside for vernalization, it’s time to prep your artichoke bed. Loosen the soil with a garden fork and incorporate compost, then dig a 6” deep trench in each row and line it with compost. Space plants 4-6’ apart over these trenches, in rows 7’ apart. After planting, keep an eye on the weather and cover your plants with row cover if frost or hail threatens.

Growing Tips

Anyone who’s grown artichokes knows that they’re a bit particular—they like cool (but not cold) winters, warm (but not very hot) summers, and moist, fertile soils. A good rule of thumb to make them happy all the time? Compost and mulch once a month, and provide a little shade from the hot afternoon sun so they don’t get too dry. With a little care and a little luck, you’ll be harvesting 7-8 buds per plant. And yes, you can grow artichokes in containers, but they’ll need to be BIG—ideally the size of a whiskey barrel or larger—and always kept moist for bud development. They make great ornamentals, and look beautiful in giant mixed containers with flowers like Sea Shells Blend Cosmos and our trailing Nasturtium Blend. The nasturtiums will help cover the surface soil in the container, keeping it cool and moist even in bright sun. And of course, if you don’t harvest the artichokes they’ll make giant purple thistle-like flowers that will knock your socks off.

A coldframe, like this High Mowing low tunnel, is a great place to harden off seedlings

Hardening Off is just what it sounds like—preparing your coddled transplants for the harsh world outdoors. (Note: this is for your other transplants, not artichokes.) Hardening off is simple to do, requiring just a little of your time and attention, but it makes a huge difference in terms of plant health and reducing “transplant shock”. About two weeks before your planting date, move your transplants outdoors to an area protected from strong wind. Leave them out for just an hour or two the first day, especially if it’s sunny or windy, and then bring them back inside. The next day increase the time they spend outside to 3-4 hours, and so on each day until they spend pretty much the whole day (and night) outside. The key to hardening off is to be aware of the weather and make sure your still-tender plants don’t get left outside in strong winds or torrential downpours before they’re really ready for them. You'll notice as the days pass that the plants will become visibly sturdier, growing thicker stems and producing more protective waxes on their leaves.

When it’s time to plant, the best time is on an overcast day, just before it rains, or late in the afternoon on a sunny day. If your plants are properly hardened off, planted at a suitable time and watered in, they should acclimate beautifully to the outside world.

Stay tuned! Next week we’ll look at starting brassicas and how to create a succession planting plan, so that you’ll always have the transplants you need for an abundant, extended harvest.

And if you missed it, check out last week's post, A Complete Guide to Starting Seeds: Tools, Tips and Alliums (Part 1)