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January 20, 2013

HOW TO GROW ARTICHOKES FROM SEED AND HARVEST IN ONE YEAR

Artichoke seed must be sown early, and mid to late January sowings result in plants large enough to
endure the neccessary cold 'vernalization' temperatures required for 2 weeks in April, which is a trick that
 ensures a good crop in the home garden.

Raising Artichokes from Seed

The lure of home grown artichokes drives many to try growing their own. The truth is, artichokes are not an easy crop,  they take up alot of room and the results are usually poor in most parts of the world. Those large, commercially grown green globe artichokes that many of us are familar are primarily grown in a coastal microclimate, the cool, Monterey coast of California for instance, just south of San Francisco, where most of our commercial artichokes come from.

You've undoubtedly seen artichoke seed for sale in seed catalogs, and I think many are curious about possibly growing a few, especially since they start with the letter 'A', I think I get more mail about How To Grow Artichokes than any other vegetable. Home grown plants can be rewarding, but one must follow directions strictly, as temperature is key throughout their life. There are times when artichokes want to be warm, and there are times when they want to be cold, and if you mess those periods up, you will just end up with nice, prickly thistle plants and never see a flower bud. Using some of the newer seed-raised varieties that have come into the market in the past decade or two. Don't be discouraged, you can grow them -just follow these directions precisely, and as late January and early February (right now - go order them!) is the time to start, here I share how I grow mine.






RootTrainer pots are great for tap-rooted plants like artichokes

Choosing the right variety

Artichokes are true perennials, even the ones sold as 'New Annual Forms' are, but the difference between named varieties is important if you live in most of the northern US. Forget about growing the so-called heirloom varieties (the violet ones such as Purple of Romania, Violetta Precoce or the green variety Green Globe) as they are all warm weather varieties, and they will not perform well in northern gardens. You will need to seek out varieties that can be raised from early sown seed, and that will form buds within the same year. I suggest seeking out IMPERIAL STAR ( available from Johnny's Selected Seeds and from Seeds of Change) as well as the purple variety OPERA ( also from Johnny's). NOTE: If you want to grow Cardoons, this is also the time to sow your seedlings, following the same methods.


RootTrainer pots can be tricky - since they do not lock, the pots fold up and retain their shape only if the entire flat is filled with pots.  One must fit the entire set of pots into the tray before filling with soil. They unfold when you are ready to plant easily, which reduces root disturbance. 



ARTICHOKES AND TEMPERATURES


In the past 15 years, new annual varieties of seed-raised Artichokes have been introduced for the home gardener ( primarily for those who live in the north), but before undertaking such a crop, there are a few things to note. First, artichokes require some homework on your part for there are specific needs which must be met - and most of these needs are based around temperature and timing. Seed must germinate at a certain temperature ( outlined at the end of this post), and something called 'Vernalization' ( a short, fake winter that you must expose young plants too in March or April), is essential, as it tricks the plants into thinking that it has passed through two springs, and that this year is the time to form flower buds.
( I am simplifing, but you get the idea - think 'forcing bulbs').

Artichoke seeds are large, which makes them easy to sow. I presoak them for 24 -36 hours


ARTICHOKE ARE TAP-ROOTED, WHICH MEANS....


Even though Artichokes are challenging, they can be rewarding (as the best challenging tasks usually are). There are some helpful facts to know about, especially with the physiology of the plant. Artichokes are tap-rooted plants, meaning that they form very deep roots, even as seedlings. As most tap-rooted plants dislike any root disturbance, it makes sense to start seeds in very deep pots to reduce and twisting and turning in the pot.

A root that has turned and twisted in a seedling pot or flat can only spell disaster when you transplant it into the garden. These young plants will sulk and ultimately remain sickly in comparison to their well-rooted kin, who had their long, graceful roots carefully tucked into deep, rich soil with a minimum of distress. You must not try to touch or even straighten out roots, or you will stunt the growth for a few weeks. My solution for tap rooted plants is simple  -  use a seedling pot called RootTrainers - a 6-8 inch deep system that allows tap rooted seedlings extra room where roots can run deeper than typical seedling trays or pots. Do a Google search for them, Toilet paper rolls will not work well, as the long growing season will result in decay well before seedlings can be planted out, but you may want to try saving your plastic water bottles, and cut the tops off.

Seed must be sown into warm soil, and seed germinates best at 75º. I place my pots under lights, with a heating mat where they will stay for 3 weeks before being moved to the greenhouse, which will be warmer by mid February. Artichokes are warm weather growers, but they are not fans of hot weather. Temps in the 70's are preferred, but the most important cultural note to follow is that seedlings will need a few weeks where they experience cold temps, called vernalization.

VERNALIZATION

When late March arrives, your artichoke seedlings will require some fancy temperature- related attention.  If one starts seed in January, the transplants will be ready to be planted out by the end of April, but they must be vernalized first - a fancy term for exposing plants to considerably cold temperatures for a few weeks - recent tests by Oregon State suggest that the idea vernalization could be exposing plants ( seedlings) to temperatures at about 40º F for 2-4 weeks to achieve proper vernalization ( other studies suggest that seeds can be vernalized if moistend, for 4 weeks and 35-40º F, but exposing seedlings is easier).

MATT'S ARTICHOKE 101

Growing Artichokes from Seed is easy, just be sure to do the right thing at the right time

Here is my method:

• I first pre-soaked for 24 hours to soften the seedcoat
• Seed is sown 1/4 -1/2 inch deep in RootTrainer pots in mid-January
• Seed tray is placed under lights with bottom heat at 74º F. until seedlings emerge ( 10-14 days)
• Seedlings are transferred to a heating mat in the cold greenhouse after a month indoors, were temps near the roots are kept at 75º F but air is maintained at 50º.
• Seedlings are fertilized bi-weekly to encourage strong growth
• Plants are brought outdoors on cool days starting in mid-march, and only brought in if temperatures drop below 32º at night ( to a porch - one must not bring them back into the warm greenhouse once vernalization has begun, for plants must believe that it is winter in northern California for at least two weeks - keep temps below 40º - it's not as hard as you may think, use a cold porch).
• Plants are set out into the garden in rows that are 3-4 feet apart on May 1.

OTHER JANUARY SOWN VEGETABLES


January also means that other seeds are being sown. Celery, onion, leek and shallot seed is being sown this weekend.


Pelleted onion seed makes for easy sowing. I place 2 -3 seeds per cell, and then place the onion flat under lights
on a heat mat as onions ( and leeks) germinate best at 75º F. Once germinated, they will be relocated to the greenhouse
where they will grow on at 55º. Under light is best, as when lights are turned off at night,
the drop in temperature is also helpful.

STARTING HOME ONION, LEEK and CELERY SEED


Onions, leeks and celery are the first seeds that I sow in the new year, best sown in late January. These are crops that require more than 8o days to reach maturity, and in my New England garden they really need 90 or more days. If you want large - I mean super large - onions, then forget about growing them from onion sets, which frankly, is a 1960's way of growing onions. Seed grown onions are easy, and the finest way to achieve success. Leeks  and onions both must be sown early, and gown cool to warm once they have germinated with strong light, ( under lights or in a greenhouse) to get pencil thick seedlings that can be transplanted into the garden in late April.

Celery seed ( pelleted) is also sown early. These seeds are sown in a community pot, as they can handle transplanting easily. In a couple of months, they will be transplanted to cell packs where they will grow on until late April, when
they are planted out into the raised bed.



5 comments :

  1. I have often admired the statue forms of the Artichoke. Your detailed method and summery are now making their way to my poly tunnel. I can now make a start.
    So inspiring Matt.

    ReplyDelete
  2. Thanks for the growing tips. Unfortunately I don't have any space to grow artichokes in my vegetable garden at the moment, but I am tempted to grow a few (or perhaps cardoons instead) as unusual ornamentals.

    Thanks also for the reminder about onion seed! I always get impatient to start sowing seeds as soon as we begin the new year, but I tend to forget about onions as I usually grow them from sets. I think I'll experiment with growing from seed this year!

    ReplyDelete
  3. Lots of good information in this post. My artichoke seeds are just starting to sprout and I'm putting them in soil today. I'm experimenting with growing them indoors (I don't have a greenhouse and Colorado winters are too cold), so I'm going to try to vernalize them in the cold air from slightly open windows. Hopefully it goes well!

    ReplyDelete
  4. I was reading at another site that the hot summers of Florida might be hard on artichokes. Is that true? If so, I might need to re-think: we're hotter and more humid than Florida. Any suggestions? I was considering planting in partial shade.

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    ReplyDelete
  5. Anonymous3:30 PM

    I planted two Globe starts last spring and mulched heavily through our Northern Arizona (7b) winter. We had a couple of nights that got below 12 degrees even.
    They survived and look great this spring. I'm keeping fingers crossed for some home grown organic Artichokes this summer. We are warm and dry through June but then we get monsoons for several months of cooler temps and high humidity...hopefully the chokes like it.

    ReplyDelete

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