I've had good luck vernalizing young Imperial Star artichoke plants in the refrigerator in past years. I think it's more reliable than leaving it up to Mother Nature, at least in Michigan's variable (wierd!) climate. I do it when they have about 6 leaves and are about 4 inches tall. If all went well, I got them sown on time (early March), germination was prompt, etc., it should now be early/mid May. I let them get a little on the dry side but not wilted, since moisture is the enemy in this operation. I like to dust the foliage of each plant with a little Gold Bond type medicated body powder -- the zinc oxide and plant essential oils are fungicidal -- be sure to get some down into the crown of the plant. Then, I wrap each transplant individually (note, no pot on these, I grow them in cell trays and just pull them from the cells) in a paper towel or napkin, and pack them into a big ziplock bag. Then, seal it up. This goes in the bottom of the fridge for 10-14 days. During this time, they will turn somewhat yellow, they will curve up in response to gravity, and when they come out, will look kind of sad. But, as long as they are kept reasonably dry, they won't rot and dry. It is a GOOD IDEA to pull them out every few days and inspect, so that you don't have a nasty surprise of rotten plants at the end of this process. If rot does start, pull off the damaged leaves, dust with more Gold Bond, and repack in fresh, dry paper towels. You could probably save some of the little packs of silica gel from clothing, shoes, electronics to throw into the ziplock to help control the moisture during this vernalization. After the 10 days minimum, pull them out, repot them into about 4 inch pots, water them well, and stick them in the shade for 24 hours to recover. Then, I put them in the greenhouse and really baby them for a few weeks. At this point, it's probably mid June, about Flag Day, and they need to go into really rich, well-drained, well prepared ground or very large containers (the rope-handled utility tubs are a great size and are relatively cheap and durable as planters). They like a lot of fertilizer and water (but not soggy soil, or they'll rot). You should start seeing blossom initiation in mid/late July or early August, and will get artichokes into October. This has worked for me in the past. Hope this helps.

I've grown them for 2o+ years...they aren't nearly as invasive as people think. Somehow(birds maybe???)...the seed does get scattered...but I have ONLY seen new patches of it spring up in disturbed ground...it never just volunteers in my vegetable or perennial gardens...but we had to dig a 40 foot trench for new water pipe..and the following spring..there it was!...same with when we had a guy come with a backhoe and dig a ditch a long side our driveway...but as far as it "taking over"...that is so far from reality..at least in my zone.

Common sunflower is usually found along roadsides or the edges of farm fields. It is an annual that seems to require bare or disturbed soil to grow. It isn't very common in the eastern US, but very common in some parts of the arid west. Not sure of its status in michigan, but I bet it occurs there in at least a few locations.

Well, I have never found this plant to be particularly difficult to control, overly agressive, or problematic. As I stated above in my posts, I have no real trouble controlling it by harvesting and eating the tubers. Blanket statements about what should and shouldn't be "banned" here, there, and everywhere really bother me. Some plants truly are invasive and problematic in many regions, but things should be evaluated on a case by case basis. And, if we took the attitude that anything non-native shouldn't be grown because it might potentially be invasive, North America problably wouldn't be able to feed itself, and our ornamental flora would be greatly limited. What really bothers me, though, is being told what I can and can't do in my own garden by others. The Michigan legislature, in its infinite wisdom, debated a bill a few years ago, in 2005 I believe, which would have made "possession," defined as having a plant growing upon one's land, whether or not it was there by intent of the landowner, of a whole number of "invasive" species punishable by fines of up to $250,000 and up to 5 years in prison. The fact that the vast majority of these plants, things like purple loosestrife, yellow flag iris, and Japanese knotweed, were already rampant in Michigan didn't seem to register with the geniuses in Lansing, most of whom wouldn't know an invase plant it it bit them on the (well, you know where!). A group of professional growers and amateur gardeners got together and were able to get this horrendous and stupid bill defeated. Had it been passed, as written, it would have turned hundreds of thousands of Michigan landowners into felons overnight. Endangered and threatened native plants should be preserved, but banning plants from gardens isn't the way to go about it -- time would be better spent cleaning, improving, and protecting the specific habitat of threatened natives and learning to grow them in cultivation to preserve the species.