I used to coordinate an organic Community Garden in a park which belonged to the City of Berkeley, California. We had to fence the garden in (with barbed wire on top) because of theft of the food crops and damage by roving dogs. We also had to lock up the tool shed because of theft of the tools by non-gardeners. (They'd sell the tools at the local flea market.) Most of the people gardening were middle-aged folks. We tried to get children interested, but we weren't successful. We encouraged a mix of flower and produce gardening because of the pollinators and beauty brought by flowering plants. Cottage gardens are gorgeous! We held potluck meetings once a month (in the garden) to share info, educate each other, and air grievances. Each gardener had their own plot. We discouraged the planting of perennials, unless it was something like an artichoke, which would produce food year after year. Once in awhile we organized work parties. Peer pressure got most of the gardeners to show up. We did our own compost. We had to build a large bin for that. We also had to do intense weeding a couple of times a year because nearby Bermuda grass, growing in the park, would encroach upon the garden. I doubt a rotating schedule would work. Someone will always be flaking out for one reason or another. However, if gardeners have their own plots, they will likely feel more responsible. Sharing amongst gardeners would happen naturally, if there is abundance of some items. If you wish to discuss more in depth, I can be reached at lornaf@zianet.com Please put "community garden" in the subject line so I do not inadvertently trash the Email as spam. Lorna

I suppose you could just grow Trilliums and other plants whose natural lifespans are 40+ years. That way you wouldn't have to worry about genetic diversity. I think one of the reasons you might not be getting the kinds of answers that you may be hoping for is personality/psychology related rather than plant ecology related. Most of the gardeners I know are putterers - we like to mess around in our gardens, adding things, moving things, etc. You've described the opposite of that. Also, most gardeners I know appreciate the dynamic aspect of nature. Most of our property is woodland, and my family enjoys the natural progression - trees fall and rot, small trees grow larger, etc. We have fond feelings for the oaks out front that now shade the only possible place for a veggie garden enough we won't be able to grow tomatoes much longer. Because we enjoy watching things change, I can't imagine managing nature so closely we'd be worried about genetic diversity. But because you sound sincere, I've been trying to think about your idea. Climate change is an issue. To have healthy plants 4 decades from now, I wouldn't plant anything for which zone 7 is the hotter end of its range - who knows what zone you'll be in 40 years from now. Other factors that might cause change include your neighbors - our closest neighbor clear cut their yard a few years back. Fortunately, they left a small section of trees on the side facing us, or they would have even more significantly changed the light in a part of our woodland close to our house. Pests also can cause big changes. The Emerald Ash Borer and other pests are getting closer and closer to my area. Future problems with invasive non-native pests aren't something you can predict. Also, not all plants are good at naturalizing, or self-sowing. Are you planning to collect seed and grow specimens to replace ones that die? If you're not planning on helping things along, you're going to have to make sure you plant only good self-sowers. I don't know what kind of landscape you're envisioning, but some of those kinds of plants are good at getting seedlings pretty far away from the parent plant. You could move errant seedlings, but it sounds like you want to stay away from "hands on management." If you are planning on helping, and for the 10% area if you do plan to use cuttings and vegetative propagation, you'll need a nursery area. I also don't understand why you wouldn't have more than one of a species even if the population won't be enough to sustain itself? Look at any landscaping book - people tend to like the look of groups of plants, not single specimens. Unless these singletons are trees or shrubs, it might be harder to make things look good. Whups, no matter how hard I try, I seem to be thinking of reasons why your idea is a problem rather than ideas to help you, sorry! Why not be curious and just try it and see what happens? Surely you'll find that some of your 10% species work for your plan. Some won't, and you can replace those along the way. It's not like you'll be on a spaceship to Mars - it'll be possible to get different plants in 20 years. If you do go ahead with your idea, it would certainly make a unique article in a gardening magazine 20 or 30 years from now. Good luck! And I wasn't joking about Trillium - plants with longer lifespans would help your proposition work.

I asked some local growers - Johnson Grass spreads by rhizomes, so chopping it up or tilling in a cover crop just spreads it around - it's not as aggressive that way as bermuda grass but it's persistent. It is CRITICAL to keep the tops from doing what yours did, which is thrive and set seed. In fertile uncompacted soil, you have tertiary roots 20-30 inches down which are capable of sending up sprouts all summer. The vineyards use geese, which may be organic as heck, but impractical in a shared garden. They leave NOTHING behind that they think is edible. A "flame weeder" might work if you repeatedly use it on the new sprouts - the idea is to exhaust the root's stores of energy by forcing them to grow leaves faster than the leaves can resupply the roots storage. ==================== This OLD research explains the root development cycle and where to interrupt it: http://naldc.nal.usda.gov/download/ORC00000094/PDF They are in favor of repeated SHALLOW cultivation to force the roots to resprout to the point of exhaustion, and even (if you have repeated freeze-thaw cycles) shallow cultuvation in winter to expose and freeze the roots. They are also in favor of close mowing or grazing to keep the plants too small to support the big, deep problem roots, what they call the tertiary roots. ========================= If you are in the "organic" section, that limits your chemical options. You might kill it with repeated applications of "horticultural" vinegar (the 20% stuff, or a minimum of 10%) but it's nasty to use. Be sure to read the MSDS and wear appropriate skin, eye and lung protection. http://www.groworganic.com/organic-gardening/articles/help-johnson-grass  http://www.gardenguides.com/139610-organic-control-johnson-grass.html They claim this works: http://www.homedepot.com/p/Avenger-Weed-Killer-128-oz-Organic-Weed-Killer-Herbicide-Concentrated-AVGR-Conct-128oz/204336249 NOTE: the "organic" solution you see on Pinterest and other blogs, with vinegar, dish soap and salt is really bad for your soil and doesn't work worth a darn.

UPDATE 2020 JUNE I was planning to check the progress in May and then again in July, but all travel is off this year due to COVID19. So luckily for me, I have a close family member that has been checking on the project for me as well as pulling the ferns every couple of weeks to allow the other plants a chance. Another reality for me is that the deer on this island are overpopulated and will eat everything they can, which makes matters even more tough. In May I was sent photos of new growth that was popping up which turned out to be bunchberry dogwood, a species I didn't plant and that I have never seen in July. Then when my relative checked again in a couple of weeks, the ones that were initially there were gone and others had popped up. So i presume the deer eat thee every year and never allow them to grow to maturity so I don't see them in July. As of 2 weeks ago, out of the 75,000 or so seeds I planted, exactly one was positively identified, one of the Wild Lupine seeds has made it and is growing! Supposedly it is deer resistant so fingers crossed. I should have more updates throughout the year and will check in about the progress. One other good piece of news was that the small blueberry plant I dug up and moved to the area last September, has survived the winter and is growing fresh leaves. That's really wonderful news because I only watered it one time before having to leave, and now 9 months later it's alive and well. So I will be able to repeat this many times over now (whenever I can get to Maine) and hopefully in 3-5 years I can establish a very large area of low bush blueberries. It's been very dry in Maine so far and my hope is that the other seeds I planted are still waiting to make an appearance somehow. Presumed Bunchberry Dogwood The Blueberry plant I transplanted in september and survived (pic from this May) And here is my one confirmed successful seed (so far), the Wild Lupine (from June)