g'day,

i would do it much the same way as starting a new raised bed, don't look at the 2 acre big picture just start at one end and work your way through, you are coming into your winter dormant period so use this in your favour as the weedy type plants will slow in growth.

use plenty of newspaper or cardboard and heaps of hay type mulch.

len

Here is a link that might be useful: len's garden page

I agree with Gardenlen. One thing you could do if you're concerned about materials spilling over is get some temporary stakes and pound them into the ground around the interior (or exterior for that matter) perimeter of each bed and wrap the whole thing in inexpensive chicken wire (maybe 1 foot high) to keep the mulching material contained. Lay your cardboard/newspaper and a layer of mulch which should deprive most of those weeds of sunilght long enough to kill them.

Chicken wire may not be the most attractive and it might have to be left up for several months to let the cardboard/mulch do a sufficient job but once everything's dead you can remove the fence and the mulch and then plant into your beds. The cardboard by that time will probably be mushy enough you can just dig it right into the dirt as you plant. Mulch would really benefit the plants though so if you are able to leave it in place too by that time or dig it into the ground all the better.

Another alternative is to just dig out a layer of dirt a few inches thick from the beds so you have room to lay cardboard/mulch without fencing it off first. Depending on the soil and types of weeds that may be labor-intensive but it would probably look better. You'd also be digging out some of those shallow-rooted weeds in the process which would help with your problem. Find some obscure corner of the garden to pile all that dirt/weeds in to use in the future if you need it.

Good luck with your project! Danielle

Check out The Nature Conservancy's website for info on battling invasives. I would hand pull english ivy it is hard to kill with light-deprivation alone. For black plastic or cardboard, etc. to work you might want to first mow everything down flush to the ground and then apply the mulch. If you reclaim one piece at a time you need a deep trench barrier to keep plant bits from the wild sections from growing into your cultivated sections.
There is also herbicide but I don't want to start a debate today.

I too agree with Len, and to add to what he said: Don't try to boil the ocean. 2 acres of raised beds and paths is a lot for a single person to tend. Start with the beds closest to the house and work out from there.

Blackberries and thistles will push their way through even the thickest layer of mulch, but most other weeds will succumb to the lack of light. So if it were me, I'd put a thick layer of straw or bedding hay down on the beds. You know how straw/hay peels off the bales in the form of "books?" Well, put books down as a mulch on all of the beds - don't fluff it up, just leave it as "books." That should squash 95% of the weeds in the beds proper and it won't blow away in the winter. Then buy yourself a good pair of gloves and be prepared to yank those blackberries and thistles as they appear. The hay/straw will compost in situ, thereby improving the soil.

As for the paths, I use pea stone on top of landscape fabric. I like the look of it (in fact, gravel paths are pretty standard in French potager gardening, which is the style my meager efforts attempt to emulate). It's also pretty cheap... the pea stone was called 3/8" round brown stone at the quarry, and it was ridiculously cheap, at like $3 per yard or some crazy thing like that. Roll out some heavy duty landscape fabric, pin it down at the edges, and start shoveling on the pea stone. Looks nice, low maintenance, and cheap. I do have an occasional weed take root in the gravel, but they're easy enough to pluck out.

Good luck!

-Diggity

Sounds like a massive undertaking. I would remove the top 6 inches of soil from each raised bed, taking as many of the roots of the invasives along with it. If you can compost this soil and kill the invasives, that would solve some problems.You can reuse the soil later, maybe next year. If the exposed soil under the top 6 inches is good, turn it, loosen it and add fresh composted soil and rejuvinate the soil. You may find some great soil down there. Mulch heavily. Any invasive that appear, pull them up by the roots as you see them. You must get the roots of the invasives out or you'll have an uphill battle.
Or, you can remove all the soil in the beds and put down newspaper and start over unless you are willing to use herbicide for a one-time clean out.

I'm sorry if this sets off a storm of protest, but I'd use Roundup. I don't like Roundup, and I use it very rarely. I hand paint Johnson grass myself. For one person to tackle 2 acres of invaded raised beds, I'd spray it on--with care. I'd spray a strong solution on very lightly, trying to avoid any dripping off. Pick a very still day. The main problem I have with spraying Roundup on 2 acres is how tempting it will be to rush, to get careless, to overspray.

One application might knock things back enough to allow hand weeding to finish the job, but again, if it were me I'd make a second application to missed spots or resistant invasives.

I'd give it a mere week to dissipate, and try to rejuvinate the soil life with manure, compost, and compost tea.

It's a radical solution, but it's a radial problem.

I think Patsy has a realistic approach to the problem, no, we dont like to use round-up., but theres times you just have to bite the bullet to get a hand on the situation, and start fresh.

When we bought this property in 1988 about an acre around the house had been originally planted with Juniper about 6 feet apart. After about 10 years of renters the juniper was five foot high and mixed with blackberry. poison oak as well as seedling oak and madrone trees. We cleared it all out mechanically hauling away eight 20 yard truckloads. We are still at this date fighting the blackberry and poison oak regrowing from massive root systems. Now with the landscaping installed we cannot use brush killer or roundup which would kill everything. I only wish I could go back to the beginning and kill all plant material,AND THE ROOTS, before hauling it all away. Al

If this is a sunny spot and there are no existing plants you want to preserve, solarization may be your best option. Yes, it will kill pretty much everything, including many microorganisms, but they will come back (especially if you amend the soil generously with compost once you start gardening). Basically you cut everything down, then cover the beds with CLEAR plastic and let it cook in the sun for several weeks. The good news is that this is an easy, no-chemical and low-labor way to kill weeds in a large area; it will even kill many of the seeds that are lying dormant in the soil, which are the real problem with controlling weeds. You will still have to keep after the weeds, because every time you till or otherwise disturb the soil it will bring them to the surface--but it's a start. The bad news is that this may not be a good time of year to do it; late spring and early summer are best to get the most sun and the most heat (but in zone 9 that may not be as big an issue).

Here is a link that might be useful: Soil solarization

You DO have a massive job and I agree that round up is probably the only realistic solution for the nasties. We have an overgrown garden too and it is only possible to do parts of it. This year, I bought a small electric lawnmower and use it wherever I can in the veggie garden, between the rows, chopping off errant raspberries, etc. It has kept a lot of weeds down to the point that this year, I can expand my "working veggie garden". The lasagna method works well smothering an awful lot of weeds, I used cardboard under the layers but it sounds like this is going to be difficult too. Is there any chance you can hire students in the springtime, or get volunteers to help at the start of the year so that you can get a handle on it?

Start with a good, reliable soil test. Contact your local office of the Univesity of California USDA Cooperative Extension Service about having this done. They do not do soil test but can direct you to labs that will. Many times "weeds" can be controlled simply by getting your soil in balance. Also dig in with these simple soil tests
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer you soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
to get a good idea about the soil you have and what you need to do to to make it into something good and healthy so you can grow strong and healthy plants with less competition from "weeds".

Here is a link that might be useful: UC CES

Wow, thank you all SO much - a ton of great advice here. I was overwhelmed and feeling pretty defeated, but y'all have got me inspired now to try again with different, smarter approaches that provide a lot more leverage. Time to get out there and get to it :) thanks again everyone!!

I agree with Gardenlen about doing a bit at a time. I also agree with kimmsr that a soil test is in order for you.

I have trouble with the idea of herbicides. I realize that there are probably some situations (poision ivy and oak) where they may be the only option but I've seen too many people misuse such things.

What I would probably do personally (though it is kinda hard to tell without seeing the boarders on the raised beds) is choose a section of the garden and pull out the boarders, dig out any of the plants not killable by solarization or smothering. Mow everyting in that section low, and then start with the solarization in the spring or... Smothering right away, laying out lasagna gardens where you want the beds and wood chips or other slow to break down mulch for the paths. (the idea of putting some root/rhizome barriers down between the still to be done area and your freshly cultivated area is probably a good one. The right type of material can probably be pulled up and moved as you work your way along the garden.)

As to putting the boarders back in place, well I've found that boarders tend to protect weeds from being pulled up by the roots and make you less likely to re-arrange the garden. I would only use them if you can be fairly certain you kill off those weeds. The only raised bed boarders I'm actually using in my current garden are small ones that two people can lift up from around the bed if weeds become serious enough to require complete re-working. My experience with garden boarders at my grandmother's house (where most of the boarders are rocks and driftwood) is that it is impossible to pull the wild roses, grass, or other weeds out by the roots so you are essentially reduced to cutting them off all the time. This might be ok if a somewhat wild/soft feel is desired for the garden but with your invasive plants you might want to use the rock boarder materials for something new.

You are going to need huge amounts of organic materials no matter what you do. Start collecting/stockpiling cardboard, newspaper, leaves, compost, mulch, grass clippings, and whatever else you can find. Definitely turn a section of that garden into a composting area.

Good luck.

Why not take each of these ideas and use them on different beds?

Use roundup on one, soil solarization on another, cardboard on another, removing and composting the top 6 inches of soil on another, thickly mulch with hay on another, etc.

Document each one and come back here to give us the results and your opinions next spring.

Hamiltongardener, that is a fantastic idea. I'll do exactly that, and report back... it'll be interesting to see how this experiment turns out!

I am a big fan of experiments to see what works best. I've got several going on in my garden right now.

A couple of thoughts:

1. A soil test certainly won't hurt but may not be necessary. If this was once a well-maintained garden, the soil is probably already pretty good. Going to weed (i.e., lying "fallow") in many ways would improve the soil, especially if the weeds were left to die and decay in place over the years. But...

2. The soil is going to have a huge number of weed seeds. Many of these will stay dormant until they are brought to the surface by disturbance, which weeding, tilling or planting will do.

Whatever method you use, there will be 2 parts to it: getting rid of the existing weeds, and controlling the weeds that will spring up from dormant seeds. This was why I suggested solarization--it won't kill all those seeds, but it will kill some of them, especially the ones closest to the surface (which is where most of them will be if the soil has not been disturbed in a long time). Mulching helps immensely--many weed seeds respond to light so mulching will keep them from germinating in the first place--but mulching 2 acres will be a huge job.

I agree with everybody else that this is going to be a lot of work and doing it a bit at a time is probably your best option! And by all means try a variety of different methods--half the fun of gardening is in experimenting!

I have faced BIG projects twice before. Once was 2 acres of bermuda grass in a date palm orchard. the other was 5 acres of anything and everything. One thing is for sure, take it a piece at a time. Get a bit completely clean, start gardening it, and then move on the the next and add more over time.
Roundup would certainly be the fastest and very effective, but it is WAY not organic. If you want organic, I rather like the solarization plan. I tried it on a small section and it worked. I went with large sheets of dry wall as weed barriers for most of the 2 acres of bermuda grass, but since you have stone borders, that won't work for you. Things will grow out of the edges.
Solarization with large, full sheets of clear plastic seems like the winner for a large scale project like yours. Be sure to use heavy mil plastic that will withstand some plants trying to grow up through it at first, along with wind and time. Drape over the stone and overlap even in the walking paths so that everything is covered. Don't cut the time short; make sure you leave it on long enough. Use a weed whacker, a heavy hoe, and a machete, to chop everything down before you start covering with plastic.
Since you are in California, I'm guessing the grass it bermuda grass? if so mulching will NOT stop it, but you will have a worse nightmare trying to get the now VERY happy bermuda grass out of all that mulch. Been there... ohhhh did I do that.
Good luck!

1) So you know the base nutrient and soil pH levels.
2) So you do not add "stuff" to your soil that it does not need, but that you do add "stuff" to your soil that it does need.
3) So you do not add to the pollution of your environment.
4) So you do not spend money on "stuff" you do not need.
5) So the yields from the garden are really optimal and the plants you grow are not bothered by insect pests that are more attracted to plants under stress or that are unhealthy because their diet is wrong.

Here is a link that might be useful: Why soil test