I feel it just need a whole designing.avoid accept a idea this time,other time feel other suggests good.a style design,some clear "S"curve or line,evergreen bush,trees,vine will suppress weeds mess.
some vegetable life is short,it often make mess.interplant some shrub,fruit tree avoid it.
you could test your soil PH,maybe don't remove lava rock.

To begin at the end, the ground cover is a juniper, and it might be that one or two bushes are dead while others remain alive. I love junipers but in this scenario you could use better landscaping, so maybe it's no loss. Start by cutting out the dead stuff, see if it is a separate plant or part of a living one, and see if the remainder survives. You might have a root competition thing going on where the plant cannot keep itself watered or nourished.

With the back yard, think about what you would do if you forget about the fence that is there. Would it help to change the location and type of fence, for example? Does your property extend beyond where the fence is? And is there any hope of filling in the moat or is it part of the topography for drainage or just the natural curve of the land?

For weed control you need to figure out what weeds you have and how they spread. If they are spreading by runners, mulch won't help; you have to follow the roots and rip them out. Or use chemicals, of course, but mechanical means work too. If they are spreading by seed, then mulch will eventually cut down on regrowth. Covering the ground with plants that you want, whether trees or perennials, can also help.

Your photos are too close up mostly to give me a real feel for the lay of the land. But assuming it can't be changed, do you know what your fence bylaws permit you to build?

KarinL

Unfortunately, there's not much we can do with the fence. The fence can't be any higher and we live in a HOA regulated neighborhood. Everyone has the same fence. There's about a foot or two past the fence on the east side before you hit the sidewalk. On the north side, we couldn't move it since we share the fence with the neighbor.

Filling in the moat is probably not possible. It's about 3-4 feet deep and 12 feet wide. There's a retaining wall made out of railroad ties, but I get the impression it's more the case of the natural lay of the land and the original developers put in the railroad ties to prevent erosion. I suppose it may be possible to bump out the retaining wall to where the fence is and put the fence on that, but I would image the cost to be quite high and I'm not sure the HOA would go for that.

I understand that a Previous Owner raised and levelled the backyard adjacent to the house by installing a retaining wall. What I don't understand from the photos is the layout of the lower level (your "moat"). Is it on one, two, or three sides of the backyard? Which direction does the back of the house face?

You say the moat is 12' wide; what about the other area(s)? I see some photos that seem to show a much narrower space between the retaining wall and the fence. Just how narrow are the other areas?

The stairway which accesses the moat seems to lead to the narrower part of the moat rather than to the 12' area. How does that work? Would it be more convenient to add another stairway on the 12' side of the moat?

Here's why I say you need a stair directly to the 12' section: it seems to me the obvious thing to do to solve the low-fence issue is to plant a row of narrow trees and/or shrubs in the moat along the fence. You'd want to use trees/shrubs that -- unless very narrow -- could be limbed up to allow easier access to that narrow space: you'd still need to prune them, weed, maintain the fence, etc.

Are there any HOA regs that would prevent you planting trees close to the fence?

But re. the trees, keep in mind how their shade will affect your veggie beds in the wider part of the moat.

Remove the current clutter and junk trees in the moat. Start now: they're only going to get bigger and require more effort to remove later. Plus their absence will give you a better feel for the space and its potential.

Wow - you have a serious challenge here. I can see why you are perplexed as to how to handle it. I do love your description of the moat, though, very good way to explain it.

I would guess that a lot of the moat stays shaded almost all day because of the shadows cast by the retaining wall and the fence. One big question is ... what do you want in that area? Do you need it for anything - like an area for the dog to run?

If it was my moat & I was happy enough with the size of my backyard such that I didn't need to moat-area for any function ... I would do the following:
Kill the stuff that is there. Either physically remove it to kill it, or use an herbicide (brush-be-gone) that kills down to the roots and then remove it.
Ensure the ground that is there has decent drainage & pH. Then I'd add some compost (3-5") and mix it in.
In any area that has enough sun, I'd plant some fruiting trees/bushes. Blueberries, pears, cherries, apricots ... whatever the soil can support & I like to eat (which is all of those except pears).
I'd buy the world's best weedblock fabric (the cheap stuff is cheap for a reason) and use that plus a ton of barkmulch to minimize weeding/maintenance around my trees/bushes.
In 3-8 years I'd stand on the retaining wall and pick fruit that is at eye level, instead of climbing a step-ladder. And I'd be patting myself on the back for how relatively easy it is to use bird netting to protect my crop, since I can reach the top of my trees much easier.

Now if your HOA prohibits fruiting trees, then maybe you just use some "street trees" in the moat. I'm talking about trees that top out at 20-30', they'd keep a nice canopy at the right height (just above the fenceline) and give you some privacy in the summer. I'm not sure if redbud or red japanese maple or sandcherry would do well in your area. But I'd look for trees with color - either blooms or foliage - so they stand out.

Good luck, and remember that this doesn't all have to be completed right away. It's perfectly normal to attack these kinds of projects in stages and have your plan evolve over time. Unless you are on HGTV, no one's yard looks great after just a few weekends of work :)

What's the moat for? Does it collect stormwater and so it's flooded for 3 months out of the year? That will impact what can grow in it. Even if it just provides a place for stormwater to sheet flow to a drainage area, it can impact what can be grown as far as what can stand up to fast moving water for a certain period of time.

Also, what's at the base of the moat? We're assuming it's just dirt but it could be a few inches of dirt over concrete. If that's the case, you may need to grow stuff in containers.

And also no, there is nothing there worth preserving as far as I can see. If you do end up tearing out a shrub or perennial with nice flowers, they're easily replaceable anyway. But i really doubt that anything there was planted on purpose. So you can clean it up and start from scratch with a clean conscience.

Tanowicki has some good points.

KarinL

To provide more details:

I call it a moat, but it has no moat-like qualities other than it's a large ditch area. It doesn't retain water (CO is pretty dry anyway...) and the base is dirt topped with lava rock (thanks for that, previous owner).

The backyard faces NNE. The moat is only on two sides: the north, where the fence is between me and my neighbor's yard, and the east, where the fence is about a couple feet from the sidewalk and street.

The north side moat is skinnier than the east side. The north side is about 4 feet wide and is mostly dominated by those 3 bush-like monsters. Closer to the east side of the moat it is more clear, with that giant lamb's ear and random weeds. The north side is about 12 feet wide and 20-25 feet long. Where the monster bushes are on the north side, it looks like a previous owner tried cutting them down based on some of the stumps I saw last winter, but they have come back with a vengeance.

The east side does get decent sun during the summer, at least enough that my veggie garden looks good. I'm an avid food grower and would like to make use of that ditch space, since I don't have a ton of room in my backyard.

I've also played with the idea of growing trees down there, but I'm not sure which ones would work best in this type of scenario. Another option I thought of is potentially growing large bushes, trees or a vine on a trellis sort of thing up on top of the retaining wall area, which would block the patio/upper part of the backyard from the road, but not completely shade/take up the moat. Again, I'm not really sure what sort of plant would work well in accomplishing that...

Couple of questions:
- The lava rock: do I need to completely remove it? There is a relatively small layer covering the ground.

- Killing off the sucker trees: is my best bet poisoning them? We already tried manually cutting out the ones in the east side ditch where the veg beds are (you can kind of see a main stump in pic 6 near the left bed), but it was extremely pervasive and we couldn't remove everything. Lo and behold, stuff is popping up again this year.

Thanks!

Bump.

I could really use some guidance on what to do with the lava rock. Do I just have to bite the bullet and remove it by hand, or is there a way to cover it up? Any ideas are appreciated.

Help on how to remove the bushes and their stumps/roots without making it poisonous or risky to grow fruit trees there would be great.

lava rock: rake & remove by hand. Could use in a path, but will always annoy you in a flower bed.

Find out where the gas, electrical & water lines are before you begin work removing the bushes.

juniper bushes (from your pic): No doubt about it it's going to be heavy work to remove, but can be done.

Rent a chipper to make mulch for gardens or pathways. Leather gloves & coveralls or long sleeves/pants as well as eye & ear protection as you use a chain saw to make smaller pieces of the juniper. You'll have to dig out the stump & roots to chip those, too.

Fruit trees would grow fine as long as long as you improve the soil & water them.

"Find out where the gas, electrical & water lines are before you begin work removing the bushes."

GREAT advice.

"On the north side the moat continues, but there are 3 large bush things that are swamping the whole area. However they don't grow large enough to block the neighbor, and they look all spindly and terrible in the winter."

I like your raised beds but that ground shrubbery looks like it has taken over the yard. It looks old and unhealthy.

Instead of breaking your back trying to dig it up yourself, why not hire someone with a backhoe (etc), tear out everything and start over again?

Removal of everything is trickier that people tend to realize. Removing rocks from soil: you can try Lee Valley's rock rake, or you can build a big soil sifter, or you can just shovel the rocks+dirt into disposal. Find out what options your municipality has, but if you separate the lava rock you may find a taker on craigslist (list it for free, obviously). You could also put it in the bottom of a raised bed for drainage, perhaps?

Woody plants, make sure you have the right tools. Loppers, hand saw, long pruning saw... I usually stick to these manual tools but there is a time for power tools too, or hiring people who use them. If you can't dig the roots, and often you can't because they extend all the way to China, at least the roots of my flowering quince did, you have to just keep after the shoots for a number of years. I still have shoots of quince coming up after... jeez, it must be 6 years now. But it will die, it must, if leaves are not allowed to live long enough to feed the root. Your junipers, bless them, won't sprout from their stumps, I don't think.

Once you remove herbaceous weeds, keep the soil covered with something - mulch, a tarp, newspaper - so weeds don't resprout before you do whatever you decide to do with the space.

KarinL

Removing rocks is a PITA. It's one of the things that has kept me from tackling my backyard...I have horrible 1960's white landscape rock. And tendonitis. I honestly think we'll deck over it eventually. Until then...I'm thinking mulch edged with (largish)stones hauled out of our creek...

As to removing the shrubberies...I saw a guy using a weed wrench on invasives on the conservancy land near my house. The thing was BRILLIANT. I want one. (We discussed them here years ago...hadn't realized how awesome they were until I saw one in use.) You have to buy them online...I've linked the site. I'm lobbying for one for Christmas. Just need to decide what size...

Here is a link that might be useful: Weed Wrench

That is one cool tool! Wish I had had one when we were digging out the previous owner's bamboo fourteen years ago! I imagine, though, that I could find something to use it on if I try-ha!

As to the op's issue, I think planting trees once you clean out the moat would be fabulous. Tou will feel as though you are living in a tree house once they grow and you won't see your neighbors either. What could be better?!