May be you can plant some shade-loving steppable plants (carpet plants)in between the flagstones.

I speak from a different climate so can't say if your patio will hold up if done as you propose. However, time is a real constraint and as I have had to conclude many times over the years, you can only do what you can do.

If the patio is improperly laid due to the wide gaps, and you think you might eventually like to fix that, I would just ensure you do nothing irreversible now. If you can dig up or chip up the stone dust later to relay the patio properly, then your solution might be a fine interim approach. As may be evident, I've never worked with stone dust.

I have a patio with wide gaps between stones and as I've said on a nearby thread, my problem is that the gaps are ankle-twisters because they aren't properly filled. So do make sure you pack and fill them adequately!

Irish moss is a sun-loving plant, isn't it? If you want to try plants one more time, there should be some that will work. In my zone, I've been successful with Ajuga, Oxalis, and Asarum. These are not flat, but they can bear some foot traffic. They also fill in quickly, being vigorous. The down side of their vigor is that in my installation (on my hellstrip) their roots are starting to push up the adjacent slabs a bit after 5 or so years.

KarinL

Thanks for the tips, Karin. I think our patio was laid properly--it isn't completely even since the stones are natural, but nothing is loose or jiggly. I probably would only plant something very flat; we get a lot of foot traffic, and have a table on the patio, plus I have a toddler who would pull up anything too tall. This picture posted by another gardenweb gardener shows approximately what I'm going for with the stone dust.

Here is a link that might be useful: {{gwi:38947}}

The flagstones were probably laid on either sand or stone dust. The mud has filled in over the years. Also, weeds can and will grow in straight stone dust.

So what are you really trying to accomplish here? I have a lot of moss growing in the cracks, but the patio also requires a certain amount of weeding.

I know that there will be some weeding, but we get an unmanageable number of weeds in the patio by mid-summer and I'd like to cut down on the number. I'd also like to get rid of the mud so that it looks cleaner, so that there's less dirt and mud that encroaches onto the flagstones, and so that my toddler can sit on the patio without getting dirty. Do you think the stone dust idea will accomplish these goals?

IME, not really. Instead of sitting in mud, the toddler will be sitting in wet stone dust. Maybe that's an improvement. I think the big difference as far as the weeds are concerned is that it takes a year or two before the seeds start building up in the stone dust. After that, it's just as weedy.

Is there a drainage issue? It almost sounds like mud is getting washed across the patio.

You can carefully hose or powerwash out the mud and other debris that has accumulated over time and then replace it with stonedust. If you do this, you want to be careful not to wash out any of the base underlying the flagstone. Sweep the stonedust into the spaces, let it settle than do it again. It actually takes a lot less stone dust than you would think. This will result in a much cleaner look- like the picture you posted. If there is a drainage issue, the stone dust will also get out onto the flagstone, but it would be less messy than mud. While you are at it you may want to wash the flagstone, sometimes in the shade it will get a mossy sheen on it- unless you like that look.

Thanks again for all the input, everyone! I decided to go take a picture so that you could see what I'm talking about. The cracks are almost totally filled with weeds (and some grass) right now because I'd given up on weeding in hopes of doing my stone dust project. But you can imagine that if I pulled up the weeds, it would be all dirt there. Our soil is clay and compacts very easily; the mud doesn't really wash all over the flagstones, but when you walk on the patio your shoes might get dirty. Since it's clay, it takes forever to dry out and is almost always in a wet or damp state. It's a layer of compacted dirt at least a couple of inches deep, not right on the surface. I'm just going for a cleaner look, as some of you have suggested. We have a very small yard, so the patio has a big impact!

The second picture is really of the lawn and just shows the very edge of the patio, but you can see its relation to the yard.

If anyone has more suggestions or feedback on the idea of scraping out the dirt and adding stone dust to the patio, please keep commenting! I appreciate it.

{{gwi:38952}}

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Here's one more from early spring, before the weeds emerged. (Head removed to protect the innocent.) You can see how the dirt in the gaps is not so attractive.

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Go to a mason's supply yard with pictures andask about polymeric joint filler.

Thanks, laag. I googled polymeric joint filler and came up with something called EnviroStone that sounds like it could work. Anyone have experience with that?

I haven't heard of polymeric joint filler being used between flagstones. My understanding is it is best used on narrow joints - pavers or concrete - but that doesn't mean it can't be done. Laag always knows his stuff so if he suggests it I'd definitely look into it. I'd check it out with the EnviroStone's 800 number - they may have some tips.

From your lawn photos it looks like there is no edging to the terrace. This is allowing the grass (and weeds - not that I'm suggesting your lawn has any!) to migrate between the flagstones and could be part of the problem. It would also mean that anything you use to fill the flagstone gaps will migrate to the lawn eventually.

Can I edge retroactively, or do you have to put down edging before you lay the flagstones? I am OK with a little bit of migration; it doesn't have to be perfect, just cleaner than it is now. Some of the grass that's between the flagstones is because we overseeded and got some on the patio.

I'm a lurker here who is a homeowner and not a pro, and has little design knowledge/ability (which is why i lurk!), but I have used EnviroStone! We just finished laying a 500 sq ft flagstone patio ourselves with it and are very pleased. EnviroStone is designed for wider joints (the same company has different products for narrow joints).

For your application, I think you would need to be able to dig ALL of the mud out of each joint. There is a PDF you can download online with the EnviroStone specs/instructions and it says that you should not have any other filler material in the bottom of each joint, otherwise that can wash out from under the EnviroStone and make the joint unstable. I don't know whether they just say that to make you buy enough product to fill all of the joint depth, but it made sense to us, so we followed that.

We had a base of 3" compacted crush-and-run (like crushed stone, i think), topped with 1" of granite sand (we got a landscape company to do that part). Then we levelled the flagstones in the granite sand, and then we filled in the joints with EnviroStone and watered down. So far (only 2 months), it looks great and the stones feel solid. It was also easy enough to install to be a DIY job (easy for me to say, as my brother and husband did it all!).

I think having a solid/level base is important -- especially in the North where you get more frost movement (we are in Atlanta).

I am adding a pic of our patio to show how wide our joints are. We did this as a DIY project, so I'm aware that it doesn't look like a pro job!

Hope this helps -- if you decide your base is good enough and you can dig out all that mud, i think EnviroStone would be a good option.

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Thanks so much, mayland! Your patio looks really great, and I appreciate you sharing your experiences. I'm glad you came out of lurking! I will definitely look into EnviroStone.

Thanks everyone for your suggestions. You guys are awesome. I'd love to continue to hear any more advice if people have other ideas.

Moss would also work. Many mosses grow in shady spots where grass won't grow. Very soft, very pretty, and when you decide to redo, easy to remove.