That is a good question. I have often wondered. I use cedar mulch.
Mine just builds up about an inch a year. I don't mind. I am 42 now so , when I am 70 I suppose I will worry.
Samuel

I just keep piling it on and remove some of the excess soil that builds up due to the composting of the mulch when the beds get too high. I use this rich soil as fill in low spots of the yard. You can slowly make raised beds using landscape timbers and adding to them as needed. The higher soil in the beds helps with drainage.
Even with adding more every year it should take quite awhile to build up too much soil in the beds.

Karl is the expert, and I respect his advice.

I take care of roses at my residence, and roses at a small municipal rose garden. I have assistance from others at the public rose garden.

In my own yard I just keep piling up the wood chip mulch. I am not as good as I should be at covering roses every year in my own beds. So occasionally I lose rose bushes and need to dig a new hole, and consequently my mulch layer thins in the area of the digging. I haven't removed any mulch in my rose bed. But I haven't added so much it is overly thick either. It should be made thicker.

At the municipal garden we piled up the wood chip mulch for aboout 5 years. We never took it out. It breaks down, and builds up the soil. It was about six inches thick. This year my principal partner removed the mulch, and put on a new mulch. I thought it a good idea to remove the old, and start new. He is retired and I am not. Thankfully I have help. Our municipal roses are healthy and in general fairly good looking rose bushes.

I have observed another public rose garden in Dubuque. It appears that they use a mulch of partially composted leaves. It is dark, thick, and provides a very attractive contrast in the rose bed. In early spring I have seen their mulch layer removed completely. They have about 800 roses and a lot of volunteer manpower. They appear to reapply mulch in the spring. They have an impressive rose garden at the Dubuque Arboretum.

There are different ways of handling mulching that are effective. I cannot pretend to advise what is best. More mulch is better than thin mulch, as a general rule. I've given you three approaches, and they all work. I personally like what we have done as far as mulching in our municipal garden best of the three, and it probably emulates most closely Karl's approach.

I quit using the cedar and cypress mulch, it doesn't seem to ever break down and dulls my shears. If i use any mulch at all, i will use cotton burr compost. I never worried much about buildup because i think the wind blew most of it away anyway. I just got finished putting rocks around my roses so i can weedeat without hitting them, and figure that should make a good mulch that won't blow away and offer some trace minerals into the soil everytime it rains.

I apply composted steer manure from Home Depot at about $1 a bag over the mulch. The mulch degrades to soil very fast. The worms love it.

Maybe just add less? If you use chopped leaves, don't use the bark and vice versa...

Also make sure you don't have a 'mulch mask' where the mulch is so thick that the water (rain or other watering) can't penetrate to the roots. We are having this problem here in the SE. Conventional wisdom says to mulch to preserve soil moisture, but at this point the soil is dried out and much of the rain is absorbed by the dry mulch before it gets to the soil/roots.

francie12, you said "the organic matter in the beds is building up to the point of too much."....are you worried about a height issue or a soils quality issue?

Garden soil still needs to be soil, not pure compost. Organic matter somewhere between 5 and 10 percent is considered very good. How's this for a hypothesis: soils have different concentrations of organic matter. At some point, some sort of balance is reached, and all we need to do is sustain that level of organic matter. Mature garden soils or soils in locations with high levels of organic matter don't need compost so much as mulch - - something a bit more coarse, a bit slower to break down, to suppress weeds, to protect the soil from the sun, keeping the soil bioactive and releasing nitrogen into the soil. The ideal mulch shouldn't build up: it should break down but not so fast you're hauling it constantly.

New garden soils can "process" very large quantities of mulch applied to the surface. But compost can be overdone: too much organic matter can be too much of a good thing. In the case of bark products, you can see when the mulch has thinned and needs to be supplemented.

There are several articles about organic matter and gardens in Linda Chalker-Scott's Horticultural Myths. She points out that gardens aren't like farms growing food crops.

Balance is everything.

Here is a link that might be useful: Horticultural myths: excessive organic matter

Berndoodle,
I've found I can plant in soil that is composed only of composted material such as mulch or leaves. It seems to support very healthy growth. In addition its water holding capacity is greater than plain soil as is drainage. I wouldn't hesitate using pure compost both as a regular soil in the yard or garden or as a potting soil.
The area we live in had a lot of truck farms growing vegetables for local markets. It originally was swamp or river bottom and contained a very high percentage of organic material. Unfortunately, most of this land is now growing houses with the rich top soil hauled away and sold back to the home buyers who have been left with a sterile subsoil.

Thanks for all the thoughtful and informed answers. Something to be said in favor of removing a layer of old mulch--it could take away eggs or larvae of pests (sawfly, I hope?) or traces of blackspot affected leaves. I'm very fortunate to not have a too serious problem with blackspot, but I'd love to eradicate every last sawfly stage. If removing old mulch will help with this, I'll definately do it. A layer of bark chips will be thicker than a layer of chopped oak leaves, and there's something about the look of the chopped leaves that I like--and they shouldn't build up to quite the heights of bark .

Is there any harm in the bud union (most of my roses are grafted) getting progressively deeper under ground as the soil builds higher? I know it is a plus in my colder climate to have it well under--I planted them four inches deep to start with--but they are probably six inches deep now, and getting deeper.

As the bud union goes deeper more roots form on the canes above it and below the soil surface. Eventually the bud union become unnecessary as the plant is growing on it's own roots. Feeder roots stay within the top 6 inches of the soil. Anything below that are anchor roots.

Excellent! Thanks, Carl.

There is a significant disadvantage to using bark chips. They won't stay in a bed. They blow with the wind.

The ideal mulch shouldn't build up: it should break down but not so fast you're hauling it constantly.

LOL-that's me-the constant hauler. My beds chew up about an inch/month of shredded green waste from the landfill(including things like old pallets).

You could always skip a year of adding mulch. Maybe just fluff up the old stuff with a rake if it looks untidy.

Hi, Karl, I agree that lots of things will grow in pure composted material. And I don't want to overstate the case against compost: it is fabulous in the garden, especially for those of us who have to plant our gardens on new lots of exposed subsoil. I can imagine that with your summer rains and flooding, faster drainage is always a good thing. I also like the idea of raking the mulch each season to remove pestiferous flora and fauna. But...I don't have the resources to replace annually, either in terms of muscle power, time or even will.

The questions are: are we expending unnecessary resources when the same plant will also grow in soil with 5 to 10 % organic matter, and are we polluting the surface water and groundwater with excess nutrients. I'd take that river bottom soil any day! I don't want my plants in pure compost. I want them to make a living with their roots deep in the soil.

Did you read the article about the excess nitrate soils test with organic matter of 21%? The problem exposed was excessively high nitrates along with all other major nutrients also too high. Where rainfalls are high, these excess nutrient leach into groundwater and surrounding streams. Where rainfalls are low, plants can burn.

I think it's a case of using just enough, not too much, and moderation in all things.

Here is a link that might be useful: results of excessive nutrients in surface water

This year I'm adding pine bark only to the thinner areas that I have. I am just raking to refresh the older thick areas, or throwing a barely there skim coat over it to make it all blend in. You CAN get it too thick. I find if it is too thick, it colonizes noxious weed seeds easier.

I think it would be a shame to waste mulch by removing the old stuff to turn around and replace it with new.

Sandy