Most container/potting mixes contain perlite or vermiculite and they are both great soil additives for containers. They improve drainage and improve root access to oxygen.

What is NOT a positive contribution to container mix is topsoil or any kind of dirt. ;) Adding it defeats the purpose of making a container mix by turning it into potting soil and so you have all the problems associated with trying to use potting soils in containers - poor drainage, conpaction, root suffocation, root rot, etc. Check out the many recipes for great container mixes you can find over on the Container Gardening forum here.

Perlite is a mineral so will break down but very slowly over time and no, it does not limit mix reuse tho generally container mix needs to be refreshed by at least 1/2 annually.

Hope this helps.

Dave

Yeah point taken, I noticed the absence of soil from a lot of the mixes I read about, and while the reasoning seems sound, its slightly off-putting to me to grow without soil. Also I have loads of old topsoil, buying in all that compost/perlite/peat to replace it is too much work & cost at this point

another reason I want to use my topsoil is that living in egypt give me access to nile-fed soil (tired and potted in my case), this should be some of the most historic soil in the world, right? fed by the nutrient rich silt runoff from the Mountains of the Moon, traveling across East Africa, replenished every year by flood, that's worth something isn't it? just the names should makes the soil richer

I guess this sounds pretty silly, good advice like "soil is no good for potting mixes" is met by stubborn resistance "but I like my soil..." But how about any advice to regarding using topsoil in potting soil? how to counter its problems? or have people just moved onto better mediums and don't bother with topsoil?

thanks for the comments though, I would be interested in hearing from anyone who doesn't like perlite

I love the stuff.

I've noticed no one seems to use it outdoors in gardens, unless I just don't know about it. It seems like it would improve drainage and be beneficial.

Some of it will eventually float up to the surface it is less dense than the rest of the soil. No big deal though.

I've used perlite outdoors in potting holes for plants that like a lot of drainage. There's nothing negative about using perlite. It's a natural substance. I've never heard of it breaking down, though.

kcchuck, unfortunately for our containerized plants, top soil (no matter how exotic the origin) turns into something less than desirable when used 'in captivity'. All of the great properties of a good top soil become null and void when you remove it from the 'system' of a working soil system. The functionality and performance changes dramatically.

SO! In order to create an optimum growing environment for our containerized plants, it's up to us to make sure that we aren't using anything that will muck up the works. The ingredients need to be coarse textured to insure rapid drainage and long lasting and large pore spaces. Top soil, compost, sand, and even peat (if it's milled very finely) can help create a cement-like substance in which our plants are not likely to thrive.

Perlite is a great addition to a good, long-lasting potting medium and can mitigate the problems that peat can create. I use conifer bark fines, perlite, granite grit, and Turface MVP as a growing medium. I first began using that combination for my bonsai about 20 years ago and decided to use it for everything. Much to my plants' happiness. If I were to suggest something simple for you, I'd encourage you to mix perlite and peat by a 50:50 ratio.