Paula,

As a leading exponent (if not outright snob) of top dressing, the advantages are as follows:

1) keeping a plant's roots cooler (a little bit)
2) weed control (big!)
3) evaporation doesn't occur so quickly (also big!)
4) aesthetics (as you noted, but this is also big!)

I can't sleep at night well unless I have 4-6 kinds of top dressing - right now there are about 8-10 out there, but some top dressing hustle and bustle should happen whenever the opportunity presents itself.

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Heh, I just use the same grit that goes into the mix itself.

A top dressing may also spread moisture through the whole container. I read something here about the top layer of a mix drying out and refusing to rewet because it couldn't effectively take water from below, but I can't figure out the search term I used (I do think it was one of tapla's posts). This was somewhat backed up by Google searches revealing that farmers sometimes plough up soil surfaces to dry them off and make them act as a kind of mulch, but I'd really prefer the original post to refer to.

At any rate, it would certainly slow surface evaporation from mixes that have no perched water to draw on and have a greater surface layer for evaporation.

I'll have to test this myself once the greenhouse is set up for overwintering...

@cactusmcharris What is the name of that GORGEOUS plant in the blue pot?!

I don't use top dressing, but I think the benefit of moisture retention depends largely on the type of soil you use. Topsoil, or soil with a significant amount of peat or other fine material, can be capable of continually wicking moisture to the soil surface where it can evaporate. Top dressing is coarse enough that is does not wick, so it keeps the moisture down, away from the sun and wind. But a gritty soil, like many use, does not wick moisture upwards very well. It is essentially all top dressing, so you may as well just fill to the top with more soil.

Top dressing definitely adds a finished look to most plants, though. Weeds I've never had a problem with, but it could help with that as well.

I have a huge tendency to overwater everything. So I put a lot of perlite in my succulent soil. Drains great and helps me sleep at nigt not worrying about having drowned my plants. However, the perlite rises to the surface and manages to get everywhere and make an unsightly mess.

Somewhere someone...I think I read it on this Board in a long ago post... said that you put coarse sand on the top to dress the top of plant off and help with the top soil. Then I had perlite and coarse sand everywhere.

In looking at everyones photos and in books, I saw all kinds of beautiful top dressing. I loved the look of some of the glass ones. Don't know if reflects the heat or not, but I got some green glass and it is beautiful.

So now I have soil, perlite, sand, glass, and the pots are full. Newbie mistakes I guess.

I have top dressed an cactus garden with crushed granit and xeric seeds that blow around my texas countryside do like to germinate in the mix so I am not sure if top dressing is a good weed control . In pots yes, but in an area, maybe not. Some seeds LOVE to germinate in it. Mater of fact, some xeric seed packages recommend a gravely surface for germination. The cooling factor becomes more important the hotter it is. At 112F and 8% humidity, it is important.

Pea gravel on top? Pouring is easier, I would think...

As I was saying, this might be a bit largish to use, but it held in the roots quite nicely of these ranging New World Crassulaceae crosses that just want to play the field.

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bonus pile of top dressing to be reused on the left

Thank you all for your help. I decided to try some pea gravel. After all it does look pretty good. When I went to my local Lowe's what I did find was much bigger than yours is Jeff. I added it to a few of my plants and I found it did make my plants pop out. I was tho surprised to find the rock got a little hot even on a mild day. I am now thinking of paver base or aquarium size which may be costly. I also may not be at the right store yet!

May I ask cactusmcharris: Is that a soup bowl with holes drilled in it turned upside down?

Again Thank you all, Paula

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Paula,

It's a decorative bowl that may have been safe to use as a food dish. It will make a great bowl to root cuttings in or have some shallow-rooted plants growing in and spilling over the edge of.

I hope I'm missing something, but those Echeveria agavoides (?) look overpotted - it is just an optical illusion? Is there more than an inch or two of space around the rootballs of those plants?

No more illusion. I went outside to look. 1" around and if I remember I had to shave a little off the root ball. It is one of my newer ones so I could add the pea gravel with out having to remove any added decoration. When I added the gravel to some Aloes they popped out but this Echeveria I thought it dwarfed. That is one of the reasons I was thinking of a smaller medium to use. I use bowls as lower wider pots are not available here. I took some other photos but photobucket is being a pain in my behind today. Have a great day. 9.11 Remembered. Paula

I use pea gravel and other top dressings to keep the tree rats from digging in my pots. The ones without top dressing almost always end up dug up to make room for a walnut or to get at the roots and eat them.

The fact that weeding is greatly reduced is a huge plus too.

Gil

Lots of my cacti are lime lovers - I can get marble (calcium carbonate) chips here in Spain, so I add a good portion of them to my mix. They also make a smart top dressing.

Top dressings are great. I like pea gravel, crushed granite (grit for roofing), screened decomposed granite, red lava (scoria) of different sizes. I imagine black scoria would look nice if used sparingly. Coarse silica sand looks good too. I can't bring myself to buy little baggies of material for $2 or $5 at club sales -- I prefer to buy by the cubic foot at least.

One of the most important roles of top dressing is to mechanically stabilize the base of the plant.

Another role for top dressing... if you use something inorganic like pumice, you can cover the base of the plant (eg, to cover flaws or make it appear less leggy) without promoting rot. Effectively you're just raising the level of the soil -- risky with some plants unless you use the right materials.

Take care and pay attention to your plants. I think I killed a couple plants by covering a grower's organic-rich mix with a top dressing that was too heavy (fine crushed granite). I think the crushed rock retained too much moisture and rotted the plants' roots (small Dorstenia gigas and Aloe pronkii, ouch!).

When I bought replacement plants (addict!), I tipped out most of the grower's organic-rich mix and topped with small pumice instead of fine rock. Crossing my fingers, this should work better. Wish me luck!

Ilovetogrow, I think your plant was dwarfed by your choice of top dressing for two reasons, Size of granuals, and contrasing colors of the pea gravel. For small mid tones, One needs to look for a contrasting uniform color top dressing. The red of the bowl distracts the eye away from the plant also. The reddish brown and green recede in the confusion. also the pot is large as stated above. OOPs that is more than 2 reasons.