stones and moisture

[Hagakure]

i have some stones on top of my cacti and im wondering why i need em. i chucked em on because a lot of pictures i have seen have them.

my concern is when i had just plain soil there was a large area for evaporation and the soil would dry out very quickly. now moisture seems to be locked in more with the stones on top.

i guess i can just water them less now but im wondering whats better and what other people do.

the cacti i had with exposed soil are looking so healthy and green now im wondering if i should say, well if it aint broke dont fix it. its good to let them dry completely to avoid root rot and it seems easier to do this with just soil on top.

but there may be some benefit to rocks on top i dont know about.

or perhaps the layer of rocks is too thick on my plants.

[mu!]

How fine/small are the stones?

I use a mixture of pebble-type stones and bigger ones (roughly the size of a marble) a few cm's wide around the base of my cacti when I want to keep them stable (ie, after a transplant). I doubt course stones would trap the moisture too much, or even fine stones, unless you're really packing the shit down.

A layer of compost/mulch covers the top soil of my cactus pots, which I think would trap a LOT more moisture than stones, and all mulch covered cacti are doing fine. I still add the course stones on top, but now just for ornamental purposes

If you're fretting about your plants dying from too much moisture trapped by the stones, just but the stones on one of your (least favourite? ) plants and see how that goes over a few weeks, just to test it.

Whatever you do with em, good luck

Edited December 17, 2006 by without

[nothinghead]

without - I agree that stones will retain less moisture than potting mix/compost.

My understanding is that the stones are there to support the plant so it does not move around in the pot, potentially damaging roots in the process. Also that a layer of pebbles/gravel around cacti such lophophora allows water to flow down to the deeper roots, retaining water at these lower levels where it can be absorbed while leaving the "neck" of the cactus relatively dry.

[SaBReT00tH]

my fav and main reason for rocks/pebbles on cacti are for watering!!!! You can water them without all your expensive coarse sand/perlite mix spilling out everywhere and exposing the roots!!

[bit]

Never had a problem with stones here, but I've only been growing cacti for about a year. I did notice this spring that many cacti surrounded by pummice (2-5mm) rather than decorative stones abot (10mm diameter) pupped. None surrounded by stones pupped.

[Ace]

That was probably just a coinky-dink Bit. I have a little pedro stump that has started pupping this year and it is surrounded by decorative gravel/stones from hamiltons world of cacti (purchased from Kmart/bunnings). It all depends on how vigorous your plants are and if they are in the mood for pupping. Mine only had to because i chopped the top half off to form another plant (which is also taking off quite well and also dressed with the same gravel). All up to the cacti i think people...

[Alice]

i've just planted out all my cacti into a "cacti and succulents only" garden bed. figured they'd be happier in the ground. i've put a thick (up to 7 cm) layer of crushed terracotta mulch over the whole bed, not just for aethetical reasons and stabilization, but also in an attempt to suppress weed growth. weeding this garden is quite hazardous to say the least

i've dug around abit, and while soil moisture is retained more, i don't think it will be a problem as the rocks heat up heaps in the sun and this probably assists at least the upper layers of soil to dry out.

in terms of particle size, most of the crushed terracotta pieces are >1cm diameter. one thing i did notice was that their was lots of terracotta "dust" coating the pieces, which seemed to form a slurry when wet. this may be something to watch out for as it could potentially seal the soil and hinder evaporation. i started to wash each barrowload to rinse off the dust, but will a touch over 500kg of crushed terracotta, it was taking forever so i only washed about 1/10 of it.

the bed is raised and has fairly free draining soil, tho i'm still a little worried how they'll go over winter now that they're in the ground and heavily mulched with pebbles. it's alot of cacti to loose if they rot.... but hey i've got a few years left in me so i can always start the collection again if i loose them

[apothecary]

The whole point of the stones is to promote dryness at the soil surface, whilst not interfering with moisture at deeper levels.

An inadvertent advantage when rocking button cacti, it stops the neck 'sucking up' small bits of wet dirt into its crevices which can sometimes lead to rot.

Edited December 20, 2006 by apothecary