raised bed question

[Joel143]

Hello everyone. I'm not new to cactus but am to raised beds which I am in the process of making. Have a question. My raise bed will be about 24" in depth. I've read I can't really amend my local soil and just place the raised bed on top due to I would be making a pool when it rains. My local soil is organic dirt which turns to more clay in the mix the deeper you go...maybe a foot or two depending. The mix I will be placing in the bed for the 24" above ground will be a fast draining mix naturally due to the rain in my area (southern Louisiana). My question or concern is the cactus will do great in the raised bed but what happens as the cactus grow and their roots continue growing into the local soil? With the local soil holding more moisture during the rain would it damage or rot the cactus? The bed will be in an area near my house that, to me, drains nicely but might stay evenly moist. A Cycad palm and some angel trumpet plants are in the area now which I will be moving.

Any info would be great because this makes me nervous. I would hate to lose the large cacti I plan to be placing in my raised bed. Cacti will include some cereus (Pachanoi, Peruvianus - both normal and monstrous form) Tricho's Tercheckii and Pasacana, some various fero's, some various Cleistocactus and Echinocereus. And a few others that can tolerate the winter months here (which I will give some protection).

[cactushobbyman]

I have some big cactus out in the garden and the root ball that I have seen so far doesn't reach 24" I moved a six foot Echinopsis spachiana and the root ball was greater in diameter than in depth, which was about no more than one foot deep. Just my experience so far.

[Joel143]

I have some big cactus out in the garden and the root ball that I have seen so far doesn't reach 24" I moved a six foot Echinopsis spachiana and the root ball was greater in diameter than in depth, which was about no more than one foot deep. Just my experience so far.

Thanks for the info. Give me some relief.

[MJPapay]

Most cacti are shallow-rooted.
Shallow roots allow them to soak up light rain, even dew if droplets seep down a little.
These roots can run a long distance - the bigger the plant the longer the run.
So you might instead worry about having enough root run for them, though I doubt that will be a problem except for very large plants.

You might be concerned about cacti with carrot-like storage roots, though I expect it would be a long time before they reached a depth of twentyfour inches.

[Cool Potter]

IMG_1632.JPG (136.42 KiB) Viewed 4379 times

I put in a raised bed garden two years ago. I'll attach pics. I found this year when moving things around a bit that the rocks I'd used for weather protection had become root protectors for the cacti. Roots from the taller cacti sought the cooler under-soil of the rock bases rather than go deep into the very poor soil below. The Cycad you have will transfer well if you water it for the first few days. Mine looks a bit knocked about but it was the heat in a glasshouse that did this not the transplanting. You'll notice my trumpet plants near the shed is in summer mode, which here means losing leaves and just being dormant until Autumn. I water every three days or so and the rocks which are porous, take the moisture down to the roots of the bigger cacti.
Please understand I'm no expert, I just have years of experience trying different things! I recognise your soil type and plant choices as similar to my own and offer these suggestions in hope that you'll get the same success. Make sure each plant has it's own little pocket of good soil and surrounding rocks to protect it. Watch out for snails which also think you are providing an environment for them!
Add a little bit of compost to the base of the plants once a year and just break up the soil which has hardened around the plants a little to let water through for nourishment. When you've done all this your new raised bed should thrive!

[Joel143]

IMG_1632.JPG

I put in a raised bed garden two years ago. I'll attach pics. I found this year when moving things around a bit that the rocks I'd used for weather protection had become root protectors for the cacti. Roots from the taller cacti sought the cooler under-soil of the rock bases rather than go deep into the very poor soil below. The Cycad you have will transfer well if you water it for the first few days. Mine looks a bit knocked about but it was the heat in a glasshouse that did this not the transplanting. You'll notice my trumpet plants near the shed is in summer mode, which here means losing leaves and just being dormant until Autumn. I water every three days or so and the rocks which are porous, take the moisture down to the roots of the bigger cacti.
Please understand I'm no expert, I just have years of experience trying different things! I recognise your soil type and plant choices as similar to my own and offer these suggestions in hope that you'll get the same success. Make sure each plant has it's own little pocket of good soil and surrounding rocks to protect it. Watch out for snails which also think you are providing an environment for them!
Add a little bit of compost to the base of the plants once a year and just break up the soil which has hardened around the plants a little to let water through for nourishment. When you've done all this your new raised bed should thrive!

Cool Potter - Thank you for your input and suggestions. Sounds like a winner to me and I will follow it. Due to the amount of rainfall in my area I will probably make it more porous for faster drainage. Now knowing that even the roots of the larger cacti will spread out rather than down I might lower the height to 18inches rather than 24. You have a great raised bed especially with the larger boulders. I have access to large ones too but they are pricey. I will be using concrete blocks normally used for a retaining wall but plan to place large stones inside the bed similar to yours. I know all will go well just nervous when the rain starts especially when we get rain nonstop for two days straight. If need be I might have to place an overhead roof temporarily. I've been to Hobart before and remember there was quite a bit of rain, if not mist, off and on. Beautiful area though.

[Joel143]

Cool Potter - by the way how did you amend your soil and may I ask whats the depth of your bed?

[Cool Potter]

Firstly, I'm about three hundred km North of Hobart so it's not as wet or cold as that lovely city!

The base soil of the site I choose was almost flat, but the rocks you can see were like icebergs, just peeking out of the surface. We dug these out where we could and put them aside. We live in the bush so soil wasn't a problem. We used a trailer and a spade to dig a site where I thought soil would be good and brought this down to the site. In fact it was from an ancient sand bank and was absolutely dreadful for growing things. We therefore made up about 8 inches of this and then used our precious compost heap to provide a mixture which we could turn into the base 8inches. On top of this I spread a couple of bags of potting mix. Into this still flat surface I placed the biggest of the rocks, adding more from the land around us. Most of them we've dug out of the surrounding ground which is now lawn. Then I put in small areas which were held in by the circles of rock, and which contained ordinary clay soil (red in nature) with the base, a sandy silt and compost. These little pockets I planted with the largest plants first so I could get a feeling of spatial correctness as the other pockets were built. It reguires a lot of 'checking' as you go because as you build higher and higher pockets, the rain and watering tend to drag the soil to a lower lever. When this happened I hand packed (with heavy soil and rocks) until it began to settle. Into each pocket I added a little blood and bone, and when I finished planting I used Seasol solution (weak), (it's a proprietary product here made out os seaweed) to settle plant roots. You'll find that even adding the compost each year few weeds grow. The rocks made the soil surface hot I think and they are discouraged, (somewhat). The solid in the higher sections is about a foot higher than the first layer, but each hole varies according to how energetic I've felt or to how important the plant is to me! Overall I'd say it's about 18'' but it sinks and has to be replenished as things grow!

Hope this helps!

Good luck. Try advertising in your local paper for rocks, sometimes people are just aching to get rid of them!

[Joel143]

Thanks for the info. Helps a lot.

[CactusSquirrel]

I am in southwest louisiana and in the process of starting a small raised bed for a few cacti. How is yours doing? And what did you use to make the cactus soil part? Did you put drainage rocks beneath the soil? I was baseing mine on a design for an alpine rock garden but would love to know what actually worked for you. Our rainy winters is what I am worried about and am trying to choose the cacti and succulents carefully. I'm in a zone 8b/9a area. I am also new to keeping cacti in general.

[Joel143]

I am in southwest louisiana and in the process of starting a small raised bed for a few cacti. How is yours doing? And what did you use to make the cactus soil part? Did you put drainage rocks beneath the soil? I was baseing mine on a design for an alpine rock garden but would love to know what actually worked for you. Our rainy winters is what I am worried about and am trying to choose the cacti and succulents carefully. I'm in a zone 8b/9a area. I am also new to keeping cacti in general.

For my raised bed, which I haven't even gotten half way built yet, is still underway. My cactus soil part I basically used oil absorbent and sandy loam making up the bulk of it. I mixed in alittle potting mix as well but mostly oil absorbent which gives it a fast draining mixture. This is needed as you know from our annual rainfall. My raised bed is in the process of being 18 inches. I figured this is a good depth. My local soil is somewhat fast draining due to it being higher ground but extra drainage is naturally welcomed. Like you I am kinda worried come this winter which will be the first winter I will have plants inground. Right now everything is in pots and have survived winters with no ill affects. I have planned to use a temporary roof that I will build come winter just to give it that extra protection if needed.

[CactusSquirrel]

What is oil absorbent? And where do you get it from? I have been washing pidgeon grit for my potting mixes which is ok for potting things up as I go but not practical for beds. I am also going to make some small boxes for some large opuntias that I have rooting. Do you have a list somewhere of the cactuses you have, I'm curious to what cacti you have doing well overwintering here in pots. I am thinking of using Pooyie bed builder compost or bag topsoil as organic matter but just need to get the gritty stuff.

[Joel143]

I get the oil absorbent from Walmart along with the sandy loam.

[hoteidoc]

Cactus Squirrel - "Oil absorbent": diatomaceous earth, Fuller's earth, NAPA 8822, Turface. Turface I get @ local lumberyard. Also you could use pumice if available. There's a horse stall product -- forget the name -- but if you're around horse country, farm supplies might carry. Also check poultry grits -- they tend to be pretty cheap in big bags.

[mg2007]

Hoteidoc, the horse stall product you are thinking of is provbably "Drystall".

Tsk, and you a vet!!