Pros and cons of lava rock
 

I've been reading a lot about using lava rock for vanda's but I didn't find any thing about them here or maybe I just missed it when reading the threads on potting and repotting, could I use with other orchids too, I'm trying to learn as much as I can about growing and care of my orchids.

Yes it can be used for many orchids,I buy mine at a big box store,a medium sized bag is quite inexpensive. With some orchids you can use it right out of the bag, with others you can break up with a hammer. I have some Cats.in it some Dens. and others. It does hold quite a bit of moisture,but it can also be used for some that like to be drier, it is really quite versatile! A lot depends on your growing conditions like any other medium. It is like everything else,you kind of have to go by trial and error. The hardest part is breaking it up to get the right sized pieces! Get a big hammer..lol...Jean

I use it with my Phals to take up an extra space in a pot and to add some weight to some pots that tend to tip over.
My only difficulty with lava rock is sticking the skewer inside the pot, so I have to rely more on watching glass fogging and moisture droplets. And yes, finding the right size! :blushing:

Agree with the previous post - depends on what you're trying to achieve.

I use lava rock a lot especially in the bottoms of pots to help stabilize them and because here at the beach it is always around 50-60% humidity and media doesn't dry as quickly as I would like. A lot depends on how you grow your rochids. If you grow with just lava you can usually water to your hearts content. It dries fairly quickly. The nice thing about it is that it holds moisture yet doesn't get waterlogged. Here are a couple pics. If used with bark and moss it is the best of worlds. Oh yeah. The phal lived and is doing great. Flowered twice and still in lava.

Does lava rock leach out anything objectionable? I've seen red and grey varieties, is there a difference in their suitability for orchids?

I've been rinsing and a lot of "dust" comes off the rocks. Shoudl I be concerned? I'm new to lava rock, but am planning to use it more as a couple orchids that I bought in rock are thriving in my conditions and I plan to use it in some baskets since it doesn't break down.

I haven't used lava rock by itself for vandas, but I do mix it with other mediums. I use lava rock for semi hydroponic culture and it works beautifully. I'm sure that it would work well alone in vanda baskets but mixing it with coconut chips or moss allows you a few days before you have to water and the pot isn't as heavy.

I use lava rock for most of my orchids, including my vandas and aerides. I use plastic vanda baskets. Provides humidity to the roots and leaves above. I have to water daily when it is really cold but I haven't really had problems. Because you can use it forever, it needs to be flushed well once a month. In the summer, the rains do a great job.

I'm now thinking I might try lava rock because I need to buy more mix for my new orchids and would love to see how they grow in it, as soon as summer gets here they all can go out under the patio where they get lots of light and watered by the rain

It is cheap and it lasts a long time. Just be sure to wash it well.

I will have to take a trip to get it, most of the garden centers around me don't have it in stock, but if it last a long time its worth a trip and who know I might find a orchid or 2 LOL

If you are washing great quantities at once, don't do it in a sink (can clog the sink). I wash it outside or in a bucket, then use the water on my other plants.

I grow nearly everything potted in the red lava rock. The exceptions are my ludisia, bulbo, mounted orchids, and vanilla.

It wouldn't be the first time I clog up the sink from working with plants but I will do it out side just to be safe

I love lava rock, I started last year potting all my catts in it and they grow well, only problem would be watering because during summer you might have to water everyday, OR you can mix with moss which is what I did for the ones that like more moisture.
now I'm trying it on vandas because it didn't matter how much I water didn't look like it was enough, so will see how these do :)
but you can't beat the price, one bag goes a long way

there are different types of lava rock so check to see if it is the type you want to use. if it will fit your bill. the lava rock i usde comes from the eadstern sierra nevada mts in california and i collect it myself. it is full of holes so wicks water up and releases it slowly. some lava rock is just red or grey basalt with few holes so you might as well use plain ol granite. and there is a lot in between. i like what i get. buyer beware.

I will have to look and see what is around, I'll be going out this week end to find some

I just bought some that is used for landscaping. They sell it at our Canadian Tire store to use as mulch. It's good stuff.

I picked some up at a landscaping supply yard. It was in a pile, frozen solid! The worker at the yard had to use a hammer to chip out big icy chunks and put them in a bag for me. Then I put the bag on the bare concrete floor in my basement, on the floor drain, and it thawed overnight. The joys of Canadian winters (Vancouver Island notwithstanding ;)).

So I put a few rocks in a wire basket, and the wire basket in a laundry bin, in the bathtub. Poured tap water to cover the tops of the rocks. The water in the laundry basket turned deep red - no kidding there's a lot of dust on these! We dumped a few laundry basket loads in the back yard (have to be careful not to dump the water onto patio stones, or they will remain red for a long time!) before the water ran reasonably clear. I'm still getting a bit of red sediment every time I shake the basket.

I'm a little concerned about this lava rock, since the same landscaping supply yard sells a lot of road salt this time of year, so there could be some cross-contamination. I hope the soaking got rid of any salt that might have been there.

I'm almost ready to use the rock - I just made a cedar basket for my currently naked vanda, so we'll see how it goes.

The basket looks great! I think that if you have washed the lava rock well that it will be fine. Good luck!

I've found a lot of red dust washes off too. I've been using a big colander and running water through to get the dust off. I may try soaking next time as well just in case.

Nice basket!

I soaked mine overnight, drained, rinsed and repeated a few times. There is still a little dust in the s/h containers, but it does no harm.

I got a bag of lava rock today, the price wasn't that bad just a little over what I pay for orchid mix, I washed and made sure there was no dust in the last rinse the re potted a catt. in it I do like the looks of it, I'm thinking that I'll repot my others in it when they need to be repotted.
Thanks for all the great help, I now feel better about how I grow my orchids.

You can incorporate moss into a lava rock mix if you need more moisture.

this is really Rays topic. Hes an eye opener and considers all things. Your vanda will grow in nothing but a wooden basket. Like most orchids they will grow in next to nothing. Is why we put stuff like mix rocks moss etc etc on our orchids is bec we dont have a tropical climate thats moist wet or humid enough to sustain the aerial roots needs for moisture. Vandas be very water heavy plants. Planting the vandas in lava rock isnt going to make a bit of difference if you arent watering them enough. You can water them enough without the rocks is my point. Lava rock collects a lot of chlorides and salts in them tiny cracks. The tiny cracks will also collect a lot of water and restrict air movement across the roots. Think about it.

I used lava rock (cinders) for decades in growing bonsai and never had an issue with it collecting chlorides or salts. Because it absorbs water and then releases it slowly the water trapped in the pores of the rock is always readily leached out by the next watering. And because the rock has sharp angles and corners it never restricits the movement of air. If you put too much small moss in it that may clog the air spaces. But everything I have planted in lava is doing well. True the media is not really needed because most orchids can grow in no media at all but it does help to stabilize the plant and another nice thing about lava rock is that the roots don't seem to cling as tenaciously to it. I think that is partly due to the small void spaces in the rock itself. When I go to repot an orchid from lava rock, the roots are very healthy and the rock usually falls off the roots easily. But lava rock is heavy so when you do repot, you have to be careful when pulling the plant out of the pot. I just put the pot on it's side and gently pull the plant out. The rock usually falls away from the plant easily. What remains I leave. Rock is not for everyone. Give it a try in one plant and see if it is good for you. One other thing is that because the water adheres to the tiny cracks, the fertilizer is available longer just like in nature. But with the next watering it is leached away. Wednesday evening our orchid club had a great speaker from Gold Country Orchids here in California. He suggested that coral might be a good material for orchids to be grown in because a lot of orchids need calcium to grow well. Just a thought. Sorry I didn't get more info. I was busy trying to pick up on a new gal that just joined the club;->

This vanda WAS growing in nothing in my home for over 3 months, and it was not doing well. It has dropped 5 lower leaves since I got it. The humidity in my house is 60-70%, which is pretty good for a house in Canada in winter. But not enough. That's why it is now in a basket with lava rock, charcoal, some coconut husk chips and a bit of sphagnum in the slats, keeping the charcoal from falling out. I hope it does well, otherwise the next step is a vase.

I agree with you, James.
The idea of coral sounds interesting. I was wondering about the possibility of using it. I had a box of bird gravel on hand and since it contains calcium, I added it to my cymbidium mix. They grew well, but they might have anyway.

I think for the calcium to be readily available the pH of the water has to be around 4.5 to 5.5. If Ray is listening, please chime in as this is your expertise. But it may slowly leach out with each watering. I wasn't listening very well. And no I didn't get a date. (dang it. She is cute)

One thing I learned awhile back is that vandas need maximum light levels. They need all the light they can get. Here in SoCal most grow them outside in full sun. If not enough light they lose leaves and slowly die back. I think light is more important than water. I would think in the northern areas the winter would be really hard on them but the summers they would really take off due to the greater length of daylight. Anyone know if this is true?

A few years ago I decided to try Vandas after reading the 'Vandas in Vases' article. Initially I had good results with that technique but after a couple of years it was apparent that they were on the decline. Not much root growth and shriveling leaves.


The next summer I tried them bareroot in clay pots and stuck them next to the misters. That got some response, root growth and leaves looked better.
Unfortunately that works only in summer when they are in my greenhouse. Inside my house during winter is dryer plus I don't water them as often as I should.

Last spring I made cedar baskets (not as professional looking as Al's ;)) and filled them with large lava rock - 2 inch average.


The plants are happily filling the voids and basket openings with roots. More importantly this growth has continued throughout the winter indoors. I soak them every 3 days or so. The cedar stays damp and the rocks hold moisture but there is lots of air circulation.


I don't know what the long term outcome will be but this is the best solution I've found for the Vanda situation.




Maureen

That sounds like a good idea. I tried growing bare root in the house and it just wasn't practical. They would dry out too quickly or if I watered too often when the humidity was high the roots would rot. Our humidity is high during the winter. I found what worked for me was baskets with sphag and charcoal, but lava rock is less messy and doesn't break down. Maybe I'll try that for the next one. I'm used to being able to feel whether they need water, though.

I've tried bare root for vandas in my greenhouse and they nearly died. Then I tried hydroton. The salt build up nearly killed all the roots. So I switched to lava rock and all the vandas have bounced back and the leaves all look great. I find that as long as I water the vandas in the morning no later than 10 am they all dry out by nightfall or shortly after. I doubt ill use anything else for vandas in the future.

Eventually you may have trouble with the lava rock becoming saturated with salts. Be sure to flush really well with clear water often. I have some plants in s/h in lava rock. they love it but I have to be careful or they show signs of too much salt buildup.

That's what I've noticed. But the salt build up isn't as bad as it is with hydroton. A good flush is enough for the lava rock but the hydroton just builds up even with a few flushes.

It does work well for s/h too, and it is so much cheaper than Hydroton. It is also easier to get, since it is used a lot in landscaping.

in regards to vandas in lava rocks; I have a pachara delight potted in lava rocks for about 2 years+ and it has been blooming 3 to 4 times a year as schedule. I water it every 2 or 3 days or whenever it looks like its dry. It grows outside in the floor of my shade house, takes sun from sunrise to about mid day because my shade house has a roof, it only comes in to the house when in bloom
I do have well water so I don't have to worry about chemicals in the water.
I wish I could post pictures in here but after trying several times in the past I gave up, dont want to go through the hassle

I have been thinking about trying vandas in lava rocks but I have them in baskets and wondered if it might be too heavy. I like lava rock because it doesn't break down and I'm pretty sure that bugs don't like it as much as other mediums.

the pachara delight I have in lava rock its with basket and all. The roots were wrapping around the wood basket but I couldn't keep up with the watering schedule and I wanted to bring the plant in to enjoy its long lasting blooms. I put big lava rocks on the bottom of the pot (biggest on the bag sold at home depot or lowes) then the wood basket and a few more lava rocks around to stabilize it. It has grown a lot ! I can also see new roots growing inside the pot.
It is a big pot. I dont know the exact size but I think its a gallon or close to it. Also, it is a terracotta pot.
Hope this helps.
Overall I'm really happy with lava rocks, I have used it for everything. Phals, Maxillarias, catts, dens and oncidiums. They all grow big roots and strong blooms.

I think that as long as you aren't hanging the basket, lava rock would be excellent. Especially in winter when the roots that are outside the basket always seem to be too dry, even with daily misting,