It's time to vote on our 2017 photo contest! Vote for your favorite photos of the year here!

Vermiculite - did I make a mistake?

I have some alpine plants which I recently transferred to a container. I read I should put them in soil which is a mix of John Innes no. 2 and horticultural grit. The grit bags in the store were too large to lift so I bought vermiculite instead as it said it improves drainage and can replace grit. I used a 50/50 mix of the compost and the vermiculite, as it said to do on the bag. Now I've been reading that vermiculite retains water and that also 50/50 mix seems extremely high. I live in an area where it rains quite frequently. Have I made a huge mistake?

Ayrshire Scotland, United Kingdom

The quick answer is YES !!!!, the Vermiculite does help with water retention, and most Alpines don't require too much water as they gather their moisture (in their natural habitat) from dew, moisture run off from rocks / stones and nature allows them to survive with very little water, in-fact, too much damp or wet soil will normally rot the plants at the neck / roots.

IF you possibly can, look for a smaller bag of sharp small grit, remove the plants from the soil in pot's and mix in the grit, this will allow air, loosen / open up the soil and allow free drainage when you do water.
Another thing Apoda, don't let the pots sit in excess water in saucers as this will make the soil act like a sponge and pull the water from the saucer back into the pot.
IF you do have water sitting in saucer, leave for maybe half hour, lift out the pot, throw away the water and set the plant back in place. For Alpine plants, I like to water the plants from the bottom as some don't like moisture on leaves.
Watering from bottom is easy, fill the saucer with water, leave for half hour, pour away water, allow the extra water to drain away, by this time the soil should have pulled the water up into the pot reaching the roots.
To check if water is required, stick finger into pot soil and if dry give water, if damp or wet, don't water. Some garden DIY stores sell small bags of grit and you may find it better BUT don't use builders grit/ sand, use only Horticutural stuff as the builders materials can have salts or other stuff added and this is NOT good for plants. meantime try NOT add too much water to plants until sorted.

Hope all goes well for you and your plants.
Kindest Regards.

Thank you for your very helpful answer.

I've seen smaller bags of gritty looking stuff in aquarium shops. Would that be ok to use?

At the moment my containers are standing on grass with no saucers underneath. Should I get saucers?

I also have a coleus and a geranium in the vermiculite mix soil. Do they need to be put in a different soil too?

Ayrshire Scotland, United Kingdom

The grit / gravel you would be better to use is stones just a bit smaller than your small finger nail, I'm talking about the pink area of nail, NOT the whole female finger nail that is about half inch longer after the fleshy pink area.

I would think the gravel stuff for fish is way too fine and would get washed out from the soil / pot, I would remove the plants from the grass as this grassy area will attract all sorts of crawling, flying or other insects that will want to bury under the pot for daytime shelter away from predators and come eat your plants at night, things like slugs, snails, grubs that at this time of year get laid in the grass by the parents and live on grass or plant roots.
Be best to place them in a tray put onto a table, stone or other flat surface, this will help control watering, will let you see IF any pests like greenfly or other aphids are sucking the plants, And also, the grass will hold onto moisture and for now, you should aim to try be more in control of the water the plants get.
Coleus and Geraniums need a bit more water from below, don't put water on the leaves as both have fine hairs and water droplets laying on the leaves because the fine hairs help to keep the droplets in place aint too good for these plants, again, try water those 2 plants like the others, from the bottom as mentioned above.
Hope this helps you out.
Best Regards.

Baja California, Mexico(Zone 11)

Please excuse my intrusion. I have used rock from aquarium shops. Lava rock (aka cinder rock) is what I would go for, given the choice. The bubbly type. I like about 1/2 cm (1/5 inch) size. Depending on the source you should consider washing the rock a couple of times with water before use, and/or screening the rock (with a kitchen sieve for example) to remove the fines.

Ayrshire Scotland, United Kingdom

Hi Baja, never apologise for joining in with help on a thread, were all here to learn things and to be honest, I've never heard of the Lava Rock or anyone who uses it in the garden context so please, no one owns the threads or forums as far as I know.
Please make sure IF you have help or hint's tips to offer, let's hear them. the one good thing about the site is, Most people are very friendly on the site and can also give fun and light hearted replies too.
Best Regards.

Hi Baja, thank you for your input. The more information I can get, the better!

My plants are now on a table. When I picked them up a lot of water came out of the bottom of the pots so I'm guessing the grass was preventing them from draining. I didn't know that could happen.

I gave up on trying to get the grit and got some perlite instead. Is it ok to use perlite?

Baja California, Mexico(Zone 11)

Yes. Wear a mask when you handle the perlite as it tends to liberate a lot of nasty dust. Also consider putting some gravel on top when you're done as the perlite tends to float to the top.

To avoid standing water in pots I always lift them above the floor/ground, just a little bit, so that gravity solves the problem. You can put down an inch of gravel below the pots and that will do the trick too.

Post a Reply to this Thread

Please or sign up to post.