Experiences with pumice and red or black lava stone to sow seeds
Experiences with pumice and red or black lava stone to sow seeds
Do you have experiences using pumice, red or black lava stone to sow cactus or succulents seeds?
Re: Experiences with pumice and red or black lava stone to sow seeds
I use very fine red lava (scoria) as a thin top dressing to sow my seeds on. They germinate well because the particles hold a good amount of moisture and seem to encourage root hairs to form. Pumice is also good but I find all the light coloured materials to encourage the growth of algae. Make sure you wash the scoria well before using it. Also, some samples of lava have been shown to be toxic. If in doubt, you can do the radish seed test - put some scoria in a pot and plant some radish seeds. After a week or 2, empty out the pot and check the roots. If they have nice clean, white tips, (use a magnifying glass) the material is fine. If they have brown tips, not so good or downright disastrous.
- greenknight
- Posts: 4853
- Joined: Tue Apr 30, 2013 4:18 am
- Location: SW Washington State zone 8b
Re: Experiences with pumice and red or black lava stone to sow seeds
I use a blend of 3 parts pumice and one part good quality potting soil, pasteurized in a microwave. It does tend to grow algae, but the algae is harmless to the seedlings. Cactus seedlings make strong root growth in this mix.
Spence
Re: Experiences with pumice and red or black lava stone to sow seeds
I use 1/3 sand and 1/3 sandy soil from the desert and 1/3 dry stall pumice for mesembs , same for cactus but maybe less sandy soil for cactus . lava rock I have used with mixed results same with turface. Store bought soil also not very good results.
Where you get the sandy soil is pretty important and how to test if its any good IDK ? trial and error I guess. With cactus seedlings if they mold up and die right away its no good . I don't microwave the soil.
Where you get the sandy soil is pretty important and how to test if its any good IDK ? trial and error I guess. With cactus seedlings if they mold up and die right away its no good . I don't microwave the soil.
- jerrytheplater
- Posts: 1213
- Joined: Mon Mar 22, 2021 7:38 pm
- Location: Bloomingdale, NJ (USDA Zone 6b)
- Contact:
Re: Experiences with pumice and red or black lava stone to sow seeds
I like that radish test. Good idea.MikeInOz wrote: ↑Thu Oct 12, 2023 5:28 am Also, some samples of lava have been shown to be toxic. If in doubt, you can do the radish seed test - put some scoria in a pot and plant some radish seeds. After a week or 2, empty out the pot and check the roots. If they have nice clean, white tips, (use a magnifying glass) the material is fine. If they have brown tips, not so good or downright disastrous.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
Re: Experiences with pumice and red or black lava stone to sow seeds
Yes it's very simple and pretty much fool proof.jerrytheplater wrote: ↑Sat Oct 14, 2023 12:28 amI like that radish test. Good idea.MikeInOz wrote: ↑Thu Oct 12, 2023 5:28 am Also, some samples of lava have been shown to be toxic. If in doubt, you can do the radish seed test - put some scoria in a pot and plant some radish seeds. After a week or 2, empty out the pot and check the roots. If they have nice clean, white tips, (use a magnifying glass) the material is fine. If they have brown tips, not so good or downright disastrous.