I am looking for some help with three San Pedro cacti I recieved as a gift a couple weeks back. They were shipped quite a distance but the cuttings looked good when they got to me. Now they have developed large black spots that seem to be disintegrating parts of the cacti. They also have smaller black dots over some of the surface. I'm hoping someone here can give me some advice on how to save these plants! I have been watering once a week and try to get them as much direct sunlight as possible but being renter it is hard to get them more sunlight. With cold weather around the corner I'm trying to get them as healthy as possible before they need to be pulled inside. Any tips would be appriciated as these are my first cacti.
I'm not trying to stress you out any further, but that soil mix looks like it has way too much organic material. Most good mixes have at least half inorganic lightweight substrate, such as pumice or perlite.
LawyerNinja wrote: ↑Tue Sep 22, 2020 3:38 pm
Damage from staying in a box for too long. If you keep them in the sun give them some time before watering they should be fine.
You may need to do a little surgery if the larger black spots progress.
Humidity and movement in the box were not kind.
Do they have roots?
They do not have roots but I have been giving them one cup of water a week since potting them. Should I stop giving them water?
tumamoc wrote: ↑Tue Sep 22, 2020 5:00 pm
I'm not trying to stress you out any further, but that soil mix looks like it has way too much organic material. Most good mixes have at least half inorganic lightweight substrate, such as pumice or perlite.
No worries about the stress, any information on how to care for them is appriciated.
I found a site that has information on mixing your own soil but is there a soil you could recommend for purchase?
I don't think you need to throw out the soil that your cactus is planted in, but you can amend it with some porous, well-draining mineral substrate, and you don't have to break the bank to do it. To be honest, I wouldn't trust anything sold as cactus potting soil at a big box hardware store (e.g., Lowe's and Home Depot). Do you live in an area that has nurseries that specialize in cactus and succulents? They often sell small and medium size bags of their cactus potting blend. If you can't find a good mix locally, you can should be able to find a bag of perlite or calcined clay bits (e.g., Turface MVP). Not all places have pumice, but that is one of the most common ingredients. Hell, if it's just one plant to pot up, you can find some quarter-inch or smaller gravels and coarse sand at home to help with the drainage. Except for pumice and scoria, rocks aren't usually used in mixes because they add a lot of weight. But do what you gotta do. If you do get serious about growing cacti, you'll definitely want to make your own blend or buy in volume so the price of soil per pot is minimal. Good luck.
tumamoc wrote: ↑Wed Sep 23, 2020 7:42 pm
I don't think you need to throw out the soil that your cactus is planted in, but you can amend it with some porous, well-draining mineral substrate, and you don't have to break the bank to do it. To be honest, I wouldn't trust anything sold as cactus potting soil at a big box hardware store (e.g., Lowe's and Home Depot). Do you live in an area that has nurseries that specialize in cactus and succulents? They often sell small and medium size bags of their cactus potting blend. If you can't find a good mix locally, you can should be able to find a bag of perlite or calcined clay bits (e.g., Turface MVP). Not all places have pumice, but that is one of the most common ingredients. Hell, if it's just one plant to pot up, you can find some quarter-inch or smaller gravels and coarse sand at home to help with the drainage. Except for pumice and scoria, rocks aren't usually used in mixes because they add a lot of weight. But do what you gotta do. If you do get serious about growing cacti, you'll definitely want to make your own blend or buy in volume so the price of soil per pot is minimal. Good luck.
I found some perlite that should be enough for all the plants for $5. I'll try mixing that in and see if it helps.
Well sounds like you are well on your way. The only downside to perlite is that it floats away when water gets to it, so you'll probably need some kind of top dressing to keep it all contained. If you're budget conscious like me, you just go out to your yard and sift through some gravels to fill the pot. It's really easy for me. I live in the Southwest where surface gravels abound and peoples' yards consist of landscaped rocks instead of grass .
THanks for all the info everyone! THey seem to be doing a lot better. The damaged areas have stopped growing and the spines on the cacti have been growing back. When I repotted them with the perlite mix they don't seem to be growing any roots as of yet. It has become to cold to keep them outside any longer so I have brought them inside. I have a few questions because I've been getting mixed information online. Are there any winter/indoor care tips that I should be looking at? Should I be watering before the plants have developed roots?
Laharan wrote: ↑Tue Oct 20, 2020 11:06 pmIt has become to cold to keep them outside any longer so I have brought them inside. I have a few questions because I've been getting mixed information online. Are there any winter/indoor care tips that I should be looking at? Should I be watering before the plants have developed roots?
Without roots, cacti won't be able to take up water. Desert cacti go dormant in fall and winter, so look for new roots stubs sometime in spring. Once your San Pedros start grabbing into their pots, they'll be ready for watering.
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