Alrighty so this will be my first post on here- I've been growing cacti for a handful of years now, and recently I've been wanting to branch out into growing cacti from seed, as I have the time/patience, and it would be a LOT easier on my bank- The only problem is there's a LOT of drastically varied information out there, and I have enough basic cacti knowledge to know that something's not quite right with most of the readily-accessible information I'm coming across, but not enough about growing cacti from seed to know just how incorrect it is, or isn't.

All of this to say- Are there any experienced growers who can answer some questions for me, and potentially help any other people who've been wondering the same thing?

What soil mix do you recommend? I keep seeing people suggesting I use cocopeat, or normal potting mix, which doesn't seem right- But I'm a snob about cactus mix, I don't let those things anywhere near my collection, as I use pretty much entirely grit and the only organic material I use is pine bark fines because I live in a swamp with crazy high humidity so if I use anything else I get rot. Are there any better mixes?

Fungus control is another issue I'm concerned about- I get mold in my open-aired leaf propagation trays if I so much as mist them every other day, and I've had similar results with closed propagation containers to encourage root growth, and most of what I see is plant seeds in wet soil and bag them up to let them germinate/grow enclosed for a while, how do you avoid mold issues? I've heard that a lot of fungicides can seriously stunt germination/seedling growth, but the only safe fungicide recommendations I've found for seedlings have been from out of country and when I looked for the kind they used, I couldn't find any available to me.

Growing from seed is an entirely new world for me and I'm so very lost- I would greatly appreciate any information provided! I'll probably have a dozen more questions once these have been answered!

Sterilize your soil before you plant? I have seen people bake their soil like bread inside an oven on an extra sheet pan, with tin foil covering the top. I am pretty sure grilling tin foil soil packets should also work. Maybe try searching up soil sterilization?

I use a mix of 50% pumice, 50% organic and do not suffer from problems with microorganisms. With bigger seeds, the baby plants are independent sooner, so sterilization is not much of an issue. With small seeds that need to be covered for a long time, I cook the soil in a microwave before use. Method below.

Use new pots or sterilize old ones with bleach before use if you want to reuse them. Fill the pot (typically 4 inch size) with soil. Water to completion with clean (purified, bottled) water, allow to drain completely. Place pot on a clean saucer, cover with a clean saucer (I like to reuse lids from plastic containers). Microwave on low (I use 15% power) until well past the point where the pot becomes too hot to touch. Usually there's a sweet earthy smell in the air by the end. Let cool in the microwave ideally or remove and allow to cool to room temp with the lid on. The lid should stay on until you sow. Right before sowing, water again to saturation (some/most of the original water will have boiled off) and allow the excess water to drain out. Sow efficiently and cover with clear plastic wrap (I use a rubber band around the mouth of the pot to hold it on) right away. Leave the plastic wrap on top until the baby seedlings are roughly the size of a small cooked pea (a few mm), and only then remove it. This may take weeks or months depending on the seed size and rate of growth. Strong light is important during this period. I have found no location better than right in front of a sunny southerly facing window.

If at any point you think your baby seedlings may need water, you can bottom water them with purified (bottled) water. Instructions available upon request. Unless they're sitting for months, they probably will be fine until you lift the lid.

Baja_Costero said:I use a mix of 50% pumice, 50% organic and do not suffer from problems with microorganisms. With bigger seeds, the baby plants are independent sooner, so sterilization is not much of an issue. With small seeds that need to be covered for a long time, I cook the soil in a microwave before use. Method below.

Use new pots or sterilize old ones with bleach before use if you want to reuse them. Fill the pot (typically 4 inch size) with soil. Water to completion with clean (purified, bottled) water, allow to drain completely. Place pot on a clean saucer, cover with a clean saucer (I like to reuse lids from plastic containers). Microwave on low (I use 15% power) until well past the point where the pot becomes too hot to touch. Usually there's a sweet earthy smell in the air by the end. Let cool in the microwave ideally or remove and allow to cool to room temp with the lid on. The lid should stay on until you sow. Right before sowing, water again to saturation (some/most of the original water will have boiled off) and allow the excess water to drain out. Sow efficiently and cover with clear plastic wrap (I use a rubber band around the mouth of the pot to hold it on) right away. Leave the plastic wrap on top until the baby seedlings are roughly the size of a small cooked pea (a few mm), and only then remove it. This may take weeks or months depending on the seed size and rate of growth. Strong light is important during this period. I have found no location better than right in front of a sunny southerly facing window.

If at any point you think your baby seedlings may need water, you can bottom water them with purified (bottled) water. Instructions available upon request. Unless they're sitting for months, they probably will be fine until you lift the lid.

Need to make this post another sticky topic for users. IMO

Baja_Costero said:I use a mix of 50% pumice, 50% organic and do not suffer from problems with microorganisms. With bigger seeds, the baby plants are independent sooner, so sterilization is not much of an issue. With small seeds that need to be covered for a long time, I cook the soil in a microwave before use. Method below.

Use new pots or sterilize old ones with bleach before use if you want to reuse them. Fill the pot (typically 4 inch size) with soil. Water to completion with clean (purified, bottled) water, allow to drain completely. Place pot on a clean saucer, cover with a clean saucer (I like to reuse lids from plastic containers). Microwave on low (I use 15% power) until well past the point where the pot becomes too hot to touch. Usually there's a sweet earthy smell in the air by the end. Let cool in the microwave ideally or remove and allow to cool to room temp with the lid on. The lid should stay on until you sow. Right before sowing, water again to saturation (some/most of the original water will have boiled off) and allow the excess water to drain out. Sow efficiently and cover with clear plastic wrap (I use a rubber band around the mouth of the pot to hold it on) right away. Leave the plastic wrap on top until the baby seedlings are roughly the size of a small cooked pea (a few mm), and only then remove it. This may take weeks or months depending on the seed size and rate of growth. Strong light is important during this period. I have found no location better than right in front of a sunny southerly facing window.

If at any point you think your baby seedlings may need water, you can bottom water them with purified (bottled) water. Instructions available upon request. Unless they're sitting for months, they probably will be fine until you lift the lid.

Thank you so much for getting back to me! Okay so- New questions as promised, what organics do you typically prefer? I've heard several different opinions, typically coco choir, peat, and one that caught my interest was rice husks, do you prefer one of those over the others, or have any pros/cons with them?

And temperature/time of year, what is the best time of year to start growing? I don't have good windows/space in my house to start em on a window in-home, I overwinter my plants in an airstream mobile home on my property with a grow light, which protects them from frost but also isnt heated either- Would heat mats be necessary to start in winter? Do you have cheap recommendations if so, or would it be best to wait until it's warmer to start them?

Last few questions for this reply- Is it possible to overcook soil?? How long do you typically nuke a 4 inch pot, when on the 15% setting? (I know I'll likely need to adjust but having a general idea of how long I should pop it in should give me an idea of what to work off of.) Also, for a 4 inch pot how far should it be filled with soil/how far from the lip should it come up to?

My mix for starting seeds (and growing succulents down the road) is 25% compost (locally sourced, unlabeled bags), 25% cocofiber (coir), 50% pumice. I use a smaller size of pumice for seedlings compared to adult plants. The compost breaks down and after a year or two sort of turns to dust, thus the cocofiber, which is longer lasting. After a few years the soil is probably closer to 1/3 cocofiber, 2/3 pumice. I think peat should perform roughly like cocofiber, maybe be a bit slower to re-wet, but same concept.

I start seeds whenever I feel like it (any time of year). You just need to be sure that there will be ample light and moderate temperatures. I typically start them indoors by a window, where the temps are in the 60s during the day in winter and probably don't get below the 50s at night. If you aren't able to provide those temps then you might investigate heat mats, but I have absolutely zero experience with them so I'll let someone else answer about that.

I suppose you can overcook soil. I've never gone over the line. Usually it takes me about 23-25 minutes to cook two 4-inch pots. The finger test is pretty good for telling you when temps are >120-130°F, and I might go another 5-10 minutes after that point. Obviously this is not an exact science. Basically you're steaming the soil using the water it has absorbed. Whatever works the first time willl work after that point. It's not total sterilization, ie. you will get algae growing in there, but I think it helps with fungal stuff (along with good hygiene, of course).

I use pots with azalea proportions, filling the 4 inch size to about 2.5 inches deep, about half in inch from the lip. The soil will shrink down into the pot after you water so you might want to top it off with soil and water again before you're satisfied.

For the purpose of seed starting, I follow a few rules with moisture. Baby seedlings only go in one direction, from total saturation all the time toward a cycle alternating wet and dry. Bigger seeds might go from lid on to lid off within days after germination. I'm talking peppercorn size seeds here. Smaller seeds will do better under saturated conditions for longer (dust-like seeds being extreme in this respect), and they generally require a more gradual stepwise progression as they are being weaned from humidity. That might mean some regular misting after emerging from under cover, ensuring that the soil always has some moisture in it for the weeks right afterwards. At some point I know I can water twice a week and the soil will go mostly dry at the bottom through evaporation alone. Sometimes all the way dry, depending on conditions (which are very mild, usually near room temperature). That's my basic frequency for young seedlings, twice a week in those 4 inch pots, basically until they are big enough to leave the house and go live outside. At which point they get water once a week, from there on out, in the same 4 inch pots.

This is just an example, based on the permissive conditions we enjoy, but it should hopefully give you some idea of the progression you have to go through to get from point A to point B. Part of the challenge is knowing how fast you can go, and ideally knowing which steps you can skip.

By way of an anecdote that breaks all the rules, there's a native succulent from here (Dudleya species) which makes really small, dust-like seeds. I have never actually cooked the soil and sowed the seeds and put a lid on with that plant. My solution has been to park a pot with soil and some top dressing (chunky pumice) right below a dry inflorescence, let wind and gravity work their magic, and water once a week. This pot sits in day-long sun (so much for protecting baby seedlings) and the soil dries out fully every week (so much for gradual weaning off the water). But those conditions are plenty sufficient to drive lots of germination and each year the young 'uns battle it out. The stronger plants that survive will go and get separated once they are roughly fingernail sized. I've gotten dozens of plants out of this arrangement and even though it breaks the rules I described above, that doesn't seem to matter. Then again the species is native to rocky slopes on an island 50 miles northwest of here, so it's pretty much right at home.