hey guys, i'm a virgin with growing cacti from seed. i was wanting to start with trichocereus(columnar
. so i'm guna throw heaps of questions at you, your advice will be deeply appreciated. here goes.
.best soil and at what depth?
.how often should the soil be watered
.any foods in the soil?
.should it be in the dark till they sprout?
.what heat should the heat mat be in the day and for how many hours?
what heat at night and how many hours?
At what point do i add growth light?
.how far appart should the seeds be spread?
.do you bury the seeds or just put ontop of the soil?
.how long does it take for them to sprout?
should i microwave the soil first to sterilise?
. how humid should the grow box be?

Sounds like you need to do some more research. Read this which will answer most, if not all of your questions.

Closet Cactus Care by M.S. SMITH

nice one.
cheers

one thing i can say is definitely microwave your soil. someone told me that it was a waste of time just before i sewed my seeds, now i have gnats and algea.

Yes, microwaving soil is essential. sterilization of the soil media is of upmost importance.
Get some fungicide. Try to find one specific for Phytophtora and Phthium spp., the fungi that cause damping off infections, a common problem with seedlings. I have been using Fongarid, a systemic, will good results, get it from Bunnings.
sow the seeds on the surface of the soil with a light covering.
Try to keep the propagator at around 27C for germinating seeds. put a termometer in there. a little above or below this doesn't hurt, although warmer is perhaps better than cooler for most species. Trichocereus are often very vigorous from seed and you should get very good germination with fresh seed. sow fairly thicky so they support each other when growing, but they will probably need thinning out quickly as they are fast growing cacti.
keep the seedlings under an airtight plastic cover (eg glad wrap) to prevent drying out during the intial stages of development.(this also prevent entry of sciarid fly/fungus gnats). or use the baggie method. At this time of year in melboune you cannot live without a heat mat for germinating. I keep the heat mat on 24/7 now in winter, and have the lights on a timer. It is recommended for germination and general seedling health to have some temperature fluculations from day and night, day being warmer and night being cooler, but not cold. This is provided naturally as the lights produce additional heat during the day and its up to the heat mat at night. You can keep the lights on for up to 16 hours daily. seedlings enjoy these long hour conditions.this ensures they continue to grow all winter.

Instead of microwaving the soil you can put the pots with soil in a flat container and let them soak up boiling water. I do this in kitty litter trays and let the water come to nearly to top of the pots. Let the water cool take out pots and let them drain well and sow away.

Saves the smell in the microwave

I wipe out the microwave out with vanilla essence on a damp cloth then toss the cloth into the wash. every time I pot up now I use microwaved soil.

I couldnt be bothered microwaving the soil this time round. Too many pots to fill and im lazy. All goin great so far, trichos are booming. In actual fact, the tricho seeds i threw into an old take away container with dirt from the closest pot plant are doin the best this season lol. Just wish i could remember which cross it was :S

I have recently learnt that a lot of people overseas re-use the soil from their seedlings.

I have kept the soil from last spring and will put it in a bed come spring to see what may grow. I have had seeds that didn't germinate one year come up the next.