One of the bigger problems amateurs find in growing new hybrids is young seedlings sensitiveness. Most cactus seeds are very little ,and very little and delicate green spineless plants come out.

just born thrichocereus

They need water otherwise they easily dry up, they need light but you must avoid direct sun light , they easily rot because of fungi , and they need 25-30°C to grow . I have not a greenhouse ,so in 1996 I tried to grow them outside ,on my balcony,but I was not able to get anything .From next year I begun to use a heated-box in order to grow young seedlings . Dimensions of my heated-box are : 100x50cm,it's lightened 18-24 h. every day by three 30W GroLux Neon Lamps . Lamps are 12-15 cm over the seedlings, and temperature inside is 25-30°C . If you use a heated box you can plant seeds anytime of the year :In autumn I plant seeds produced by my cacti duringummer , so I gain one growth-year.

To avoid fungi development inside the heated-box : 1) I use little pots 2)I use soil without decomposing material 3)Seeds are accurately washed before 4)I add Chinosol to water . Remember always to record the name of parents of your hybrid , writing it on a label.
For example Trichocereus thelegonus x Echinopsis Kermesina means that a Trichocereus thelegonus was crossed with pollen from Echinopsis Kermesina .