I have grown a lot of different plants from seed but there is a challenge I encounter with many cactus and succulent seeds. At around the size of a dry pea they stop growing. Eventually some bounce back and start growing again but some never do and eventually die. (currently I have some frailea I started in 2021 the largest is about the size of a dry pea the rest about the size of peppercorn.) So I'm looking for any advice to improve seedling growth. I will provide as much info about my current growing conditions as I can below.
I live in Chicago and so I grow my seeds indoor under grow lights until it is safe to move them outdoors the next summer. I started a variety of different seeds over summer all have stopped growing. I started them in a humidity tray in washed builders sand. (In the past I used coconut coir but stopped do to mold and plants damping off.) I left them in the humidity trays until haworthiopsis, psudolithos, &, Whitesloanea crassa seedlings started dying about 5 months later. After that I took them out and cut back on watering to twice a week. PH of water is about 6.3 Temperature average around 72 ° farenhight. Fertilizer I started with was Bonide Liquid Cactus Plant Food, but I switched to Liqui-Dirt a few weeks ago. (I haven't noticed any change)
Light - Cresmar P1200 LED Grow Light. The lighting varies depending on their position:
120 µmol/m²/s - Psudolithos cubiformis, pseudolithos migiurtinus , Whitesloanea crassa, & Pilosocereus leucocephalus
The Psudolithos & Pilosocereus appear a heathy green color. The Whitesloanea looks kind of yellow/brown looking, not sure if that's normal for it.
70µmol/m²/s - aloe hybrids
They look sun stressed, but I am not worried about these since I grow a lot of aloe and they always start growing again in Summer.
40 µmol/m²/s - aloe hybrids, & haworthiopsis
These aloe hybrids look heathier.
