Instructions: Sowing cacti
There are a few things to keep in mind when sowing cacti:
Sowing soil : Since cacti need a long time to germinate and/or to reach a sufficient size for pricking out, an unfertilised, nutrient-poor and germ-free substrate is recommended. I recommend a mixture of 70% coconut substrate (e.g. BioBizz Coco-Mix) and 30% 0.5-2.5mm high-grade pumice (e.g. high-grade pumice from Rotec). This substrate mixture is slightly moistened and filled into a heat-resistant container (preserving jar) and sterilized in the microwave for 4 minutes at 800 watts. Sterilizing reduces the chance of fungal or bacterial infections developing during cultivation.
Indoor greenhouse : When choosing a suitable container for sowing, commercially available indoor greenhouses can be used. I use so-called Meal-Prep plastic boxes for my sowing, corresponding to the to-go packaging at Asian restaurants (transparent lid, black bottom).
Location/time : A windowsill facing south and sowing at the beginning of April is suitable as a location for the germination trays.
Temperature : It is essential to ensure that the germination bowls are at a good temperature (20-30°C), appropriate heating mats can be used for this.
Artificial light : I had the best experience with sowing under full-spectrum LED plant lamps (Viparspectra XS1000/2000 & P600/P1000), sowing can be planned well. When sowing under artificial light, I recommend sowing in December-January, here the seedlings can, with proper care, be pricked out in April-May and migrate to the greenhouse.
Implementation : First, the clean seed trays are filled with 4-5 cm of substrate and the substrate is lightly pressed on. It is important to ensure that the substrate is evenly distributed and that no bumps have formed. The seeds are placed on the pressed substrate and lightly pressed with a spoon. A distance must be maintained between the seeds to facilitate later transplanting. The substrate is then moistened with a sprayer, it should only be damp, but not really wet. It makes sense to look at the condition of the substrate after a day and, if necessary, to moisten it again. With good preparation (sterile substrate), the lid can remain tightly closed during the entire cultivation and ventilation can be dispensed with. After a week, depending on the variety and conditions, the first seeds should germinate. The seedlings should only be pricked out when the roots have no more space or reach the bottom of the dish (beet roots).
Watering the seedlings : Since moisture will also escape from the seed trays over time, they must be moistened from time to time. Soft water is suitable for this. An addition of field horsetail can inhibit the formation of fungi and bacteria and lead to healthy growth of the seedlings.
Fertilizing : It is absolutely necessary not to fertilize the seedlings in the germination trays, as this can lead to contamination with bacteria and fungi. I recommend the first light fertilization a month after pricking out if you continue to use nutrient-poor substrate.
These sowing instructions are suitable for almost all cacti, they are based on personal experience when sowing:
Trichocereus pachanoi / bridgesii / peruvianus
Lophohora williamsii / decipiens / fricii / jourdaniana / diffusa / alberto-vojtechii / koehresii
Myrtillocactus geometrizans
Ariocarpus fissuratus / agavoides / bravoanus / kotschoubeyanus / trigonus / retusus
Below are some impressions of my sowing of various Lophophora species in 2023
Seeds from Koehres-Kakteen.de
Sowing 02/15/2023 in a planting tent under the Viparspectra XS2000 and P600:
Germinated seeds after 4 weeks (mid-March):
Seedlings June 2023 (age approx. 4 months) are ready for transplanting.
Transplanting the seedlings into a Eurobox (60x40cmx10cm):
Covering the substrate with pumice and location in the tomato greenhouse (film greenhouse with shelves):
The seedlings are no longer kept moist to stimulate rooting, but dry spells are allowed. The box is perforated from below and this box is briefly dipped in water for pouring.
More updates to follow... :-)