This year we conducted 200 test sowings amounting to 1/5th of our species overall and almost of 1/3rd of those species we test ourselves rather than just relying on the certification from the wholesaler/collector/grower.
As a result of these tests we have found that all of our cacti and succulent species continue to show excellent viability. We also tested all Acacia, Cassia, Delonix and Erythrina species again with very good results.
Cacti and Succulents
We didn't use the ziploc bag method this time, instead we went for the covered tray. Each batch was sown in a 7cm square pot of finely sieved (3mm) compost with a 25% addition of perlite to lighten up the mix. The pots were watered before sowing and no chemical fungicides were used. The seeds were all surface sown, then mist sprayed to settle in. The pots then went in seed tray (15 per tray) and had a domed cover put over the top. The whole thing then went on a heat mat giving a 10 Centigrade (18 F) lift over the ambient temperature this being in a greenhouse with a minimum temperature of 7.5 Deg C. Placed on the 2nd shelf of the staging, underneath the main layer, this gave the perfect amount of bright filtered light (around 40% of what was available). This mimics the ideal conditions where these seeds germinate in long grass or under shrubs. Temperatures on the mat varied from 17.5C to 37.5 C depending on the temperature in the greenhouse. 1st seedlings showed after 3 days, last ones after 6 weeks (for cacti) and 10 weeks (succulents). Percentages varied from 80% to 100% which, as ever, was species and age dependent. Anything with less than 50% we planned to withdraw from sale, happily none fell into this category.
Acacias, Cassia, Delonix, Erythinas
These had a different treatment to the one we normally use. Instead of boiling water we mechanically abraded every single seed used and then soaked them in tepid water until they swelled to at least twice the orginal size. We then sowed them as per the cacti - the only difference being 50% were put in bags the other 50% in trays as per cacti. Germination was even and good across the board and we saw 60 - 100% in every tested species. Where we noted a difference was in after care, those in the bags fared less well than those in the covered trays once they were exposed to fresh air - conclusion the bag method produces a more even germination but a less robust seedling - we recommend that the covered method is used UNLESS you have time to check every day and get any seedlings out in to the fresh air immediately they show the first leaves.