David, I strongly recommend not using any perlite or other synthetic products in your bulb soil. These products have no nutritional value and are likely to wash to the surface. I also recommend against using peat, because when you give your plants the necessary summer drying, it will be hard to rehydrate the peat. If you can, keep things simple. The pH is not particularly important; you don't need to raise the pH as long as you provide ample fertilizer (I use soluble Miracle-Gro "root and bloom" formula). Since you apparently have no source of natural organic matter, you can use a good potting soil such as Black Gold or Miracle-Gro for that component. I grow mostly what you're thinking about growing, and my soil mix is 2 parts coarse sand (quarts and basalt origin), 1 part ground pumice, and 1 part organic matter. For the organic I used to use forest topsoil, but I no longer have a deciduous woodland, so I just use potting soil. Granite grit is also a good amendment, as is quarter-ten crushed rock. Jane McGary, Portland, oregon, USA On 10/20/2020 3:58 PM, D V Andres via pbs wrote: > Hi, > I'm new to growing bulbs from seed. Currently I'm sourcing a cubic yard of > soil for a raised garden bed which I'll line with plastic planters and back > fill. I'll be growing a few Fritillaria, Calochortus, Iris, species along > along with others all native to the the Pacific Northwest. What I'm > considering is a 50/50 mix of a seed starting soil from a company called > Grab N Grow out of Santa Rosa that contains peat moss, perlite, 1/8″ minus > red lava sand, blood meal, bone meal, kelp meal, greensand, dolomite 10, > Azomite™, gypsum, oyster shell flour, and soil sulfur and mixing with 3/8'' > minus or number 3 sand. The premix soil is pH neutral and sterile and I can > buy it in bulk. If I go this option I wonder if I should add granite sand > or lava rock sand, etc. My other option is to mix 50/50 3/8'' minus sand > with peat moss but I'm not sure if the PH would be ok for seeds. Any > suggestions or recommendations would be greatly appreciated > Thanks, > David Andres > Angwin, CA > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > http://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>