Glad to get responses from the professionals! I use "non-organic" fertilizer because it is convenient and does not attract animals the way bone meal and fish fertilizer do. I don't have access to products sold to the nursery industry, but the Dark Weather Feed Mark mentions sounds very desirable for the range of bulbs I have, which are almost all winter-growing. For years I've been using Miracle-Gro Root and Bloom, a lower nitrogen formulation, at half strength and just 2 applications a year. As Robin recommends, the bulbs that are in pots (some are directly planted in a raised bed) are repotted frequently; I used to do it every other year, but mixing the soil has become physically challenging enough that I've fallen to every third year. I haven't added calcium to the mix but it contains a lot of ground white pumice, which has a higher pH than some other available components. Perhaps I should add Cal-Pril, a slow-release calcium product. We may be getting daytime temps into the 50s F in another week or so, and I have the barrel of rainwater ready to mix fertilizer then. Jane McGary, Portland, Oregon, USA On 3/5/2023 6:47 PM, Mark Akimoff via pbs wrote: > I have had this dilemma more than a few times over the past few years. The ammoniacal nitrogen form often messes with the pH in cold weather sometimes dropping it significantly, and at low temps the ammonia won’t nitrify and can cause toxicity. Using a nitrate form is better in the cold weather, in the greenhouse many of the bulbs are starting into very active growth now and do need some feeding. I recently discovered a product called Peters Dark Weather feed, it’s a 15-0-15 with cal mag and micros that is mostly nitrate nitrogen. I have been doing 50 ppm which is a pretty low dose but the plants have responded very well and I’ve even seen a few nutrient deficiencies corrected despite the temps in the 40’s. > > Mark > > Illahe Rare Plants > Salem, Oregon > > _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…