Holly Tone is an organic fertilizer and not inclined to 'burn'. Since by nature all organic fertilizers are slow release, the best time to apply to rhodies and other acid loving plants is in early spring as buds swell but before blooming. Immediately after blooming is fine as well but avoid heavy applications of nitrogen after about June 15th (organics do not tend to provide heavy doses of any plant nutrient, so typically very safe with these products).

btw, Holly Tone can be used on any broadleafed evergreen shrub and any needled conifer as well.

Gardengal, I've never used Hollytone. I've used Miracid and another product I can't remember offhand. But from what I read in the past about Rhododendrons it said to fertilize and prune right after flowering. Now that might be different when using a product like Hollytone. I will start using that next year. Thanks for the info.

Commercial rhododendron growers (and we have a LOT of them here in the PNW) typically suggest applying fertilizer in February (that would be the bud swell stage here) as a first choice or immediately after the bloom cycle if unable to do any earlier.

Rhododendrons and their other Ericaceae cousins do not require a lot of fertilizing, so it is not something one needs to do routinely. Generally, the suggestion is made to fertilize with an acidic formulation (like Holly Tone) if one's soil is not adequately acidic as that can bind up nutrients these plants need. Otherwise, a light application of compost around the drip line may be all that is required.

Thanks for the advice all. Gardengirl, you are a fountain of knowledge. I ended up fertilizing my rhodies w/Holly Tone a week or two before they bloomed. I was a little concerned about them after the extremely cold and harsh winter we had last year, especially since their leaves suffered winter burn. However, the flower show this spring has thus far been resplendent.

unclehippie: It's great that this year's flower show.has been resplendent, especially in Z5 after a very tough winter. I would point out, however, that Holly Tone, excellent fertilizer that it is, had nothing to do with this spring's flowers. One of Holly Tone's chief virtues is that it is slow acting. It will contribute to this summer's growth and next spring's display, but had no effect on this year's flowers. The buds for those were set last fall.