Bone meal helps transplants and bulbs put down roots.
Contested
Bone meal isn't a rooting tonic. It's phosphorus, and unless a soil test shows your soil is short of it, adding more won't grow better roots — phosphorus hardly moves in soil and stays locked up in neutral or alkaline ground anyway. Plant at the right depth, water evenly, and soil-test before adding phosphorus; too much can even set back the fungi that help roots.
What is actually known
Bone meal is mostly phosphorus, and phosphorus genuinely is involved in root development — that is where the belief comes from. But it rests on two shaky steps. First, most established garden soils already hold plenty of phosphorus; unless a soil test shows a real deficiency, adding more does nothing for rooting. Second, phosphorus barely moves in soil and bone meal only releases it as it slowly breaks down, mainly in acidic soil — so scattered in a planting hole at neutral or alkaline pH it is largely locked up and unavailable this season anyway. Excess phosphorus is not harmless either: it can suppress the mycorrhizal fungi that actually help roots forage. The levers for strong roots are the right planting depth, even moisture, and not overfeeding — and a soil test before adding any phosphorus, because you cannot tell by looking.
Evidence: not yet confirmed against its 1 source.
what this rests on - one pointer
phosphorus is immobile in soil and rarely limiting in established garden beds; excess P can suppress mycorrhizae; soil-test before adding phosphorus — extension consensus
When would that grow at your place? →
Cite this page
Milpa Gardens. "Bone meal helps transplants and bulbs put down roots." Evidence grade: Contested. https://milpa.garden/beliefs/bone-meal-bulb-fertilizer/
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