Both osmocote and miracle grow are great products to use on your plants, but they each have their pros and cons. Osmocote provides nutrients continuously throughout the whole growing season; however, if you do not purchase it during their early growth stages then your plants will likely need another source of nitrogen. Miracle grow can be used when planting new strawberry plants: if using chemical fertilizer though, only apply it after the first month or so of growth because nitrogen can burn or kill new plants if it is applied too early (before your strawberry plants are at least 4-6 inches tall).