Higgs Boson wrote:

Anybody use these for roses and/or other plants, both ornamental and
edible?

I have "regular" rose and other foods in granular form. Was just about
to apply & thought I'd try the spikes.

Just curious if those spikes deliver on their promise to supply long-
lasting food to roots.

I don't think they'ed work well for roses and other small shallow
rooted plants but they work very well for large deep rooted plants
like trees. A few of those large spikes pounded in around a tree's
drip line gives very noticable results and over a long time (years),
whereas surface fertilizing does virtually nothing for trees. In any
event don't over fertilize or you'll do more harm than good. Plants
don't need much fertilizer if any, they receive most of their energy
via photosynthesis.