More fertiliser does not mean more growth. Dissolved fertiliser is a salt, and too much of it can burn root tips and leaf edges. Extension advice is firm: never mix a stronger solution than the label says.
When in doubt, less is more. University of New Hampshire Extension notes that over-fertilised plants can outgrow their pots too quickly or, in bad cases, become stunted and even die. Liquid and powder feeds act straight away, while slow-release pellets break down over weeks or months, so they are applied less often.
Timing matters as much as strength. Nebraska Extension lists plants that should not be fed: newly repotted plants, unrooted cuttings, resting plants and wilted plants. A wilted plant needs water first. A freshly repotted plant already has new mix and needs to settle its roots before it is pushed to grow. This is also why the earlier lesson on bringing plants home said not to fertilise straight away.
Slow-release pellets and some bagged potting mixes already contain fertiliser that lasts for weeks or months, so check the bag before adding more.
Key points
- Never exceed the label strength; when in doubt, feed less.
- Skip feeding newly repotted, unrooted, resting or wilted plants.
- Check whether your potting mix already contains slow-release fertiliser.
Try this
Look at the bag of the potting mix you use most. See whether it mentions added or slow-release fertiliser, and for how long it claims to feed.
Check yourself
Read more in the reference
Sources
Marking a lesson done is kept on this device only.