Signs you are feeding too much
Salts are the giveaway. Clemson HGIC describes a white film on the soil or a white crust on the rim and drainage hole as a sign of overfertilizing, sometimes with overwatering, and lists what the buildup does to the plant: reduced growth, brown leaf tips, lower leaves dropping and wilting. UF/IFAS adds that softened tap water brings salts of its own. The cure is to stop feeding for a while and flush the pot: run plain water through it until it pours freely from the drainage hole, which the Illinois Extension suggests doing every four to six months anyway.
What our plant guides recommend
Each guide stores the feeding rhythm and strength its sources give for that plant. Plug the strength into the calculator, and use the interval in the feed every field.
| Plant | How often | Strength | Winter |
|---|---|---|---|
| African violet | every 4 to 13 weeks | label rate | reduced |
| Air plant | every 4 weeks | quarter strength | reduced |
| Alocasia | every 4 to 13 weeks | label rate | none |
| Aloe vera | every 4 weeks | label rate | none |
| Amaryllis | every 1 to 2 weeks | label rate | reduced |
| Anthurium | every 1 to 4 weeks | quarter strength | reduced |
| Areca palm | every 8 to 13 weeks | label rate | none |
| Arrowhead plant | every 4 weeks | half strength | none |
| Basil | every 2 weeks | half strength | reduced |
| Begonia | every 2 weeks | quarter strength | none |
| Bird of paradise | every 1 to 2 weeks | label rate | none |
| Bird's nest fern | every 4 weeks | half strength | none |
| Bonsai | every 2 to 8 weeks | label rate | none |
| Boston fern | every 4 to 5 weeks | half strength | none |
| Bromeliads | every 4 to 13 weeks | half strength | none |
| Burro's tail | every 13 to 26 weeks | label rate | none |
| Cactus | every 4 to 5 weeks | label rate | none |
| Calathea | every 4 weeks | half strength | none |
| Cast iron plant | every 4 to 13 weeks | label rate | none |
| Chinese evergreen | every 4 weeks | quarter strength | none |
| Christmas cactus | every 4 to 8 weeks | half strength | none |
| Coleus | every 4 to 13 weeks | label rate | none |
| Croton | every 4 to 13 weeks | label rate | none |
| Cyclamen | every 4 weeks | label rate | reduced |
| Dieffenbachia | every 2 to 4 weeks | half strength | none |
| Dracaena | every 4 to 13 weeks | label rate | none |
| Echeveria | every 4 to 13 weeks | label rate | none |
| English ivy | every 4 to 5 weeks | label rate | none |
| Ficus Audrey | every 4 to 13 weeks | label rate | none |
| Fiddle-leaf fig | every 4 to 13 weeks | label rate | none |
| Fittonia | every 4 to 13 weeks | label rate | none |
| Gardenia | every 6 to 13 weeks | label rate | none |
| Haworthia | every 4 to 13 weeks | label rate | none |
| Hibiscus | every 1 weeks | label rate | none |
| Hoya | every 2 to 4 weeks | half strength | reduced |
| Hydrangea | every 8 to 9 weeks | label rate | none |
| Jade plant | every 13 to 17 weeks | label rate | none |
| Jasmine | every 4 to 13 weeks | label rate | reduced |
| Kalanchoe | every 4 weeks | label rate | reduced |
| Lavender | every 4 to 13 weeks | label rate | none |
| Lithops | every 8 to 13 weeks | half strength | none |
| Lucky bamboo | every 4 to 13 weeks | half strength | none |
| Maidenhair fern | every 4 weeks | half strength | none |
| Majesty palm | every 8 to 13 weeks | label rate | none |
| Meyer lemon tree | every 8 to 13 weeks | label rate | reduced |
| Mint | every 2 weeks | half strength | reduced |
| Money tree | every 4 to 13 weeks | label rate | none |
| Monstera | every 4 to 13 weeks | label rate | none |
| Monstera adansonii | every 4 to 13 weeks | label rate | none |
| Moth orchid | every 2 weeks | half strength | reduced |
| Norfolk Island pine | every 1 to 2 weeks | half strength | none |
| Olive tree | every 4 weeks | label rate | none |
| Oxalis | every 4 weeks | label rate | reduced |
| Parlor palm | every 8 to 13 weeks | label rate | none |
| Peace lily | every 6 to 8 weeks | quarter strength | none |
| Peperomia | every 4 to 13 weeks | half strength | none |
| Philodendron | every 4 to 17 weeks | half strength | none |
| Pilea (Chinese money plant) | every 4 to 13 weeks | label rate | none |
| Poinsettia | every 2 to 4 weeks | label rate | none |
| Polka dot plant | every 4 to 13 weeks | label rate | none |
| Ponytail palm | every 13 to 26 weeks | label rate | none |
| Pothos | every 4 to 9 weeks | label rate | none |
| Prayer plant | every 4 weeks | label rate | reduced |
| Rhaphidophora tetrasperma | every 4 to 13 weeks | label rate | none |
| Rosemary | every 4 to 13 weeks | half strength | none |
| Rubber plant | every 2 weeks | label rate | none |
| Sago palm | every 4 to 13 weeks | label rate | none |
| Schefflera | every 4 to 13 weeks | label rate | none |
| Snake plant | every 4 to 13 weeks | label rate | none |
| Spider plant | every 4 to 13 weeks | label rate | none |
| Staghorn fern | every 4 to 8 weeks | label rate | reduced |
| String of bananas | every 4 to 13 weeks | label rate | none |
| String of hearts | every 4 to 13 weeks | label rate | none |
| String of pearls | every 4 to 13 weeks | label rate | none |
| Succulents | every 4 to 13 weeks | label rate | none |
| Tradescantia | every 4 to 13 weeks | label rate | none |
| Venus flytrap | no fertilizer | none | none |
| Weeping fig | every 4 to 8 weeks | label rate | none |
| Yucca | every 4 to 13 weeks | label rate | none |
| ZZ plant | every 13 to 26 weeks | label rate | none |
Liquid, powder or slow-release
The calculator handles liquids and water-soluble powders, the forms Clemson says are often preferred because a dilute solution lowers the risk of burn. For powders, entering the label dose in grams also gives the nitrogen concentration: a gram of 20-20-20 in a liter of water makes about 200 parts per million of nitrogen. Slow-release granules, spikes and tablets are dosed per pot rather than per volume of water, so follow their label; the Illinois Extension notes most of them last three to four months. Never feed a plant whose mix is bone dry: water it first, then apply the fertilizer solution at the next watering.