Feeding: little, diluted, and never on a stressed plant
Feeding is not about more food, it is about food at the right moment. How much, when, and what happens if you overdo it: burnt tips are almost always too much fertiliser, not too little.
Feeding is not giving more: it is giving at the right moment, in the right dose. It is a well-meant gesture that, overdone, does more damage than hunger. Leaf tips going brown and dry are, in the great majority of cases, too much fertiliser — salts building up in the substrate and "burning" the fine roots — not too little. An underfed plant slows down and pales; an overfed one burns. When in doubt, less.
When to feed
Only during active growth, which for tropicals indoors runs roughly from March to September. In those months the plant makes new leaves and uses nutrients, so replacing them makes sense. In autumn and winter many tropicals slow down: feeding a stalled plant means pouring salts into a substrate nobody is consuming, and leaving them there to build up. In that season you stop, or you dilute very heavily.
How much. The practical rule is to halve the dose on the packet, always. Label doses are written for vigorous outdoor plants in open ground, not for a tropical in a pot in the sitting room. Better a little and more often — a very dilute feed with every second or third watering — than a full dose now and then, which risks salt shock. Liquid fertiliser diluted in the watering can is the simplest and most controllable way.
What never to feed
A plant that has just arrived or just been repotted: stressed or cut roots absorb badly and burn. A sick or infested plant: fertiliser is not medicine, and a struggling plant has no apparatus to use it. A plant with dry substrate: feeding dry roots scalds them — you moisten first, then feed. A new plant gets its first feed when the first new leaf appears, the signal that the roots have started working again, never before.
Which kind
For foliage plants — that is, almost everything in this catalogue — a balanced feed, or one slightly higher in nitrogen, the element that supports leaf growth, is right. No exotic formulas are needed: a good general liquid for green plants, diluted, does the job. Specific formulas only make sense in particular cases.
If you suspect you have overdone it — burnt tips, a whitish salt crust on the surface of the substrate or the rim of the pot — the remedy is a flush: water generously with plain water, running plenty of it through the pot to wash the accumulated salts out, and stop feeding for a month. It is easier to put right a hungry plant, which picks up as soon as you feed it, than one poisoned by salts, which takes weeks to clear them.