The object of any bromeliad feeding program is to produce beautifully colored foliage and strong, deeply colored flower bracts.
Most of the bromeliads sold as houseplants are epiphytes, meaning they cling to trees and grow in midair. In the wild, their central cups act as reservoirs for both food and water. Plant and insect debris falls into the wet cup, where it gradually rots, supplying the plant with a steady diet of organic matter. Frogs and other larval insects also live in the cups, providing yet more organic matter (if you think about it, the wild bromeliad basically maintains its own compost pile).
In the home situation, it's next to impossible to duplicate this environment, unless you have steady access to warm rainwater, leaf and insect debris, and frogs and larval insects. So, falling short of ideal, here are the basic rules for feeding bromeliads. Keep in mind, however, that the different species require different approaches, so make sure to follow the species-specific tips:
- Use a weak liquid fertilizer during the growing season. Most well-balanced fertilizers will do. Avoid high nitrogen fertilizers as these will likely hurt the plant's ability to flower (unless you're aiming for nice foliage). Mix the fertilizer at 1/4 the label strength and apply with a spray bottle.
- Fertilize only during the active growing period. Fertilizing a dormant plant can burn the leaves.
- Don't put any kind of solid fertilizer (powder or pellets) directly into the central cup. This will burn the plant.
- If your plant is well-rooted, with healthy, extensive roots, you can top-dress the soil with slow-release pellets at the beginning of the growing season. Be aware, though, that bromeliads are naturally epiphytes, even they can be trained to feed through their roots.
Within these broad guidelines, it's important to remember that the different bromeliads have somewhat different requirements. After all, each of these species has adapted to living in a different environment, and your goal with each species might be different (you might want large flowers in one species, for instance). Follow these guidelines from the Bromeliad Society International for the individual species:
- Aechmea. Feed monthly during the growing season with a 20/20/20 fertilizer at half strength.
- Billbergia. Feed monthly during the growing season with a 20/20/20 fertilizer at half strength.
- Neoregelia. For best leaf color, use a low-nitrogen fertilizer at quarter strength in the pot only.
- Guzmania. Fertilize monthly during growing season with low-nitrogen liquid fertilizer at 1/4 to 1/3 strength. Slow-release pellets can be added to the soil, but not in the central cup. Do not use a fertilizer high in mineral salts.
- Tillandsia. Soft-leaved tillandsia types can be potted; hard-leaved types should be mounted. Spray hard-leaved types directly with low-nitrogen liquid fertilizer at 1/4 strength; soak occasionally. Treat soft-leaved types like neoregelia.