Signs of Over-Fertilizing Dendrobium Orchids

Proper Fertilization

• With dendrobium orchids, it's best to follow the "weekly, weakly" principle, according to the American Orchid Society. This means you should fertilize the plants about once a week using a weak, or diluted, fertilizer solution. Use only about 1/4 of the recommended amount of fertilizer to prevent overfeeding. A balanced fertilizer, such as a 10-10-10 or a 20-20-20 works best for orchids.

Burning

• Too much fertilizer can cause the plant to develop burns. Dendrobiums have fleshy roots and leaves to help store nutrients, so when they're fed too much, the roots and leaves suffer first. Look for black tips or spots on the roots as a sign of too much fertilizer. The burn pattern usually travels up to the leaves, turning the edges brown or causing the leaves to develop random brown spots.

Salt

• Fertilizers contain salts, and your orchid can only process so much salt. When you've given your orchid too much fertilizer, you might see white, crusty spots on top of your sterile growing medium, around the pots drainage holes or along the outside of the roots. Replace the growing medium in potted orchids or spray the salts off the roots of outdoor plants to remove the salt before it can desiccate the plant.

Wilting Blooms

• Proper fertilization encourages healthy blooms, but over-fertilizing can cause the blooms to turn brown and wilt, basically rotting on the plant. This is a sign you might have given your plant too much nitrogen. Prune off the bad blooms so your orchid can focus on the existing blooms and leaves, and skip the next fertilization treatment. Orchids perform better on too little fertilizer than on too much. Giving your orchid a break can help it use up extra nutrients before you introduce more than it can handle.