How to Fertilize Indoor Plants

Potted indoor plants require fertilizers as much as plants grown in open soil. But unlike outdoor gardens, container gardens require different methods of "feeding." Here are guidelines and tips to follow in fertilizing indoor gardens.

Instructions

Difficulty: Moderately Easy

Things You’ll Need:

• Various potting mixes
• Various types of fertilizers

Start With the Right Potting Mix

1. Know that different houseplants require different types of growing media or "substrate." Indoor plants are best grown in "soil-less" of "non-soil" potting mixes because regular garden soil is heavy and could contain insects and disease-carrying organisms. Examples of non-soil substrates are: vermiculite (expanded mica), perlite (puffed volcanic rock), lime-free river sand, peat and sphagnum moss, bark, clay, ground lava, limestone or basalt, horticultural grade charcoal and leaf mold.
2. Understand that there are acid-loving plants as well as alkaline-loving plants, so their growing media and fertilizer mixes must cater to their requirements. Examples of acid-loving houseplants are anthuriums and ferns; they thrive in acidic potting mix like peat moss, perlite and leaf mold. Alkaline-loving plants include most of the tropical varieties, and they prefer clay, loam or potting soil mixed with limestone or powdered lava.
3. Remember that many indoor plants must be planted in a substrate that drains well because their roots easily rot in stagnant water. Examples are orchids, bromeliads, cacti and succulents. Airy and loose substrates include perlite, bark, charcoal, cork, river sand and peat moss.

Fertilize With Care

4. Fertilize only during the growth period, typically spring and summer. Plants that require periods of dormancy should never be fertilized while they are "asleep." Some indoor tropical plants are in constant growth, so they require fertilizers all the time. Large and fast-growing plants need more fertilizer than small and slow-growing ones.
5. Refrain from fertilizing water- or light-deprived plants because the sudden onslaught of nutrients could actually kill them. Address their basic needs first. When they have recovered, that's when they can properly absorb fertilizer nutrition. Note that plants that thrive in low light require little or no fertilizer.
6. Always read the fertilizer package formulation and instructions. Choose formulas designed for houseplants, container gardens or indoor plants. Some very specific fertilizers are labeled for specific species of plants.
7. Carefully follow the recommended application in terms of quantity, frequency and delivery. It's better to under-fertilize than over-fertilize because too much can be harmful, even fatal, to the plants.
8. Watch for signs of over-fertilization like yellowing, deformed or burned leaves. To remedy an accidental over-fertilization, take the houseplant to the sink or outdoors and water it thoroughly, letting the water flow through the soil to "wash" the extra nutrients off.

Tips & Warnings

• The pH is the measurement of the acidity or alkalinity of the soil mixture. A pH of 7 is neutral, 0-6 is acidic, and 8-14 is alkaline. Acid-loving plants will have yellowish leaves and stunted growth if kept in alkaline soil; alkaline-loving plants will drop their leaves when the soil is too acidic. Know what your plants need and use the right soil mixture for successful growth.