Flower bulbs require nutritional supplements to keep the plants growing to their full potential from year to year. This is especially true with older bulbs that show a weak bloom performance. After the bulb's first year, its food supply is depleted. A plant food will help restore lost nutrients and prepare the plant for the upcoming blooming season.
Plant food nutrients
Nitrogen, phosphorus and potassium are the three important elements for bulb food. Nitrogen encourages leaf growth for bulbs. Phosphorus is essential to flower, seed and root development. Potassium improves general plant functions, like water absorption and protein production. For bulbs an N-P-K ratio should be higher in P (phosphorus) and K (potassium). A 1:2:2 is ideal, but this can vary depending on the type of bulb. There are two forms of bulb food, organic and chemical.
Organic bulb food
Organic refers to natural fertilizers that come from living organisms or natural minerals. They break down slowly and release nutrition to the plants over time. Buy organic fertilizer with the N-P-K ratio measured or acquire the organic components separately and combine. Bloodmeal, bonemeal, compost, aged manure, wood ash and phosphate rock are all natural fertilizers that make a sufficient bulb food when they are mixed in the correct ratios.
Chemical fertilizer is inorganic and made from synthetic chemicals. It will provide immediate nutrition that doesn't need to time to decompose. Chemical fertilizers are available in liquid, powder, granulated and time-released form. Look for a formula specialized for bulbs to eliminate the hassle of trying to find the right ratio of N-P-K.
Bulb plant food needs application twice a year. Springtime fertilizing is done when the green plant shoots start poking up from the ground, about six weeks before flowering. In the fall fertilizer is best utilized by the plant after it has flowered. Take the plant food, sprinkle it around the plant and rake it into the soil. Avoid placing the food near the bulb to avoid fertilizer burn. Spread roughly one tablespoon per square foot of earth or as directed on the package.
Natural bulb food
In addition to food added to the soil, the easiest way to re-energize bulbs is to remove faded flowers and leave the plant growth undisturbed until it is brown and dry. This allows the plant to continue photosynthesizing through the leaves. When the flowers are removed, the plant won't waste energy producing seeds. Apply a layer of mulch around plants to encourage natural release of phosphorus over time.