Chrysanthemums are popular garden plants, cherished for their vibrant and diverse blooms that signal the arrival of autumn. Achieving a spectacular display from these plants relies significantly on providing them with the correct nutrients. Proper fertilization ensures their overall health, encourages robust growth, and maximizes their flowering potential throughout the season.
Why Fertilize Chrysanthemums
Fertilizing chrysanthemums provides the building blocks for vigorous growth and abundant flowering. Proper nutrition contributes to vibrant blooms, enhancing their size and color. It also supports strong root systems, essential for anchoring the plant and absorbing water and nutrients. Healthy foliage results from proper feeding, aiding photosynthesis. This nutritional support leads to overall plant vigor and increased disease resistance.
Choosing the Right Fertilizer
Selecting the appropriate fertilizer for chrysanthemums involves understanding the NPK ratio, representing percentages of Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen primarily supports leafy growth and strong stems, contributing to overall size and greenness. Phosphorus is essential for healthy root development and flower production. Potassium fosters sturdy stems and contributes to overall health and resilience.
For general growth and during the active vegetative phase, a balanced fertilizer is recommended, such as a 10-10-10, 20-20-20, or 15-15-15 blend. Seedlings benefit from milder, nearly balanced formulations like 1-1-1, 2-2-2, or 3-3-2. As chrysanthemums approach blooming, shift to a fertilizer with higher phosphorus, such as NPK 0-52-34 or 10-26-26, to encourage robust flower development. Established plants benefit from high nitrogen during growth, then high potassium once flower buds are visible.
Fertilizers are available in various forms, each with advantages. Granular fertilizers, including slow-release and quick-release types, are applied to the soil and release nutrients over time. Slow-release granular options can provide nutrients for up to three months for sustained feeding.
Liquid or water-soluble fertilizers offer immediate nutrient availability, absorbed quickly through roots and foliage. They are mixed with water according to manufacturer instructions and applied as a root drench or foliar spray. Organic options, such as compost, leaf mold, blood meal, bone meal, and alfalfa, enrich the soil naturally. These amendments improve soil structure and drainage while gradually releasing nutrients, posing a lower risk of over-fertilization.
When and How to Fertilize
The timing and method of fertilization are important for chrysanthemum health and blooming. When initially planting, amend the soil with organic materials like compost for a nutrient-rich base. If transplanting divisions or nursery plants, wait a few weeks for them to establish root systems before applying fertilizer, as nursery specimens are pre-fertilized. For spring plantings, watering with a balanced liquid plant food aids establishment.
During the active vegetative growth phase in spring, after the last frost and when new growth reaches four to six inches tall, begin a regular feeding regimen. This period benefits from a high-nitrogen fertilizer to support robust foliage and stem development. Monthly applications of a liquid fertilizer can continue from early spring through mid-July.
As the season progresses and chrysanthemums approach their pre-bloom stage, usually in early to mid-summer when buds start to form, adjust the fertilization strategy. Fertilizing before flower buds fully develop promotes healthy roots and strong bud development. If you plan to overwinter chrysanthemums, a high-phosphorus fertilizer applied before buds set encourages strong root growth, which is important for winter survival.
After the initial flush of flowers, some gardeners apply another application to support continued blooming. Optionally, a final light feeding of compost or an all-purpose mild food can be applied six to eight weeks before the first projected frost date. For chrysanthemums discarded at season’s end, no further fertilization is necessary. For potted chrysanthemums overwintered indoors, suspend fertilization until new growth emerges in spring after they are moved back outside.
When applying granular fertilizers, spread them evenly around the plant’s base, ensuring they do not contact stems to prevent burning. After application, water thoroughly to help dissolve nutrients and move them into the soil.
For liquid fertilizers, dilute them according to manufacturer’s instructions; some organic liquid fertilizers may require significant dilution, such as a 0.5% solution. These solutions can be poured directly onto the root zone or sprayed onto the foliage.
Potted chrysanthemums require more frequent feeding than those in the ground, as nutrients leach out of containers more quickly with watering. Always apply fertilizers early in the day, avoiding midday sun, and prevent over-fertilization.
Troubleshooting Fertilization Issues
Recognizing signs of improper fertilization is important for maintaining healthy chrysanthemums. Under-fertilization appears as stunted growth, yellowing leaves, or poor bloom production. A lack of adequate nutrients can also lead to premature budding. These symptoms indicate the plant is not receiving enough essential nutrients.
Conversely, over-fertilization can cause damage to chrysanthemums. Common indicators include leaf burn (yellowing or browning on leaf tips and margins) and general wilting. Excessive fertilizer can lead to stunted growth, black or rotting roots, and a visible white salt crust on the soil surface. Too much nitrogen, in particular, results in an overproduction of weak, leggy stems and fewer flowers. This damage occurs because high concentrations of salts in the soil hinder the plant’s ability to absorb water, drawing moisture out of the plant.
To correct over-fertilization, flush the soil thoroughly with plenty of water until it drains freely from the pot or garden bed. This process leaches out excess nutrients.
For potted plants, if symptoms are severe or there are no drainage holes, repotting into fresh soil may be necessary. Any visible granular fertilizer or crusted topsoil should be removed.
After flushing, refrain from fertilizing for at least a month to allow recovery. To prevent future issues, always adhere to recommended application rates, consider using slow-release fertilizers, and water thoroughly immediately after applying any fertilizer. For under-fertilization, adjusting the feeding schedule and using balanced fertilizers helps the plant regain vigor.