When to Fertilize Chrysanthemums

Fertilising chrysanthemums at the right times makes the difference between average and outstanding blooms. These hardy perennials need nutrients for root development, leafy growth, and finally for bud and flower production. Applying the right fertiliser at the correct stage of growth ensures healthier plants and more vibrant displays. Below is a complete guide on when and how to feed mums throughout their lifecycle.

Early Growth and Establishment

The first feeding stage begins in early spring, as chrysanthemums emerge from dormancy or are newly planted. At this point, focus on building strong roots and foliage. Use a balanced fertiliser such as the
NPK 20-20-20 Plant Fertiliser. Its even ratio of nitrogen, phosphorus, and potassium helps establish resilient plants. Apply every 3–4 weeks during early growth to maintain steady development. Always water in well after fertilising to avoid burning roots.

Mid-Season Growth

As plants begin to fill out in late spring to early summer, continue feeding every 3–4 weeks with a balanced fertiliser. This sustains foliage and stem strength. Pinching back tips at this stage encourages bushier plants with more potential flowering stems. Consistent fertilising during this period ensures chrysanthemums have the energy reserves needed for their upcoming flowering season.

Chrysanthemum Fertilising Calendar

Season	Fertiliser	Purpose	Frequency
Spring	NPK 20-20-20 Plant Fertiliser	Supports root establishment and leafy growth after dormancy or planting.	Every 3–4 weeks
Summer	NPK 20-20-20 Plant Fertiliser	Encourages bushy growth, strong stems, and energy reserves before budding.	Every 3–4 weeks
Autumn	Advanced Formula NPK 4-18-38 + Calcium & Magnesium	Boosts bud and flower development, intensifies colour, strengthens stems.	Every 2–3 weeks until flowering ends
Winter	Light feed only (optional)	Plants are dormant — only a light application to recharge roots before cut-back.	Once, then stop until spring

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Budding and Flowering

The most important stage for fertilising chrysanthemums is when buds begin to form, typically in late summer. At this point, switch to a bloom-boosting formula such as the
Advanced Formula NPK 4-18-38 + Calcium & Magnesium. Its high phosphorus and potassium content enhances flower size, improves colour, and strengthens stems, while calcium and magnesium improve bloom durability and reduce deficiencies. Apply every 2–3 weeks until flowering finishes.

After Flowering

Once chrysanthemums finish blooming in late autumn, reduce fertilising. At this point, the plant is storing energy for dormancy. A light application of balanced fertiliser before cutting back stems can help recharge the root system, but avoid heavy feeding during winter. In spring, resume the cycle with a balanced fertiliser to restart growth strongly.

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Seasonal Feeding Schedule Summary

Think of chrysanthemum fertilising as a three-stage process: balanced feeding for establishment in spring, continued support through summer, and bloom-focused nutrition in late summer and autumn. Adjusting the fertiliser according to the plant’s needs at each stage ensures the best flowering results and long-term plant health.

FAQs – When to Fertilize Chrysanthemums

When should I start fertilising chrysanthemums? Begin in early spring with a balanced feed as new growth appears.
How often should I fertilise? Every 3–4 weeks during growth, then every 2–3 weeks during budding and flowering.
What fertiliser should I use for flowers? Switch to NPK 4-18-38 + CaMg once buds form for stronger, more vibrant blooms.
Should I fertilise after flowering? Apply lightly once after flowering, then stop during dormancy until spring growth resumes.
Can I over-fertilise chrysanthemums? Yes — too much nitrogen encourages leaves at the expense of flowers. Stick to a schedule and adjust by growth stage.