Wicked Growth · Fertilizer Guide
Annual Flowers Fertilizer
NPK 15-30-15Non-Organic
Old Cobblers Farm™ Ground Flower Fertilizer for Flowering Annuals features a powerful 15-30-15 NPK ratio, designed to deliver maximum flower production and deep root development. With high phosphorus content (30%), this fertilizer is ideal for flowering annuals that need a boost during active growing and blooming phases. The fast-actin...
Shop Wicked Growth →Guaranteed Analysis
Nutrient Breakdown
N · Nitrogen
15%
15% Nitrogen promotes strong green growth
P · Phosphorus
30%
30% Phosphorus supports root development and prolific flowering
K · Potassium
15%
15% Potassium enhances plant resilience, stem strength, and bloom longevity
Derived from: Urea, Monoammonium Phosphate (MAP), Muriate of Potash (MOP), Pelletized Lime
Overview
What It Is
Old Cobblers Farm™ Annual Flowers Fertilizer is a high-phosphorus commercial fertilizer with a 15-30-15 NPK ratio. The 30% phosphorus content — the highest in the Wicked Growth lineup — is specifically calibrated for flowering annuals that complete their entire lifecycle in a single season and need maximum bloom energy.
Gardeners choose this formula because annuals have a limited window to flower and set seed. High phosphorus drives prolific blooming and strong root establishment, while balanced nitrogen and potassium support healthy foliage and plant resilience throughout the growing season.
Gardeners choose this formula because annuals have a limited window to flower and set seed. High phosphorus drives prolific blooming and strong root establishment, while balanced nitrogen and potassium support healthy foliage and plant resilience throughout the growing season.
Crop Fit
Best For
Petunias reward you with bigger, longer-lasting blooms. Marigolds achieve stronger flowering and foliage balance. Impatiens get boosted blooms in shady spots. Zinnias brighten beds with prolific, colorful flowers. Geraniums develop lush blooms and compact growth. Begonias (especially tuberous) benefit from extra phosphorus for blooming tubers. Cosmos produce tall stems and large blooms with phosphorus support. All 20 recommended annuals are heavy bloomers that respond dramatically to high-phosphorus feeding.
Application Rates
How Much to Use
| Garden & beds | 1 tbsp per sq ft |
|---|---|
| Lawn | N/A — formulated for annual flower beds, not turf |
| Trees & shrubs | N/A — formulated for annual flowers, not trees |
| Containers | 1 tsp per 6-inch pot; adjust proportionally for larger containers |
| Frequency | Every 4-6 weeks during growing season |
Step by Step
How to Apply
1
Pre-Moisten Soil
Water soil lightly if dry before applying fertilizer to avoid fertilizer burn on tender annual roots.
2
Measure
Measure fertilizer using recommended quantities for your bed size or number of plants.
3
Apply
Evenly apply to the soil surface around plant bases, keeping granules off stems and foliage.
4
Incorporate
Gently rake into the top 1–2 inches of soil to improve contact and reduce runoff.
5
Water In
Water thoroughly with a watering can or hose spray nozzle to activate nutrients and move them to roots.
For garden beds, use 1 tablespoon per square foot of garden space. For container plants, use 1 teaspoon per 6-inch pot and adjust proportionally for larger containers. Apply at planting or when new growth begins in early spring, then reapply every 4-6 weeks during growing season. Avoid late-season feeding to help plants harden off before dormancy.
Handling & Timing
Safety & Season
Safety & Storage
Store in a cool, dry place away from children and pets. Wear gloves if preferred during application. Keep away from water sources to prevent nutrient runoff.
Seasonal Notes
Apply initial dose at planting or when new growth begins in early spring. Reapply every 4-6 weeks during active growing season. Avoid late-season feeding to help plants harden off before dormancy. Best results when soil has warmed to mid-spring temperatures.
In Context
How It Compares
With 30% phosphorus, this is the highest-P formula in the Wicked Growth lineup — double what balanced blends like 10-10-10 provide. It's purpose-built for annual bloomers, unlike general-purpose fertilizers that spread nutrition evenly across growth types.
Answers
Frequently Asked Questions
What is the best fertilizer for annual flowers?
The best fertilizer for annual flowers is a high-phosphorus formula like 15-30-15 that powers prolific blooming and strong root establishment. Annuals have a single season to grow, bloom, and set seed, so they need intense nutritional support — especially phosphorus — to maximize flower production. The 30% phosphorus drives explosive bloom counts, while nitrogen (15%) supports lush foliage and potassium (15%) enhances bloom color and longevity. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 is specifically designed to help petunias, marigolds, zinnias, impatiens, geraniums, and other annuals produce their best displays all season long.
How often should I fertilize annual flowers?
Fertilize annual flowers at planting time and reapply every 4–6 weeks throughout the growing season. Annuals are heavy feeders that bloom continuously and deplete soil nutrients quickly. Container-grown annuals may need even more frequent feeding — every 2–3 weeks — because nutrients leach rapidly from pots with regular watering. Stop fertilizing in late summer as plants naturally wind down. Consistent feeding is the single biggest factor in keeping annuals blooming from spring through fall. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 delivers fast-acting, bloom-boosting nutrition with every application.
What fertilizer makes zinnias bloom more?
Zinnias bloom most prolifically with a high-phosphorus fertilizer like 15-30-15. Phosphorus is the nutrient most directly responsible for flower bud formation and bloom production. Apply at planting and reapply every 4–6 weeks during the growing season. Deadheading spent blooms also encourages zinnias to produce more flowers. Avoid excessive nitrogen, which promotes tall, leafy stems with fewer blooms. A balanced approach with bloom-boosting phosphorus produces the most colorful, abundant zinnia displays. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 supercharges zinnia bloom production for vibrant, cutting-garden-quality flowers.
Is 15-30-15 good for petunias and geraniums?
Yes, 15-30-15 is ideal for petunias, geraniums, and other flowering annuals that bloom continuously throughout the season. The high phosphorus content (30%) directly fuels flower production, while nitrogen supports lush green foliage and potassium improves bloom longevity and plant resilience. Petunias and geraniums are especially heavy feeders that respond dramatically to regular phosphorus supplementation — you will see noticeably more blooms with richer color. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 is formulated specifically for flowering annuals including petunias, geraniums, impatiens, marigolds, and calibrachoa.
What is a high phosphorus fertilizer for flowers?
A high phosphorus fertilizer for flowers has a middle NPK number significantly higher than the other two — like 15-30-15, 10-20-10, or 5-10-5. Phosphorus is the nutrient most directly responsible for root development and flower production. It fuels the energy transfer processes within the plant that drive bud formation, bloom opening, and seed production. For annuals that need to bloom fast and hard, a formula like 15-30-15 delivers maximum bloom-boosting phosphorus. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 is one of the most concentrated bloom-boosting fertilizers available for flowering annuals.
Can I use 15-30-15 on hanging baskets?
Yes, 15-30-15 works well on hanging baskets filled with flowering annuals like petunias, calibrachoa, verbena, lobelia, and fuchsias. Because hanging baskets dry out and leach nutrients quickly, they benefit from the concentrated phosphorus that drives continuous blooming in limited soil volumes. Apply at planting by mixing into the soil, and reapply every 2–4 weeks during the growing season. Use slightly lower rates for small containers to avoid salt buildup. Old Cobblers Farm™ Wicked Growth Annual Flowers Fertilizer 15-30-15 keeps hanging basket annuals blooming vigorously from spring through first frost.
What NPK ratio is best for flower beds?
For annual flower beds, a high-phosphorus ratio like 15-30-15 maximizes bloom production. For perennial flower beds, a balanced 10-10-10 provides steady, all-purpose nutrition year after year. For bulb beds, a formula like 5-10-10 supports root establishment and spring flowering. The best ratio depends on what you are growing and what stage the plants are in. Phosphorus is always the most critical nutrient for flowering. Old Cobblers Farm™ offers specialized formulas for annuals (15-30-15), perennials (10-10-10), and bulbs (5-10-10) to match the specific needs of every flower garden.
