Daylilies are the workhorses of the sunny border, but even these tough perennials stall out when the soil runs low on phosphorus, the key driver of flower initiation. A high-phosphorus formula can mean the difference between a sparse showing and a wall of color that lasts from early summer through fall.
I’m Mohammad Maruf — the founder and writer behind Gardening Beyond. Over the last several seasons, I’ve pored over bloom-booster NPK ratios, slow-release granular mechanics, and soil-microbe research, and I track aggregated owner feedback on dozens of formulations to separate what actually works from what just looks good on the bag.
Whether you’re a first-year grower or a daylily society member, knowing which NPK ratio matters most saves time, money, and disappointment. That’s why I curated this list of the top-rated fertilizer for daylilies options available right now.
How To Choose The Best Fertilizer For Daylilies
Daylilies are not heavy feeders, but they are phosphorus hogs when it comes to flower production. The wrong balanced NPK can push foliage at the expense of blooms, while a formula with too much nitrogen can lead to floppy leaves and fewer flowers. Here’s what to look for.
Prioritize the Middle NPK Number (Phosphorus)
A ratio like 10-54-10 delivers a massive phosphorus punch that signals the plant to form more scapes (flower stalks) and bigger blossoms. For daylilies, a middle number above 10 is ideal; anything below 8 will produce greener leaves but fewer blooms.
Choose Between Water-Soluble and Slow-Release
Water-soluble powders give you immediate control and fast uptake, perfect for a mid-season boost. Slow-release granules feed consistently over 4–6 weeks with less effort. Many growers use a slow-release granular at planting time and supplement with a water-soluble bloom booster every two weeks during peak flowering.
Check for Beneficial Microbes and Organic Certification
Products containing mycorrhizal fungi or soil microbes help daylilies absorb phosphorus and water more efficiently, especially in compacted or overworked soil. If you garden organically, look for the OMRI seal to ensure the formula meets certified organic standards.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Schultz Bloom Plus 10-54-10 | Water-Soluble | Heavy bloom boost | 10-54-10 NPK | Amazon |
| Schultz Slow-Release 12-24-12 | Granular Slow-Release | Long-lasting feeding | 12-24-12 NPK | Amazon |
| Lilly Miller Bulb & Bloom 4-10-10 | Granular Slow-Release | Bulbs & perennials | 4-10-10 NPK | Amazon |
| FoxFarm Happy Frog 6-4-5 | Organic Granular | Organic & microbial feeding | 6-4-5 NPK | Amazon |
| GreenView 10-10-10 | Balanced Granular | General garden use | 10-10-10 NPK | Amazon |
In‑Depth Reviews
1. Schultz Bloom Plus Water Soluble Plant Food 10-54-10
Schultz Bloom Plus is the clear winner for daylily growers who want immediate, visible results. With a staggering 10-54-10 NPK ratio, the phosphorus content here is among the highest available in a water-soluble powder, which directly triggers bud formation and larger flowers.
Users consistently report “flowers galore” and “tons of blooms” from their daylilies within a week or two of starting weekly applications. The formula also contains chelated micronutrients that help prevent common nutrient lockouts in alkaline or heavy clay soils, a typical issue in daylily beds.
The only catch is that because it’s water-soluble and very high in phosphorus, it requires more frequent application — every 7 to 14 days during the active growing season. That extra effort is worth it for the explosion of color you get in return.
What works
- Extremely high phosphorus for heavy bloom production
- Dissolves fast and evenly for immediate uptake
- Includes micronutrients for overall plant health
What doesn’t
- Requires weekly or bi-weekly reapplication
- Not a slow-release formula; needs consistent watering in
2. Schultz Slow-Release Bloom Fertilizer 12-24-12
If you want a “set it and forget it” option, Schultz’s slow-release granular is your best bet. The 12-24-12 ratio provides double the phosphorus of nitrogen and potassium, which is ideal for daylilies that need sustained feeding through their long bloom period.
Growers say they see results in just a few days with “more blooms that last longer” and “much more vibrant” foliage. The slow-release coating feeds for about 4 to 6 weeks, so you only need to apply it two or three times per season — once in early spring, once after the first flush of flowers, and optionally in late summer.
Because it’s a granular, you’ll need to scratch it into the top inch of soil around each fan and water it in well. It’s slightly less powerful than the water-soluble option on a per-gram basis, but the convenience makes it a favorite among busy gardeners.
What works
- Slow-release granules feed for weeks with one application
- Strong phosphorus boost for prolonged blooming
- Affordable price for a 3.5-pound bag
What doesn’t
- Needs soil incorporation and watering to activate
- Not as fast-acting as water-soluble formulas
3. Lilly Miller Bulb & Bloom Food 4-10-10
Lilly Miller’s Bulb & Bloom Food is formulated specifically for flowering bulbs and perennials, and daylilies respond beautifully to its 4-10-10 profile. The low nitrogen (4) prevents leafy overgrowth, while the balanced phosphorus (10) and potassium (10) promote strong roots and vibrant flowers.
This granular formula uses a slow-release mechanism that feeds for several weeks, making it a low-maintenance option for mass plantings or borders where you don’t want to fertilize every week. It’s also made in the United States and comes in a 4-pound bag that covers about 80 to 100 square feet.
The only downside is that the phosphorus level, while good, is not as extreme as the Schultz 10-54-10. For daylilies that are already in rich soil, this is more than adequate; for heavy feeders or sandy soils, you may want to supplement with a liquid bloom booster mid-season.
What works
- Low nitrogen prevents excessive foliage growth
- Slow-release granular for low-effort feeding
- Made for bulbs and perennials specifically
What doesn’t
- Phosphorus is moderate compared to other options
- May need supplementing in poor or sandy soils
4. FoxFarm Happy Frog All Purpose Fertilizer 6-4-5
For organic growers, FoxFarm Happy Frog is the standout choice. This 6-4-5 granular formulation is OMRI-listed and packed with beneficial soil microbes, including mycorrhizal fungi, that help daylilies access nutrients that are otherwise locked in the soil.
While the NPK isn’t bloom-specific (the phosphorus is lower than dedicated bloom boosters), the microbial activity more than compensates in degraded or compacted beds. Growers notice greener leaves and more consistent flowering, especially when the product is used as a top-dress in early spring and again in midsummer.
Because it relies on soil biology rather than synthetic salts, it works more slowly and gently than high-phosphorus solubles. If your daylilies are in good soil and you want a long-term, soil-building approach, this is the best choice. For immediate bloom maximization, you may want to pair it with a water-soluble bloom booster.
What works
- OMRI-listed organic with beneficial microbes
- Improves soil health and nutrient availability long-term
- Gentle, no-burn formula safe for all perennials
What doesn’t
- Lower phosphorus than dedicated bloom formulas
- Works slowly; not ideal for a quick color show
5. GreenView Multi-Purpose Fertilizer 10-10-10
GreenView’s 10-10-10 is about as staple as fertilizer gets — a perfectly balanced all-purpose granular that covers vegetables, flowers, trees, and shrubs. For daylilies, it provides a steady baseline of nutrients that supports both foliage and moderate flowering.
At 33 pounds, this bag is the most cost-effective option per pound, and it’s widely available with free delivery. Users across the Midwest report “very good results” on daylilies, hostas, and other perennials when applied once in spring and again in early summer.
The catch is that the equal NPK won’t push daylilies to peak bloom performance the way a high-phosphorus formula will. If you already have rich soil and just need maintenance feeding, this is a fine choice. If you want maximum flower count, you’ll want something more specialized.
What works
- Very large bag at an economical price per pound
- Versatile — works on entire garden, not just daylilies
- Granular format is easy to broadcast by hand
What doesn’t
- Equal NPK won’t maximize daylily bloom production
- Not organic; contains synthetic salts
Hardware & Specs Guide
NPK Ratio – What the Numbers Mean
The three numbers on a fertilizer bag (e.g., 10-54-10) represent Nitrogen (N), Phosphorus (P), and Potassium (K) by weight. For daylilies, the middle number (P) is the key: a high-P formula fuels bud formation, while a low-P formula supports foliage. The right ratio directly determines bloom density and size.
Release Mechanism – Soluble vs Granular
Water-soluble powders dissolve instantly and are available to the plant within hours, making them ideal for a quick bloom push. Granular slow-release formulas feed over 4–6 weeks through microbial breakdown or polymer coating. Granular is lower maintenance but slower to show results. Many daylily enthusiasts use a granular base and supplement with liquid during peak bloom.
FAQ
Should I use a high-nitrogen fertilizer on daylilies?
Can I fertilize daylilies during blooming?
How often should I fertilize daylilies with slow-release granules?
Are organic fertilizers better for daylilies?
Final Thoughts: The Verdict
For most gardeners, the fertilizer for daylilies winner is the Schultz Bloom Plus 10-54-10 because it delivers the highest phosphorus concentration in a fast-acting water-soluble powder that maximizes blooms with every application. If you want a low-maintenance slow-release option, grab the Schultz Slow-Release 12-24-12. And for organic growers who prioritize soil health, nothing beats the FoxFarm Happy Frog 6-4-5.