Phosphorus & Potassium Fertilizer | P-K Supplement

Phosphorus and Potassium Fertilizer

4.4 · 288 reviews

Some feeding programs lean heavily on nitrogen and supply less of the other two main nutrients than flowering and fruiting plants use. Our liquid Phosphorus and Potassium Fertilizer adds phosphate and potash with no nitrogen at all, alongside the regular feed you already use, for gardens, containers and beds.

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What growers are saying

“I needed a fretilizer that was high in potassium and phosphorous with no notrogen. This fertilizer fit the bill. Just what I needed for my pepper plants to start producing more fruit again. I would definitely recommend this product. I like that it is kelp based as well.”
James C. · Verified buyer · Oct 1, 2026

“Best multi bloom booster I’ve used. At Age 68, I have used quite a few.”
Tom C. · Verified buyer · Sep 28, 2026

When your plants may benefit from added phosphorus and potassium

If a soil test for your garden shows available phosphorus is low during active root and shoot growth

When your fruiting or flowering plants have a confirmed potassium need that their current fertilizer program does not meet

If your established container crop has exhausted available phosphorus or potassium and a nutrient assessment indicates supplementation

When your existing fertilizer supplies sufficient nitrogen but a test-based feeding plan calls for additional phosphorus and potassium

More phosphorus does not automatically mean more flowers. Test nutrient availability before adding 0-10-10, especially in soil where phosphorus can build up.

Results you can see

Feeds foliage for deeper color and a brighter, more lively look.

Encourages fresh leaf and stem growth for a fuller, thriving plant.

Supports healthy, resilient roots that absorb nutrients more effectively.

How to use

Watering can

2 Tbs (30mL) per gallon of water

Spring & Summer: every 1-2 weeks · Fall & Winter: every 4 weeks
Hose-end sprayer

Set dial to 1 oz (30mL) setting

Spring & Summer: every 1-2 weeks
Leaf misting (optional)

1 tsp per quart (32 oz) of water, spray on leaves

every 1-2 weeks

What's inside

The 0-10-10 ratio delivers phosphorus and potassium with no nitrogen, aimed squarely at flowering, fruiting, and root development rather than leafy growth — 10% available phosphate backs bud set, flower formation, and root strength, while 10% soluble potash drives bloom size, fruit quality, and your plant's water and stress handling. Leaving nitrogen out keeps your plant from redirecting energy into foliage during the stage when you want flowers and fruit instead.

Beyond NPK: this is a focused phosphorus-and-potassium feed, not a full-spectrum blend, so it doesn't carry the calcium, magnesium, and micronutrient package of a complete fertilizer. It does include 2.0% sulfur, which supports plant health and nutrient use, plus sea kelp (Ascophyllum nodosum) for natural growth compounds that aid uptake. Because there's no nitrogen or micronutrient content, pair it with your regular feeding during bloom and fruit set rather than using it as a standalone fertilizer.

Frequently asked questions

When should I use it?

Phosphorus and Potassium Fertilizer is a companion feed, 0-10-10 with 2% sulfur, that adds flowering and rooting nutrients on top of your regular fertilizer without adding any nitrogen. Use it on the same rhythm as that regular feed: every week or two in spring and summer, about once a month in fall and winter, at 2 tablespoons per gallon or the 1-ounce setting on a hose-end sprayer.

Is this slow-release or fast-acting?

Fast-acting. It’s a liquid, so the phosphorus and potassium reach the soil already dissolved rather than releasing over months from a granule. That matters for phosphorus especially, which moves slowly in soil; delivering it in solution at the root zone, on a repeating schedule, gets it to your plant while it’s budding and flowering.

Is this a high-phosphorus fertilizer?

Yes: 10% phosphorus and 10% potassium with no nitrogen, which is what 0-10-10 means. It’s the feed to reach for when you want to push flowering, fruiting or root development without adding more leafy growth, for example on a plant that’s all foliage, or one already on a nitrogen-rich base fertilizer. It also carries 2% sulfur.

What do phosphorus and potassium actually do?

Phosphorus supports root development and the formation of flowers and fruit. Potassium supports your plant's overall resilience: stem strength, water regulation and how it copes with heat and cold. Nitrogen, which this formula leaves out, drives leafy growth. So Phosphorus and Potassium Fertilizer gives you the first two on their own, for the times you want more bloom and root and less leaf.

Can I use it as my only fertilizer?

No. It has no nitrogen, and every plant needs some to grow. Phosphorus and Potassium Fertilizer is designed to work alongside your regular feed, including any other TPS fertilizer, as a top-up for roots and flowers rather than a complete diet. Use both, on the same schedule.

Will this burn my plants?

Phosphorus and Potassium Fertilizer is a dilute liquid feed, and dilution is what matters here. Fertilizer burn happens when concentrated salts sit against the roots: too much product in too little water, or granules piled at the base of a plant. Mixed at 2 tablespoons per gallon and applied every week or two in season, the nutrients arrive in solution at a strength the roots take up as they water. Keep to that mix and water it in as part of a normal watering.