The Best Organic Fertilizers for Strawberries (and How to Apply Them)

If your strawberry plants are barely producing – or giving you soft, watery fruit – the problem’s probably in the soil.

Strawberries are picky. They like balanced nutrients, slightly acidic pH, and just the right kind of fertilizer. Too much nitrogen? Floppy plants. Too little potassium? Weak berries.

The good news? You don’t need anything fancy. Just a few natural ingredients – some from your compost pile, some from the garden store and a solid sense of when to use them.

In this article, I'll cover all of it. The best organic fertilizers. What they do. When to apply them. And what to avoid. Whether you’ve got everbearers or June-bearing types, we’ll lay it out in plain terms.

Let’s dig in.

Why Fertilize Strawberries?

Strawberries aren’t heavy feeders like corn or tomatoes, but they do need a steady diet to keep producing sweet, firm, flavorful fruit. A little care with the soil goes a long way.

If you skip fertilizing or throw on the wrong stuff, you’ll get problems. Pale leaves. Small, sour fruit. Or worse – big, watery berries that look nice but taste like wet cardboard.

Fertilization isn’t just about yield either. It affects how well the plants handle pests, diseases, drought, even winter. Strong plants bounce back. Weak ones… don’t.

And no, you can’t just dump on some 10-10-10 and hope for the best.

Strawberries have specific needs – low to moderate nitrogen, higher potassium, a touch of magnesium, and acidic conditions they actually prefer. It's about feeding the soil first, then the plant.

Understanding Strawberry Nutrient Needs

Here’s what strawberries actually want, nutrient-wise:

• Nitrogen (N): Helps with leaf growth. But too much? You’ll get tons of foliage and barely any fruit. So keep it in check.
  
• Phosphorus (P): Critical for root development and flower formation. This one really matters early in the season.
  
• Potassium (K): The big one for fruit quality. Boosts flavor, firmness, and shelf life. If your strawberries are soft or bland, low potassium could be the reason.
  
• Magnesium & Boron: Not as famous, but still important. Magnesium helps with photosynthesis. Boron – only in tiny amounts – supports fruit set. Most soils don’t lack these if you’re using compost, but they can show up short in worn-out beds.
  
• pH between 5.3 and 6.5: They like it a little sour. Too alkaline and nutrients get locked up, even if they’re technically “there.”

The bottom line? Strawberries thrive on balance. Not too rich, not too lean. Like they’ve got their own diet plan.

Best Base Fertilizers for Strawberry Beds

Before tossing anything on your strawberry bed, test the soil. It’s not overkill – it’s just common sense. You wouldn’t season a dish without tasting it first, right?

A good soil test tells you where you're starting from. Is the pH right? Are you short on potassium? Overloaded with nitrogen?

These things matter a lot more than people think. Especially with strawberries, which are oddly sensitive to imbalance.

You can grab a basic test kit at most garden centers, but if you want real numbers, send a sample to your local extension service or a reliable lab. It doesn’t cost much and saves you from throwing the wrong stuff at your plants.

Test results will show you your soil’s pH (aim for slightly acidic – between 5.3 and 6.5), nutrient levels, and whether you’re low on key micronutrients like magnesium or boron.

Start with Compost

Compost is the foundation. It feeds the soil, improves structure, and gives strawberries a stable source of nutrients. You don’t need a mountain of it – somewhere between 3 and 10 liters per square meter is usually enough.

If you’re using compost made from kitchen scraps or yard clippings, you’ll get fewer nutrient salts. That’s generally a good thing for strawberries.

Manure-based composts are richer, but they need to be fully broken down and aged to avoid problems.

Add Aged Manure (But Choose Carefully)

Aged manure is another excellent option – slow-release, full of organic matter, and great for long-term soil health. The type of manure matters, though.

Cattle manure is low in salts and gentle, making it a good fit for strawberries. Pig manure is more balanced and includes a bit of magnesium, which strawberries like. Horse manure is lighter in nutrients but still helps with structure.

Now, chicken manure? Not worth it. It’s loaded with nitrogen and salts and can easily overwhelm strawberry plants. If it’s in pellet form and extremely well-composted, maybe but it’s still risky.

Use manure in the fall if you’re digging it into the soil, or apply dried pellets in spring for a cleaner, more controlled option.

Supplementary Organic Fertilizers for Targeted Nutrition

Once your base is set with compost or manure, you might still need a little extra. Maybe the plants are slow to grow, or the leaves look pale, or the fruit just isn’t coming in strong.

That’s where targeted supplements come in – each one handling a specific nutrient need.

1. Horn Shavings or Horn Meal

This stuff is rich in nitrogen but low in just about everything else.

That makes it perfect if you’ve used compost as your main fertilizer and just need to bump up nitrogen a bit especially in spring when plants start pushing new leaves.

It releases slowly, which strawberries love, and it gently acidifies the soil at the same time. Win-win. Just don’t rely on it alone – it’s a supplement, not a full meal.

2. Tomato Fertilizer for Strawberries

Oddly enough, what works for tomatoes often works for strawberries too. Both need a solid dose of phosphorus and potassium, and a little magnesium to help with fruit quality.

That’s why organic tomato fertilizers (especially the slow-release ones) can be a great option.

Most of them come with clear directions on the package, which makes them easy to use even if you’re not deep into soil science. Just make sure you’re choosing an organic-certified one without synthetic salts.

3. Coffee Grounds

These are great for minor mid-season boosts. They don’t pack a lot of nutrients, but they do acidify the soil slightly, which strawberries appreciate. They also add a bit of nitrogen.

Just make sure they’re dry before applying – wet coffee grounds can get moldy and mess with your soil. You can even mix them with water (about a 1:1 ratio) and pour it around the base of your plants for a quick drink of mild nutrition.

4. Nettle Slurry

Nettle slurry is a bit of a secret weapon. It’s rich in nitrogen and potassium, and has silicic acid that helps plants resist pests and disease. But it can affect fruit flavor.

So, only use it early in the season, before any berries are forming. Once the plants start fruiting, put the nettle tea away.

Soil-Specific Organic Amendments (Use Only After Soil Test)

Sometimes the soil test comes back with gaps – low phosphorus, a magnesium shortage, or signs of a boron deficiency. That’s where these more focused amendments come in. You don’t use them all the time – just when something’s missing.

Phosphorus Sources

Bonemeal and rock phosphate both work to boost phosphorus. Bonemeal breaks down a little quicker, while rock phosphate is slow but steady.

Either one can support strong roots and flower formation if your test says you’re low.

Potassium & Magnesium

If potassium’s lacking, kelp meal is a gentle, organic fix. For both potassium and magnesium, sul-po-mag (also called langbeinite) does the trick especially if your soil is also a bit alkaline.

Nitrogen Supplements

If nitrogen is down across the board and compost or horn meal isn’t cutting it, bloodmeal or corn gluten can fill the gap. Bloodmeal is fast-acting. Corn gluten is slower but safer and also helps prevent weeds.

Micronutrient Fixes

Boron rarely runs low if you're using compost regularly but if your test says it’s deficient, a tiny bit of borax can help. Be careful with this one, though. Too much boron can harm your plants. Think “pinch,” not “scoop.”

Timing and Frequency of Fertilization Based on Strawberry Type

Getting the right fertilizer is one part of the puzzle. Knowing when to use it is the other and this varies depending on the kind of strawberries you’re growing.

Single-Bearing Varieties

These guys fruit once a year, usually in late spring or early summer. What most people don’t realize is that the flowers for next year’s fruit form in the autumn of the current year.

That means the most important fertilizing happens after the harvest, not before.

Late summer to early fall is the sweet spot. That’s when you apply compost or aged manure to build soil and encourage strong flower bud development for next year.

Skip fertilizing in spring. Seriously don’t do it. You’ll get lush, floppy leaves and oversized, watery berries. Plus, more problems with rot and mildew. It’s not worth it.

Everbearing Varieties

These are the overachievers – they’ll pump out fruit multiple times through the season. But they burn through nutrients faster too, which means you’ll need to feed them more often.

Start with a slow-release organic fertilizer in early spring. Once the second round of flowers appears (usually mid-summer), switch to an organic liquid fertilizer every 4 to 6 weeks until around mid-September.

After that, stop. Fertilizing too late can trigger new leaf growth just in time for frost to wipe it out.

The key is rhythm. Consistent feeding, without overdoing it, keeps everbearers productive without pushing them too hard.

Proper Fertilizer Application Methods

It’s not just what you apply – it’s how you apply it. Poor application can waste nutrients or even damage your plants. Thankfully, strawberries aren’t too fussy once you know the basics.

Granular Fertilizers

When you're using compost, manure, or dry organic blends like tomato fertilizer or bloodmeal, spread it around the base of the plant – not right up against the stems.

That direct contact can cause burn or rot, especially in moist conditions.

Once applied, lightly scratch it into the top inch or two of soil. You don’t need to till deeply – just enough to get it settled in. Then water it in well to start the breakdown process and help nutrients move toward the roots.

Liquid Fertilizers

For quick uptake or regular feeding of everbearing varieties, organic liquids (like diluted nettle tea or liquid tomato fertilizers) are a good fit.

Apply these in the morning, when the plants are actively taking up moisture. Avoid getting the leaves wet during midday sun – it can scorch them.

With liquid feeds, stick to the recommended dilution. More isn’t better – it just wastes product and stresses the plants.

For containers, this method is especially effective since nutrients can leach out faster from potted soil.

Post-Fertilization Watering Practices

Watering after fertilizing isn’t just a good idea – it’s essential. Dry soil after a feeding can trap nutrients where roots can’t reach them, or worse, cause salt buildup that damages the plant.

After applying any fertilizer – compost, manure, pellets, liquid – give your strawberries a deep soak. Not a quick sprinkle. You want the nutrients to move down into the root zone, not sit on the surface.

This is especially important after post-harvest fertilization in late summer. That moisture helps trigger root and crown development, which sets up strong flowering next season.

Just be careful not to overdo it. Constant sogginess can lead to root rot. What you're aiming for is moist, not muddy.

Feed your strawberries with care, and they’ll feed you in return – season after season.

Feeding strawberries doesn’t have to be complicated – but it does need to be intentional.

Start with good compost or aged manure to build a healthy soil base. Then, depending on what your plants and soil are telling you, bring in targeted fertilizers like horn meal, tomato blends, or even a dash of coffee grounds.

Skip the chicken manure, test your soil regularly, and don’t mess with late-season feeding unless you’re into frostbite foliage.

Everbearers need more frequent attention. Single-bearing types? Hit them hard after harvest, then leave them alone until next year. And always – always – water it in.

With the right timing, a few smart inputs, and a little patience, you’ll get strawberries that aren’t just bigger but better.

Frequently Asked Questions (FAQs)

What’s the best all-around organic fertilizer for strawberries?

Compost. Hands down. It improves soil health, adds slow-release nutrients, and creates the perfect base. If you need a little extra, pig manure or tomato fertilizer can round things out nicely.

Can I use chicken manure if it’s well-composted?

You can, but it’s risky. Even composted chicken manure tends to be too strong – too much nitrogen, too many soluble salts. Safer to skip it for strawberries.

How often should I fertilize strawberries in pots?

Start with a good potting mix and compost, then use a diluted organic liquid fertilizer every 4–6 weeks during the growing season. Container soil loses nutrients faster, so regular feeding helps.

Do strawberries really need acidic soil?

Yep. They grow best with a pH between 5.3 and 6.5. Anything much higher and they’ll struggle to absorb nutrients – even if those nutrients are present.

Is commercial strawberry fertilizer like Greenway Biotech truly organic?

Not exactly. It’s free of toxins and heavy metals, but the ingredients are synthetic mineral salts. It’s a clean product, just not certified organic.