I’m guessing you clicked on this article about when to fertilize strawberries because, like me, you want to grow as many of the largest strawberries as possible. I think these summer treasures are worth all the attention we could give them! First, you’ll want to determine the type of strawberries you’re growing. Once you have that information, this article will help you learn the reasons to fertilize strawberries, how and when to fertilize strawberries based on the cultivar type, and other ways to keep your strawberries growing strong.

The benefits of fertilizing strawberries 

Strawberry plants produce fruit quickly and in abundance for their size. This is one of the reasons strawberries are so popular in the home garden. Other fruit-producing plants, like raspberries, take years before being harvest ready, and those plants take up more space. By going through the effort of fertilizing your strawberries, you’re boosting their fruit-bearing ability. Too much fertilizer isn’t good, but just enough will increase your plants’ yield as well as their ability to handle stressors from weather and pests.

Start with healthy soil

These perennials have shallow root systems. In fact, the University of Connecticut says more than three-quarters of a strawberry plant’s root system grows in the top 6 inches of soil. Their roots don’t go deep into the soil to mine nutrients the way other perennials do. For the best strawberries, begin with healthy soil. Before planting your patch, mix compost or composted manure into the top several inches of soil to boost soil organic matter, improve the soil microbiome, and make nutrients more available to strawberry plant roots.

One important aspect of healthy garden soil is crop rotation. There’s an additional crop-rotation consideration in planting strawberries. Avoid planting them in the same location that eggplants, potatoes, peppers, and tomato plants have recently grown. These nightshade-family plants can spread disease to your strawberries.

Choosing the best strawberry fertilizer

Before we talk about when to fertilize strawberries in your home garden, you need to know what strawberry cultivar you’re growing: June bearing, day neutral or everbearing. Here’s how to tell:

• June-bearing strawberries are the short-lived-perennial type that produce berries from late spring into early summer.
• Everbearing strawberries are perennials that are often grown as annuals. They produce fruit in the late spring and again in late summer.
• Day-neutral strawberries are also short-lived perennials that produce throughout the growing season. They offer fruit while the temperatures are between 45 and 85 degrees F (7 to 29 degrees C). This may mean the plants take time off from fruiting in July and August, if those are your hottest months of the year, but you could then have strawberries until the first frost.

Nitrogen, phosphorus, and potassium are the three main nutrients plants need. Potassium and phosphorus are most necessary for fruit and root development, whereas nitrogen sets up strong leaf growth. Strawberry plants need a balance of these nutrients. Many gardeners use a 10-10-10 fertilizer (that’s one with 10% nitrogen, 10% phosphorus, and 10% potassium), but I like to use an organic berry fertilizer to give my plants a boost.

Important micronutrients for strawberries are boron, calcium, and magnesium. Based on your soil test results, follow the recommendations to add a fertilizer that can provide these micronutrients to establish plant vigor.

Understanding nutritional needs 

The best strawberry fertilizer, of course, is the one that your plants specifically need. You can get this information with a soil test kit. Test your soil for nutrients and pH before you plant your strawberries, and then test again every year or two. Strawberries need an acidic soil pH of 5.3 to 6.5. If your pH is off, it’s best to amend it before the first year. Plan ahead, if possible!

When to fertilize strawberries – June-bearing types 

As strawberry plants emerge in early spring, your inclination will be to give them some help and fertilize them right away. When it comes to June-bearing types, springtime is not when to fertilize strawberries. Fertilizer applications at this time of year will encourage the foliage to grow and will produce soft berries. Thick foliage increases the risk of disease and causes fruit to rot. Instead, fertilize June-bearing strawberries after the last harvest of the season. Do this as part of your renovation process: trim back the leaves with hand pruners, cut remaining runners, thin the plants to their proper spacing, and pull weeds.

When to fertilize strawberries – Ever-bearing or day-neutral types 

If you’re growing everbearing or day-neutral strawberries, you can give in to the urge to fertilize them in early spring. You should also fertilize them another four to six times throughout the summer. Because these plants grow and produce flower buds and fruits throughout the season, they have a more steady nutrient requirement than the June-bearing types. 

How to fertilize strawberries 

You have the option of using a granular fertilizer or a liquid fertilizer. Granular fertilizers slowly release nutrients over time where liquid fertilizers offers more of an immediate nutrient boost. Liquid products are easily mixed in a watering can and watered into the soil around strawberry plants. Measure out granular fertilizers, according to the product label, and apply to the soil surface at the base of the plants. Or, scratch it into the top inch of soil.

Watering and mulching after feeding 

Like all plants, strawberries need adequate water to grow. The fruit itself is 92% water! The plant will have a growth spurt after fertilization, and adequate water is essential to making that happen. When you apply fertilizer, treat your plants as if they’re new transplants. Keep them well watered so their roots can take up as much as needed. 

Add straw mulch around the plants to protect their shallow root systems and maintain moisture in the soil. Additional bonuses of mulching are that your berries will have less dirt on them when it’s time to harvest and will be less prone to fruit rots. Plus a layer of mulch makes an excellent weed control.

Common mistakes to avoid when fertilizing strawberries 

Try to avoid these fertilization errors in your strawberry patch:

• Don’t fertilize strawberry plants out of season. Follow the guidelines for when to fertilize strawberries. 
• Don’t rely on fertilization as your only means of keeping strawberries growing strong. Soil health is vital here, whether you’re growing strawberries as annuals or perennials. As is plenty of sunlight!
• Don’t apply a slow-release fertilizer when your plants need nutrients immediately, and don’t apply an instant fertilizer when your plants need nutrient support over time.

For both your strawberry plants’ sake and your strawberry craving’s sake, learning when to fertilize strawberries will serve you well. With the advice in this article, you can make the right choice in fertilizers, you can apply those fertilizers at the right time and in the right way, and you can care for your strawberry plants well after fertilizing. 

It is true that these spring and summer gems will produce without fertilizing, but this small amount of effort pays in dividends. Especially for the perennial June-bearers, which I’ll continue to harvest from for a few years after planting. The time I spend establishing and feeding my plants is worth it.

For more information on growing a bumper crop of delicious strawberries, be sure to read these detailed articles:

• How to grow strawberries in pots and hanging baskets
• A guide to growing strawberry plants in raised beds
• How to plant and grow alpine strawberries
• The best spacing for strawberry plants