How and When to Fertilize Strawberries for the Best Harvest

Boost your harvest with these simple tips on fertilizing strawberry plants.

To get the most out of your strawberry plants and produce a big harvest of luscious fruit, you must provide the proper balance of nutrients. Planting strawberries in rich, well-draining soil is a good place to start, but your plants must also be fertilized regularly to produce a healthy crop of berries. This guide answers your questions about when and how to fertilize strawberry plants to maximize the harvest and keep your berries growing strong.

Do a Soil Test

Whether you’re growing strawberries or another type of plant in your garden, it’s always a good idea to test the soil before adding any amendments. Garden soils can become depleted over time and can accumulate too many salts or other additives when fertilizer is applied too often. If you test the garden soil every few years, you’ll know exactly what’s going on in the garden and whether you need to add any amendments.

Soil testing kits are available online, but you can also have the soil tested by your local cooperative extension office for more accurate results. Soil tests can tell you exactly which amendments your garden needs and whether the pH of the soil needs to be adjusted. For proper growth, strawberries grow best in rich, well-draining soil with a pH between 5.3 and 6.5.

strawberries growing in garden

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Best Fertilizer for Strawberries

Like most plants, strawberries prefer rich soil, which is why many gardeners add compost or aged manure to their gardens before planting strawberries. When these products are mixed into the top few inches of the soil, they slowly release nutrients into the garden, providing ongoing support for the strawberries as they grow. Depending on the results of the soil test, you may also want to add other amendments or a slow-release fertilizer to the garden before planting strawberries.

The best fertilizer for strawberries is usually a 10-10-10 or 12-12-12 balanced fertilizer. If you keep an organic garden, choose from all-natural fertilizers, including blood meal, kelp meal, soybean meal, and alfalfa meal. Usually, granular fertilizers are recommended for strawberries, but you can also opt for liquid fertilizers, which are easier to apply and work particularly well for container-grown berry plants.

When to Fertilize Strawberries

Before planting strawberries, amend the soil with compost or aged manure, which act as slow-release fertilizer while the plants are getting established. After that, strawberry plants need additional fertilizer during the growing season, but when that fertilizer should be applied depends on the type of strawberries you grow: June-bearing or day-neutral strawberries.

June-Bearing Strawberries

June-bearing strawberries are usually grown as perennials, and they should be fertilized once a year in late summer to early autumn after you’ve harvested the last of the berry crop. Gardeners usually renovate (thin) mature June-bearing strawberries about once a year in late July or August, and this is a great time to apply fertilizer. Avoid fertilizing June-bearing strawberries in spring, as this can result in overly soft berries and promote the spread of plant diseases.

Day-Neutral Strawberries

Day-neutral strawberries are often cultivated as annuals, so they have slightly different fertilizer requirements. After planting, day-neutral strawberries produce an initial flush of flowers that are typically pruned away so the plant can focus its energy on leaf and root development. However, when day-neutral strawberries begin to flower again in mid-summer, it’s time to start fertilizing the plants.

Fertilize day-neutral strawberries as soon as you see the second flush of flowers, and then apply fertilizer at six-week intervals until September. If you overwinter day-neutral strawberries, fertilize them in the spring of their second year and then apply a second dose of fertilizer in mid-summer.

No matter what type of strawberries you grow, don’t fertilize the plants late in the season. A late dose of fertilizer can cause the plants to produce new leaves, making them much more vulnerable to frost damage.

How to Fertilize Strawberries in Garden Beds

The amount of fertilizer the strawberries need depends on the type of fertilizer you use, so consult the instructions on the fertilizer packaging to determine how much to apply. A good rule of thumb is that a 20-foot row of strawberries needs about 8 ounces of granular fertilizer for proper development.

Both granular and liquid fertilizers work for strawberries grown in garden beds, but liquid fertilizer usually needs to be applied more frequently. If you’re using granular fertilizers, broadcast the fertilizer by hand around the base of the plants and scratch it into the soil surface using a hand rake. After application, water the granular fertilizer into the soil. Then double-check to ensure the granular fertilizer isn’t directly touching any plant stems, as this can cause plant tissue burn or rot.

How to Fertilize Strawberries in Pots

Strawberries planted in pots have less access to soil nutrients, so it’s even more important to ensure they receive the nutrients they need. One way to do this is to grow container strawberries as annuals, replacing the potting mix and purchasing new plants every year. This approach limits the spread of diseases and guarantees your plants aren’t growing in depleted soil.  

While granular fertilizers can be applied to container-grown strawberries, liquid fertilizers are usually easier to work with and are less likely to build up in containers. Liquid fertilizers can be applied with a sprayer or added to a watering can and applied as part of your regular watering regimen.

Although liquid fertilizers are easier to apply, they must be used more often than granular fertilizers because they wash out of plant pots more readily. Apply liquid fertilizer in the morning and avoid spraying it on plant leaves when the sun is high overhead, as this can result in leaf damage.

Frequently Asked Questions

  • What fertilizer makes strawberries sweet?

    Strawberries need a balance of nutrients to grow properly, but potassium is particularly important for enhancing the sweetness of berry crops. For this reason, if you want the tastiest and sweetest strawberries, select a balanced fertilizer with plenty of potassium.

  • How do you increase strawberry yield?

    A well-timed application of fertilizer is one of the best ways to increase the yield of strawberry plants. You can also enhance the harvest by snipping away extra runners from your plants and making sure the strawberries receive a proper balance of light and water.

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