When to fertilize strawberries – expert tips to get the timing right for bigger harvests

Strawberries are a crop that always evoke thoughts of summer sun and you can maximize any potential harvest by making sure to properly fertilize your plants

Knowing how and when to fertilize your strawberries will ensure they grow strong and healthy and provide you with a veritable bounty of delicious juicy fruits in early summer for use in jams, desserts, or just to enjoy freshly picked in the yard.

A key part of learning how to grow strawberries is remembering to fertilize them. By choosing the right fertilizer and applying it at the correct time your plants will be happy and you will be rewarded come harvest time.

Drew Swainston

Drew is a former professional gardener in the UK who worked in productive kitchen gardens growing fruit, vegetables, and herbs for chefs. He has grown, maintained, and harvested many different varieties of strawberries – both growing indoors and outdoors – in the gardens.

When to fertilize strawberries for best results

There are two main times of year to fertilize strawberries, in early spring and fall. These are the prime times when the plants need a boost of growth and will benefit most from the extra nutrients. 

Strawberry plants start producing new growth when the soil temperature reaches around 50˚F – and adding fertilizer at that time gives them the nutrients they need to produce flowers and a high yield of delicious fruits.

Nathan Heinrich, a former propagation manager in California who now runs a botanical design company, says: ‘For a bumper crop of strawberries, start fertilizing in early to mid-spring.

‘Because your strawberry plants are expending so much energy growing leaves, roots, flowers, and berries in such a short period of time it is important to keep them fed with plenty of fertilizer starting in late March to early April.’

Nathan, who grew up on a farm in California that cultivated strawberries, adds that if you plant your strawberries in late winter or early spring, then fertilizer should be added ‘as soon as you notice' any new growth occurring. You can also plant strawberries in late summer into early fall, and new plants going into the ground then should be fed with a general fertilizer at the time of planting to encourage them to put down strong roots. 

Strawberries that are planted in hanging baskets, pots or containers, need extra attention and have to be fed at least every week throughout the growing season. Start this regime once they come into flower, and feed them with a high-potassium general fertilizer every week or fortnight.

The plants also benefit from another dose of fertilizer after they have finished fruiting and the last berries have been eaten, or you have planned how to store your strawberries and picked the plant clean. This will encourage root and leaf growth and ensure the plants are healthy enough for a good crop the following season. 

You can buy strawberry plants from Burpee or Nature Hills.

How to fertilize strawberries

Fertilizers for strawberries tend to come in dry or liquid forms and both can be applied in either spring or fall. All fertilizer should be applied at a rate recommended by the manufacturer as giving your plants too much of any feed can harm your plants. If you over-fertilize plants, it can burn the plant’s roots and it can be fatal.

Granular fertilizers can be spread by hand around your vegetable garden beds or containers and need to be watered in well after applying. Take care to avoid the granules touching the leaves or stems of the plants as it can cause them to burn. 

Liquid fertilizers are usually added to a watering can and then watered into the soil around the plants carefully, avoiding splashing the foliage as much as possible.

It is recommended that you clean your strawberries after picking them, to ensure that any soil, fertilizer, or other potential harmful substances are removed from the fruit prior to enjoying.

Choosing the right strawberry fertilizer

The best fertilizer for strawberry plants is a balanced one with an equal ratio of nitrogen, phosphorus, and potassium. It is important to understand a plant fertilizer label when deciding on feed for your plants, and the packaging will refer to those three nutrients as NPK. A balanced fertilizer will have an equal ratio of NPK, marked as 10-10-10 or 20-20-20 for example. This will provide your strawberry plants with all the vital nutrients they need for strong growth, healthy roots and good cropping of fruit.

If you wish to grow your strawberries without chemicals, there are organic fertilizers available that can give your plants all the nutrients they need. These include the likes of seaweed, bone meal, or chicken manure pellets. Homemade compost or well-rotted manure are also great options for strawberries as they provide all the nutrients required and release them to the plants over a long period of time.

Dr. Earth All Purpose Fertilizer | $17.50 from Amazon
This balanced fertilizer has a fairly even split of nitrogen, phosphorus, and potassium, making it a good option for your strawberry plants. If you prefer to garden using eco-friendly methods and products, this is a suitable organic choice for your plants too.  

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