Feeding raspberries: when to fertilise & the best feed for raspberries
As hungry feeders, raspberry plants require extra nutrients to support their vigorous growth and heavy fruiting. Learn more about when to feed raspberries and what to fertilise them with.
With their delicious fruits, it is not surprising that raspberries Rubus idaeus) are a homegrown favourite. However, to encourage a bountiful crop and help prevent disease both pruning raspberries and fertilising them are highly recommended. Read on to find out how and when to fertilise your raspberry plants and what fertiliser to use.
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Feeding raspberries: is it necessary?
Feeding raspberry plants is not strictly necessary, as if they are planted in relatively fertile soil, they will produce a crop come harvest time. However, raspberry plants use up a lot of energy producing their vigorous canes and delicious berries, especially when grown in pots and benefit greatly from supplementary feeding. Raspberries can also fall prey to pests and diseases, which can weaken the plants. You can find out more about raspberry diseases in our other article. Correctly fertilising raspberries can help keep them strong and healthy, so if disease or pests do strike, they are less likely to succumb. If the raspberry leaves turn yellow, it can often be caused by a lack of iron or magnesium, which fertilising not only helps prevent but reverses if necessary.
When to fertilise raspberry plants?
When you feed your raspberry plants is almost as important as whether you fertilise them or not, as there are key stages of a raspberry plant’s growth when they need the extra nutrition. These key times are upon planting and in early spring when the growing season begins.
Granular fertilisers are often slow-release and can provide nutrition for weeks or months on end. However, this does mean that they need to be applied with forethought and in advance of the flowering and fruiting, for which they are needed.
When growing raspberries in pots with limited soil, feeding is even more crucial, and nutrients need to be applied more regularly. On top of a granular feed in spring, it is best to apply a liquid feed every 4 weeks throughout the growing season to replace any leached or depleted nutrients. When repotting raspberry plants in spring, mix a slow-release fertiliser into the fresh compost to give the plants a boost for the coming season.
Should you fertilise raspberries in autumn?
There is a slight danger when feeding raspberries in autumn, as if the temperatures rise periodically, new growth may be stimulated leading to potential frost damage when the temperatures drop again. Furthermore, heavy winter rainfall can cause the nutrients to be washed away into waterways and negatively affect the local water system. Hence, only feed raspberry plants in spring or late summer.
Should you fertilise raspberries when planting?
Raspberry plants thrive when grown in a fertile, moisture-retentive and free-draining soil and ground preparation is a key part of planting raspberries. Whether planting bare root or potted plants, it is advisable to not only enrich the soil but also to provide the key nutrients necessary to help the new plant get off to a good start. Before planting, add some well-rotted manure or garden compost to the soil to help improve the soil’s structure and fertility. Furthermore, a general slow-release fertiliser or blood, fish and bone meal mix added on planting will provide some extra nutrition to support vigorous cane production.
Feeding Raspberries summary:
- Prior to planting, enrich the soil with well-rotted manure or compost
- On planting, add a slow-release general fertiliser
- Annually in early spring, apply a slow-release granular fertiliser high in potassium
- If required, give another slow-release application in June
- For container-grown raspberries, apply a slow-release fertiliser when potting up and feed monthly with a liquid fertiliser from June until September
What to feed raspberries: choosing the best fertiliser
When it comes to the best feed for raspberries, there are several different choices, from organic to synthetic options and those that are manufactured or homemade. Here is an overview of some of the most commonly used fertilisers for raspberries.
Raspberry organic fertilisers
Organic fertilisers are those that are derived from animal or plant sources. They contain nutrients, such as nitrogen, potassium and phosphorus, and other trace minerals, including iron and manganese that are essential for plant growth. There are many options available, ranging from homemade compost and well-rotted manure, which not only feed the raspberry plants but also help condition the soil, to commercially available slow-release pellets. If you have the space, making your own garden compost or comfrey liquid fertiliser is great; otherwise, high potassium fertilisers or manure pellets are widely available and suitable for feeding raspberries. If adding manure to enrich the soil, it must be well-rotted; as when applied fresh, its high levels of nutrients can burn and damage the plants.
Tip: granular fertilisers are often slow-releasing and can feed plants for up to 3 months. Take care when working them into the soil, as the roots can easily be broken.
Tomato feed for raspberries
Tomato feeds contain high levels of potassium and can be used to help encourage raspberries to flower and fruit. Our Plantura Tomato Food is made from 100% natural ingredients and can be applied in early spring or summer. It is slow release, feeding the raspberry plants for up to 3 months. Not only does it contain the necessary potassium and phosphorus to help promote flower and fruit production but also nitrogen to support the plant’s growth.
- Perfect for tomatoes, chillies, courgettes, cucumber & more
- For healthy plants & an abundant tomato harvest
- Long-lasting fertiliser that is free from animal products - child & pet friendly
When it comes to feeding raspberries grown in pots, a liquid fertiliser is easier to apply. It is diluted in water and given every 4 weeks when watering. Our Plantura Liquid Tomato Food contains the key potassium and phosphorus to encourage flowering and fruiting. The liquid food can be applied as soon as the first flowers appear.
- Perfect for tomatoes & other vegetables
- Liquid fertiliser for healthy plant growth & an abundant harvest
- Quick & easy application - child & pet friendly
Mineral fertilisers on raspberries
Mineral fertilisers can be provided in granular or liquid forms and are sometimes used for soft fruits. Synthetically derived from mined minerals or artificial forms, their water-soluble nutrients are often provided in high concentration and can be rapidly absorbed by plant roots, leading to quick results. However, due to their high concentrations, these fertilisers if misapplied, can lead to rapid over-fertilisation and plant damage.
Coffee grounds as a fertiliser for raspberries
As a common household by-product, spent coffee grounds can also be used to fertilise raspberry plants. Providing nitrogen and other trace elements, used coffee grounds can help support vigorous growth, but as they are acidic, only use in moderation and not after September.
As well as fertilising, raspberries need to be cared for in other ways to help encourage a good crop. Discover all our tips on growing and caring for raspberries.
