How to feed plants
Feeding plants means adding nutrients which help them to grow. This can be supplied by foliar feeding, but is typically achieved by feeding the soil or potting compost. While most plants grown in containers benefit from feeding with fertilisers, this is seldom needed by plants growing in the ground.
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Quick facts
- Most UK soils do not need fertilisers to grow healthy plants. However, feeding may be needed in some instances. Healthy soils feed plants adequately without needing additional fertiliser
- Most ornamental plants, especially established trees and shrubs, do not need any feeding
- Plants in containers need regular feeding to flourish
- Feeding with organic mulches produced at home such as homemade compost is beneficial for the environment
- Organic mulches improve soil structure and conserve soil moisture, reducing the need to water
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Do I really need to use fertiliser?
No. Most ornamental plants growing in the ground and well mulched vegetable beds do not need regular feeding with fertilisers. Apart from being costly, nitrogen-rich fertilisers encourage lush growth that can make plants less resilient to adverse weather. Softer growth is also more susceptible to pests and diseases. Therefore, fertilisers should only be used to correct a deficiency.
Buying fertilisers, or mulches (unless homemade or sourced from a local supplier) for your garden have a negative environmental impact. The manufacturing, processing, packaging and distribution all contribute to a carbon footprint. Likewise, fertiliser overuse, whether organic or inorganic, can lead to leaching, a washing out of soil
How do I feed plants without fertilisers?
Organic mulch acts as fertiliser, so the goal is to ‘feed’ the soil, rather than the plants themselves. Applying mulch works as ‘soil improvement’, a process which boosts soil health. Overtime this creates a nutrient-rich, biodiverse soil that supports a diversity of plant life.
To do this, apply organic mulches to the soil such as:
- Homemade garden compost
- Well-rotted manure
- Manure-based soil conditioners
- Plant-based soil conditioners e.g. anaerobic digestate
- Council compost made from green waste
To raise fertility, you don’t need to cover your whole garden with mulch every year. Aim for around one quarter of the borders each year, prioritising fruit and vegetable beds. Spread it over sections of your garden around 5-7cm deep.
How does it work?
Organic mulches are a good source of plant nutrients, which are gradually released over time. As the organic matter in mulch breaks down, it releases stored nutrients and supports the soil microbiology, which in turn supports plants.
Although they contain lower concentrations of plant nutrients compared to most fertilisers, they are applied to soil in larger quantities.
Regular application of mulch maintains soil fertility, which in most instances, reduces or removes the need to apply fertilisers.
Composting
How plants absorb nutrients
How to mulch with organic matter
Organic matter: how to use in the garden
Which plants need fertiliser?
The following benefit from using fertilisers:
- Seedlings and cuttings
- Houseplants
- Plants in containers: fruit, vegetables and ornamental plants
- Fruit and vegetables in the ground unless using no-dig method
- Sick plants and plants showing nutrient deficiencies. Identify the cause first. Consider soil analysis or specialist leaf-tissue analysis for high value plants or crops
Feeding seedling and cuttings
There is a limited amount of nutrients available to plants in peat-free seed and cutting composts. Young seedlings and cuttings raised in peat-free compost benefit from early feeding – once the seedlings develop the first seed leaves and cuttings begin to grow.
Ideally, use a higher nitrogen (N) and lower potassium (K) feed, such as Elixir Gardens High Nitrogen Liquid Plant Food (20–0–10). However, using a general-purpose fertiliser with similar nitrogen (N) and potassium (K) values, for example: Miracle-Gro® All Purpose Concentrated Liquid Plant Food (7–3–5) will still help. Check the label recommendations carefully as young plants and seedlings usually require a weaker concentration of fertiliser to avoid damage.
Delay using high potassium fertilisers such as tomato feed that to encourage flowering and fruiting until the plants are well developed and producing flower buds.
How to use peat-free compost: for seeds and cuttings
Feeding plants in containers: fruit, vegetables and ornamental plants
Plants growing in containers need feeding to perform well. The potting compost available in garden centres provides optimum amount of nutrients for about six to eight weeks, but after this you’ll need to start feeding. If you make your own potting compost, the soil and organic matter in the mix should provide enough nutrients in the first growing season, unless you’re growing fruit and veg.
Liquid feed the following with homemade or organic fertilisers during the growing season (April to September). How often depends on the fertiliser you use, but below is an approximate guide.
- Fruit and vegetables every two weeks, or weekly if using homemade feeds
- Bedding plants for summer colour once a week
- Ornamental plants such as trees, shrubs and perennials once a month
- Undemanding plants, such as olives and bay trees, once a month
- Ericaceous (acid-loving) plants, such as blueberries, camellias, azaleas and rhododendrons, once a month with ericaceous fertiliser or seaweed feed containing iron
How can I reduce the need to liquid feed containers?
To minimise liquid feeding, which can be time consuming, mix an organic fertiliser into the potting compost before planting up your pot. Alternatively, you can also scatter it over the surface (known as top dressing). There are some specific organic products designed to add to potting compost . Check label for details of how to apply.
Choose plants for containers, that need only feeding occasionally. These include ornamental grasses, drought tolerant shrubs and Mediterranean herbs.
Drought-resistant plants
Feeding plants growing in the ground: fruit and vegetables
Mulching regularly (at least once every three years) with organic matter can deliver all or most of nutrients fruit and vegetables need to give you plentiful crops. Try the no-dig approach by avoiding soil cultivation and applying 5cm of mulch each year.
You can also use green manures to boost soil fertility by sowing long rooted plants to draw nutrients from deep in the soil and those that fix-nitrogen.
If you garden on free draining sandy or chalky soils, or grow hungry crops such as brassicas, additional fertilisers may be needed. Use homemade or organic fertilisers, such as fish, blood and bone, seaweed or comfrey-based feeds since these reduce environmental impact.
Green manures
No-dig gardening
Feeding houseplants
Houseplants rely on regular feeding for healthy growth. How much feed depends on the type of plant. Most leafy plants enjoy feeding with a liquid general-purpose or houseplant fertiliser once or twice a month from March to October.
Orchids need a specialist liquid feed that’s weaker than others, while cacti and succulents enjoy feeding once a month with tomato feed or specialist cacti fertiliser. Feed these during the main growing season April-September.
Check out our individual growing guides for more details on how to feed different groups of houseplants.
How to grow Phalaenopsis (moth orchids)
How to grow cymbidium orchids
How to grow houseplant cacti and succulents
How to grow houseplants
Feeding sick plants and nutrient deficiencies
It is a common belief that poor growth is caused by a lack of soil nutrients and that applying fertiliser is the solution. The results of our Soil Analysis Service suggest that phosphorus, potassium and magnesium shortages in cultivated soils aren’t common.
Disappointing performance and leaf symptoms are often due to poor establishment after planting or weather related factors. These include roots drying out or becoming waterlogged which limits the uptake of nutrients present in the soil. In this instance, improving the soil and repotting plants in containers can sometimes help.
Some symptoms indicate a lack of nutrients. Certain groups of plants, such as tomatoes, raspberries and ericaceous (needing acid soils), are more prone to this than others. To help you identify when plants aren’t getting enough nutrients see our nutrient deficiencies webpage.
Nutrient deficiencies
Trees and shrubs: establishment problems
Waterlogging and flooding
When and how do I feed plants?
It depends on the type of fertiliser you’re using, as different fertilisers release nutrients at different rates. Time your application for when the plants need it most, normally during the growing season (April to September).
Please see our guidelines below for when to apply:
Mulches
- Apply organic mulch and other soil improvers in spring or autumn-winter
Dry fertilisers
- Before you apply, always check the label and stick to the recommended dose and frequency. Remember, more is not necessarily better.
- Organic fertilisers, such as fish blood and bone, poultry manure pellets, comfrey pellets and seaweed meal, are relatively slow to release their nutrients. These are applied in late winter or early spring in preparation for the growing season.
- Synthetic fertilisers, such as Growmore or ammonium sulphate, applied directly to soil are faster acting than organic alternatives. They can be applied later in early to mid-spring. These often come in pelleted or granular form.
Liquid fertilisers
- Apply these feeds when watering during the main growing season from spring to early autumn (April-Sept). They work well for plants in containers or growbags as liquid feed can be mixed in a watering can.
Fertiliser labels explained
Fertilisers
Seaweed products
Problems
Fertiliser may not be effective if applied to compacted soil. Forking over the area may then be necessary to relieve the compaction and improve fertiliser uptake.
Allowing fertilisers to touch plant leaves can cause leaf scorch. Spread or water fertilisers around the base of the plants that need it. Only fertilisers designed to be applied to leaves, e.g. foliar feeds, should come into contact with them.
Avoid feeding late in the growing season, encouraging new soft growth that will not have time to mature before onset of winter, making it vulnerable to weather damage. Only few plants need fertiliser in the winter months, even if they are winter flowering.
High soil fertiliser levels can inhibit the activity of soil microbes such as mycorrhizal fungi.
Mycorrhizal fungi
Soil: cultivation
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