Plant foods and fertilisers explained

Just like us, plants and flowers need a balanced diet in order to live healthily. Ensuring that your plants receive the nutrients they need will help to encourage your plants to thrive, producing more flowers and fruit, and lush dense vegetation. Certain plants will require more support than others – container plants have limited access to soil resources so may need a helping hand, and fruits and vegetables will benefit from an extra boost to generate a good harvest.

Composting provides a great way to feed your plants for free, and is an easy way to recycle your kitchen, garden and even office waste.

Plants need to feed on six main food groups. Carbon, Hydrogen and Oxygen are conveniently free to the plant from within their natural surroundings. Nitrogen, Phosphorus and Potassium are less abundant in the natural environment and will need to be topped up. Food and fertilisers contain these vital ingredients together to manage feeding your plants as easily as possible.

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Why not try creating your own plant food? Composting provides a great way to feed your plants for free, and is an easy way to recycling your kitchen, garden and even office waste. Nearly half the contents of an average dustbin could be used to make compost, so you're probably ready to get started!

  • How to compost

    There are no tricks involved or careful planning required, simply designate a corner in the garden for your compost bin and start filling. Time does the rest and with a little patience you should have a rich compost to feed your plants.

    Turning your compost every couple of months will help to speed up the process of decomposition, so that your compost is ready to use sooner. Make sure that compost has a smooth texture with no visible leaves or vegetation. Evenly distribute across the area you wish to fertilise and dig in well with a garden fork.

    A purpose built compost bin will help to keep your garden tidy and make composting easy – try a traditional wooden bin for country garden styling, or an efficient plastic composter for easy use. Rush screening or trellis with climbing plants can help to hide your compost from view.

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  • Compost accelerator

    Can't wait to start using your compost? Speed up your compost making with a Compost Maker. Biological formulations with added microbes and enzymes will help to encourage faster composting. You might also want to avoid certain items in your compost – citrus peelings and banana skins can take longer to break down.

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  • What to compost

    Great compost is made from a variety of composted materials - our table below explains what can be composted at home, and how it will benefit your garden.

      Nutritional Value Notes
    Beverage waste and old kitchen water Neutral Good to add moisture to your pile but try not to use too much or risk creating a swamp!
    Cardboard Carbon Only use in small quantities and ensure it is wet. Consider recycling large quantities.
    Corn cobs or stalks Carbon Best when shredded.
    Coffee grounds and filters Nitrogen Great treat for the worms!
    Fruit and fruit peel Nitrogen Fleshy peel like banana peel can take longer to decompose, bury in the middle.
    Tumble dryer lint Carbon Great for moisture levels.
    Egg shells Calcium Crush shells as they break down slowly. Great obstacle course to keep the slugs and snails away.
    Hair Nitrogen Sprinkle evenly across pile.
    Dry or Green Leaves Carbon Avoid using diseased plants or bushes.
    Manure (chicken, cow, goat, horse, pig, rabbit, sheep) Nitrogen  
    Newspaper Carbon Similar to cardboard, only use in small broken down amounts. Consider recycling large amounts.
    Pine needles and cones Carbon Slow break down and acidic finish, use moderately.
    Sawdust and wood shavings Carbon Very high carbon content so avoid using lots unless you can balance with a lot of nitrogen. Use untreated wood only.
    Vegetables Nitrogen Bury deep to speed up break down.
  • What not to compost

    Whilst it's a good idea to compost as much as possible, try to avoid the following materials which could lower the quality and nutritional content of your compost.

    Ashes from coal or charcoal Acidic finish burns through good nutrients.
    Dairy (cheese, milk, yoghurt) Can attract unwanted pests.
    Diseased plants Avoid composting to reduce disease spread.
    Fish scraps and bones Builds unpleasant smells and attractive to unwanted rodents.
    Lemons and limes Too acidic, may stop composting process.
    Manure (bird, cat, dog) May contain diseased organisms.
    Meat, fat, grease, oil or bones. Lack in any nutritional goodness to plants and do not decompose well.
    Treated wood Too high in alkaline levels which suppresses composting.
    Weeds Can be poisonous.

Understanding fertilisers

  • pH Values

    The pH value of soil determines how acidic or alkaline the environment is. Different plants favour different soil conditions, but most prefer a neutral pH close to pH 6.5. Every garden is unique, but high or low pH's can be balanced by the addition of certain supplements to the soil. These will neutralise the soil, making it more suitable for a wider range of plants.

    Test the pH value of your garden with the B&Q pH and Soil Moisture Tester

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    If the pH is high: You can use aluminium sulphate or sulphur to neutralise.
    If the pH is low: You can use lime or wood ash to neutralise.

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  • What does the N-P-K ratio mean?

    Most general use fertilisers use a ratio of 5-5-5. These numbers refer to N-P-K, the amount in grams of nitrate, phosphate and potash per 100 gram supplied. If you have specialist requirements, look for fertilisers with differing ratios to meet the needs of your plants.

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Choosing the right fertiliser

The easiest way to make sure your plants are receiving the nutrition they need is to select a product designed specifically for them. Universal fertilisers are a great choice for containers and beds which contain a multitude of species, but consider using something tailored to the needs of more specialised plants.

  • Fruits and vegetables

    Bring your home grown fruit and vegetables to life by using a specialist fertiliser. Tomato feeds such as Tomorite contain extra Potassium to help produce a bumper crop, whilst potato plant foods will contain predominantly Potassium and Nitrogen. Universal fruit and vegetable foods can be a great help for gardeners growing a range of crops as these make it possible to feed a whole vegetable bed or multiple containers with the same feed. Choose organic fertilisers and plant feeds where possible to encourage sustainable growing.

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  • Shrubs and trees

    Use a specialist feed to protect your shrubs and trees year round to ensure a full blossom in Spring and then ripe delicious fruit later on in the season.

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  • Specialist plant foods

    Ericaceous plants such as Azaleas, Heathers, and Rhododendrons require quite different N-P-K levels in the feed and fertilisers. These species prefer acidic conditions and flourish on a combination of a wider range of nutrients. Roses and many houseplants will also benefit from specialist formulations.

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Top tips

Most plant foods and fertilisers are easy to use – simply follow the instructions on the packaging. Here are a few top tips that will help you to get the best results when using plant foods;

  • Follow the instructions given on the packaging carefully – take care to follow any safety precautions, and use at the specified time of year to achieve the best results.
  • Don’t underestimate the importance of keeping your plants well watered.  No plant food or fertiliser will be able to mend the damage that dehydration can do.  Water early in the morning or late in the evening to ensure plants can absorb as much as possible before it evaporates.
  • Consider using a continuous release plant food if you’re not able to tend to your plants regularly.  This will provide sufficient nutrients for the whole growing season in one application.
  • Apply liquid feeds at the base of the plant to help the root system absorb as much of the food as possible.
  • Use a liquid feed for hard to reach areas, such as hanging baskets.  It will be easier to reach the roots of the plant using a watering can or sprayer.
  • Don’t forget houseplants!  A wide range of products will help indoor plants stay in good health.  Consider a liquid feed for larger containers, or a drip feeder for easy maintenance.
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