Plants need nutrients, air, sunlight and water to grow. A plant positioned in a good location and regularly watered will do well, but of you want to make sure they thrive and become truly beautiful plant then you need to supplement this with a good feeding regime.
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Vital nutrients for plant growth
The basic elements of a plant's diet are nitrogen, phosphorus and potassium (collectively known by their chemical symbols - NPK). These are all present to a greater or lesser extent in ordinary garden soil. Nitrogen encourages leaves to grow, phosphorous promotes root growth, while potassium is essential for producing flowers and fruits.
All plants need these nutrients in varying amounts, but each will only take in the amount they require (as long as it's available). By topping up the supply of essential nutrients in the soil regularly, you'll enable your plants to absorb the right amounts while promoting strong, healthy growth and plentiful flowers and fruits.
Plants also need smaller amounts of minerals such as calcium, sulphur, iron, magnesium, copper and zinc. There are usually enough minerals like magnesium and iron in the soil for most plants - but there are some exceptions. Tomatoes often suffer from a lack of magnesium, while acid-loving plants may not have enough iron if you plant them in an alkaline soil.
Plant food or fertiliser is any substance added to the soil to enrich it with essential nutrients. There are lots of different fertilisers on the market, but they all contain varying amounts of the essential elements nitrogen, phosphorus and potassium. There two main types of fertilisers: liquid and solid.
Keep all fertilisers and chemicals out of reach of children and pets, and never store them in unmarked containers.
Liquid fertilisers come as a concentrate that you dilute in water or as a powder which you dissolve in water. A liquid fertiliser only takes a few days to work, because plants absorb their nutrients in liquid form. It gives actively growing plants a quick boost, but you need to apply it regularly as it doesn't stay in the soil for very long.
You can get solid fertilisers in granular or pelleted form. They give you better growth as they release nutrients more slowly and so stay effective for longer. As a result, you usually only need to apply them once or twice in a season.
When to apply fertiliser
General purpose granular fertiliser works best when the soil is moist. Try to apply it in the Spring, at the start of the growing season. You can also give your vegetables a boost in summer by digging it into the soil around the plants.
It's advisable not to use granular fertilisers (particularly the ones that are high in nitrogen) after mid-summer because nitrogen promotes leaf growth and a fresh flush of growth in late summer might be damaged by early frosts. You should work other types of fertiliser (like bone meal, which encourages root growth) into the soil when you're planting in Spring or Autumn. Alternatively, you can use liquid fertilisers at these times to boost your flowering plants, fruit and vegetables.
Green manures are crops that are dug straight back into the soil to enrich it. Usually from the legume family (especially bean or pea plants), they can 'fix' nitrogen in the soil. Many plants used as green manures store nitrogen in nodules on their roots and this is released back into the soil when they decompose.
Most plants shouldn't be used as green manure; grass clippings and weeds need lots of nitrogen to help them rot down - which means they actually extract it from the soil if they're dug in.
Feeding your outdoor plants
Keeping your outdoor plants well fed will help them to be strong and withstand weeds, pests and diseases. They'll also produce more flowers for longer, while fruit and vegetable plants will give a higher yield of better quality. To get the best results, try to feed each plant with the nutrients it needs - when it needs them.
Use a straight fertiliser to target specific nutrient deficiencies, such as a lack of magnesium in tomatoes.
Always use a rose-specific fertiliser to keep your plants strong, healthy and better able to cope with pests and diseases.
Most bulbs pop up year after year and the bulb itself acts as an energy store to support the next year's flowers. Feeding the bulb straight after it flowers and before it's leaves die back will help ensure a bumper show of flowers the following year.
Plants in hanging baskets and containers
As well as watering your hanging baskets and containers every day, it's very important to feed them regularly. Most only contain a small amount of compost compared with the amount of plant growth they support and nutrients will quickly become depleted. Slow-release fertilisers in granular, stick or nugget form are all fantastic for long term planting, while regular liquid feeding gives the best results for seasonal bedding plants.
Use a specific tomato plant feed when the first fruits have formed.
Fertiliser is vital for keeping your lawn lush and green. It's best to feed it in Spring and Autumn when the soil is moist. The first of these feeds should be high in nitrogen to kick-start the growth of lush new grass, while the Autumn feed should be high in phosphorous and potassium to toughen the grass up for the winter. Many lawn feed products combine lawn fertiliser with weed killer. You apply them in exactly the same way, and the advantage is that well-fed grass will grow more vigorously to fill any gaps where the weeds have died back.
Feeding your indoor plants
It doesn't take a vast reserve of skill or knowledge to make your house plants thrive - just a grasp of a few basic principles.
House plants need a specially formulated house plant fertiliser, either as a liquid or slow release solid pellet or stick inserted into the potting compost. You should start liquid feeding in the Spring and continue it through the Summer months before stopping in Autumn to allow for the plant's natural slowdown in growth over the Winter.
Many plant species are grown as house plants and these need different types of food to thrive. Choose a fertiliser that's specifically formulated for the type of plant you're growing. This ensures your plant gets the right balance of nutrients to thrive. You can get different fertilisers for flowering and foliage house plants, and specialist fertilisers for orchids, cacti and bonsai.
As plants grown in a conservatory tend to prefer a warm, humid atmosphere, they'll need regular watering. And because potting compost quickly loses its nutrients, you should feed them regularly too. Liquid feed will give them a quick boost, but you'll need to apply it throughout the growing season. An easier option is to use slow-release fertiliser sticks. Always use a purpose-made fertiliser rather than one that's for general garden use. You can get special formulas with a high nitrogen content for your foliage plants.