Nitrogen
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- What does it do?
- Nitrogen promotes healthy green leaf growth
- What should I use it on?
- Great for green vegetables, cabbage, spinach etc and makes your lawn sparkle!
- How do I know if I need it?
- Nitrogen deficiency is characterised by spindly yellow leaves
- Examples
- Sulphate of Ammonia
- Organic options
- Poultry Manure is rich in Nitrogen
Phosphorus
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- What does it do?
- Phosphorus helps root development.
- What should I use it on?
- Essentially all plants have roots so all plants could benefit from a bit of Phosphorus.
However, it is rare for soil to be phosphorus deficient, but it is worth checking after a particually persistant rainy spell or if you have a heavy clay soil.
- How do I know if I need it?
- Using a soil test kit is the only sure way of knowing.
- Examples
- Anything with the word 'bone' in it.
- Organic options
- Bonemeal is usually organic but check the label.
Urine definitely is.
Potassium
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- What does it do?
- Potassium (or 'Potash') promotes colourful flowers and tasty rich fruit.
- What should I use it on?
- Hanging Baskets, fruits (tomatoes etc) and houseplants.
- How do I know if I need it?
- Leaves will show first signs of potash deficiency, turning yellowish and browning at the edges. Fruit and flowers will be small and pale.
- Examples
- Tomato feeds and Sulphate of Potash
- Organic options
- Composting the leaves of comfrey or the ash from a woodburning stove or open fire.