Ok, so you’ve been gardening awhile and had some success. Now you’re ready to take your homegrown vegetables or your flower garden to the next level to get bigger plants and bigger yields. Fertilizer is the way to do that. But, there are so many out there, how do I know which fertilizer is right for my plant? And can I make my own? What IS the deal with fertilizer?
To understand fertilizer, we must understand just a little bit about plant nutrition. Just like human beings, plants need a variety of nutrients to perform well and stay healthy. After sunshine and water, of course. The most important three nutrients for plants are nitrogen, phosphorus, and potassium.
When you purchase packaged fertilizers at the nursery, you’ll notice three numbers on all brands. This is the guaranteed analysis, or NPK number. You guessed it…. NPK are the periodic element abbreviation names for nitrogen, phosphorus and potassium. These are the three critical nutritional components for all growing things.
Each of these has a role to play in establishing and developing your plants into strong performers.
Nitrogen
Nitrogen is the macronutrient which helps plants generate lots of green – leaves and branches. It is obviously important for lawns and hedge plants like boxwood. But it is also critical for all plants to be able to generate the most basic of all plant nutritional needs…. chlorophyll though photosynthesis.
Nitrogen is released by “green” plant material in the compost. Green plant material includes grass clippings, chicken manure and vegetable scraps. Nitrogen is sometimes applied in higher concentrations than the other two macronutrient fertilizers. This is because even when added at the beginning of the growing season, it leaches more quickly from soil than phosphorus or potassium.
Phosphorus
The middle number in the NPK formula on fertilizers is phosphorus. Phosphorus is the macronutrient which promotes flowers to bloom. This is not only important for a flower garden, but critical in fruit and vegetable production too. If there is no flower on your tomato plant, there will be no tomatoes! Phosphorus is so important to blooming, that commercial fertilizers with higher concentrations of this element are often called “SuperBloom” mixes.
Also, phosphorus helps roots and stems grow much stronger for an overall much healthier plant. This is especially important for fast growing vegetables and annuals.
Phosphorus is a common soil additive for vegetable gardens because it is the key to large vegetable yields, especially with newer soil. In your compost pile, composted materials tend to have ample phosphorus concentrations.
Potassium
Potassium is the last number on fertilizer packages, and is another critical element for plants at the cellular level. It is the macronutrient which regulates water and allows the plant to absorb water. It is even known to improve drought resistance in plants. Potassium also provides energy for the plant tissues. It is a critical component in chemical processes within the plant tissues.
In the compost, potassium is found in high concentrations from banana peels (no, that is not a wives tale), cucumber peels, coffee grounds and fruit. This is why many gardeners call for side-dressing plants with with your coffee grounds and banana peels.
Now that you know the elements of fertilizer, it is important to note that different plants need different things – and sometimes at different times. Therefore you may want to add more phosphorus during blooming season, more nitrogen for younger plants, and so on.
If you are planting tomatoes, or other vegetables, read about my suggestions for how to boost tomato nutrition for super healthy tomatoes. I’ve taken all of these principles with a number of years of trial and error to come up with a great organic recipe for what to put in the planting hole. You can also read a little bit more about pepper nutrition here. Also check out this article on the best natural, organic and balanced fertilizer I have found – Rabbit Poop!!
One last note about fertilizers. Many websites claim that Epsom salt (magnesium sulfate) is good to enhance bloom on tomatoes or to correct a magnesium deficiency. Some even claim that it prevents blossom end-rot. Epsom salts do appear to promote blooms and are also used by commercial growers to correct magnesium deficiencies in soil.
However, and unfortunately, magnesium sulfate interferes with a tomato plant’s ability to absorb calcium. Tomato plants need extra calcium to prevent blossom end rot. Therefore, applying magnesium sulfate actually promotes blossom end-rot on your tomatoes and shouldn’t be used unless a soil test has indicated a magnesium deficiency. Stick with fish meal to provide the needed phosphorus for blossom production. This will also give you much larger fruit too. Keep the Epsom salt away from your tomatoes.
