Types of Fertilizers
Fertilizers come in pellets, sprays, spikes, and just about any form you can think of. Some are organic, some are synthetic, some are plant specific and some are all purpose. Here are some common types of or terms used to describe fertilizers.
- A balanced fertilizer has equal parts of each, 10-10-10, for example, has 10 percent by weight or volume of each nutrient. The rest of the fertilizer percentage is filler.
- Organic fertilizers have very low numbers 4-4-4 or such. They are derived from naturally occurring materials and are not synthetically made.
- Plant specific fertilizers, like rose fertilizers are designed to provide the macro and micronutrients that plant needs.
- Slow release fertilizers are mixed into the soil or soilless media and provide nutrients over time as the pellets break down.
- A complete fertilizer has all three components NPK. An incomplete will have a zero for the missing element.
- An all-purpose fertilizer is a complete fertilizer and contains other nutrients.
Rate of Application
Often, the rate of application (how much fertilizer to apply per square foot) isn’t given on the container and it can be hard to know how much to apply. I water my plants with the same amount of water as I would with plain water when applying fertilizer mixed in my watering can. Water once a week for annuals and vegetables. Perennials don’t need to be fertilized as often, unless they are heavy feeders, like roses.
Organic Fertilizers
There are many different organic fertilizers, such as fish emulsions, compost teas, compost, and various types of manure. You can make your own or buy them. A drawback of homemade fertilizers or mixes is that you can’t tell what levels of nitrogen, phosphorus, and potassium are present and you risk over or under fertilizing.
Watch for signs of too high of a nitrogen content, such as too much lush green growth or leaf burn on your plants, especially if you are using manure. You can purchase organic fertilizers. They (usually) give the primary macronutrient ratio, plus often other levels of secondary or micronutrients. I would be hesitant to use a product that doesn’t list the fertilizer ratio or its nutrient content.
Synthetic Fertilizers
These are the popular, brand name, man-made fertilizers, such as Miracle-Gro. Unless fertilizers are labeled organic, consider them synthetic. The advantage of synthetic fertilizers is that they contain higher concentrations of the macronutrients than organic and produce bigger, faster results. Synthetic fertilizers are easy to use. They come with a scoop or pre-measured bags you can add to a sprayer. They dissolve rapidly in water. Basically, they are simple to use and produce results.
Just as it’s easier to under-fertilize with organic fertilizers, it’s easier to overfertilize with synthetic fertilizers because of their higher concentrations. Most fertilizers are salts, so not only will you risk providing too much of a nutrient, you also risk damaging your soil by increasing its salinity. To prevent this, make sure you mix and apply them according to the label’s instructions.
Controversy Over Organic vs. Synthetic Fertilizers
Remember that all fertilizers are chemical, even organic. That doesn’t mean bad, it means that is what the components are made up of – NPK are all elements on the periodic table. Our entire world is made up of chemicals. What does matter most is that you aren’t introducing anything toxic or in too great a quantity.
Organic fertilizer is derived from natural sources. Synthetic fertilizer is a copy of those. Plants can’t tell the difference between an organic or a synthetic nutrient. Organic fertilizers often have an enhancing effect on the soil by introducing or nurturing soil microbes. They also are in smaller concentrations so there is less chance of over doing it with them.
How likely you are to use them depends on your preference for the ‘all natural, organic’ vs. ‘I want super blooms all summer’, mindset. Gardening shouldn’t include a guilt trip, just know what you are applying and only apply it in the needed amounts. Check out this post on the Five Steps of Integrated Pest Management for some guidance on how to best care for your garden without harming the environment.
Check out a custom curated list of fertilizers here:
Fertilizer
Summary
Understanding plant fertilizer means knowing your plant’s needs and knowing your soil’s fertility and pH. Amend with organic matter, such as compost, to maintain your soil’s health, and fertilize at the right time with the right blend of fertilizer. Watch for symptoms of deficiency and act quickly to remedy them.
