Some plants thrive on neglect, needing just a little bit of light and maybe a dash or two of water every now and then. But if you want to see your plants — everything from herbs to veggies to houseplants — really flourish, then you’ll want to add plant fertilizer to your routine.
Plant food plays an essential role in prepping your garden beds for winter or gearing up for spring planting. Of course, fertilizing your garden is a good move, but those made from synthetic chemicals have many adverse side effects. Fortunately, many common household materials are also helpful as organic fertilizer.
Organic gardening is a good move. And if fertilizers are ever in short supply or outrageously priced, you’ll have some readily available options from around the house you can use instead.
Why is fertilizer necessary?
Dead soil equals dead plants.
On the other hand, living soil is full of nutrients and organisms integral to garden health.
Plants need certain nutrients to live and grow. To get these nutrients, they take them out of the soil. As a result, nutrients in the soil are depleted and must be replaced somehow.
Companion planting and crop rotation are two ways to replenish nutrient-depleted soil. Fertilizer is another.
What nutrients are needed in the soil for plant growth?
There are three main groups of nutrients that healthy garden plants need in the soil:
- Primary nutrients (which plants need in large quantities): Nitrogen (N), Phosphorous (P), and Potassium (K).
- Secondary nutrients (which plants need in smaller quantities): Calcium (Ca), Magnesium (Mg), and Sulfur (S).
- Micronutrients (which plants only need in trace amounts): Zinc (Zn), Iron (Fe), Boron (B), Manganese (Mn), Chlorine (Cl), and Molybdenum (Mo).
If a plant doesn’t receive these nutrients in the amounts they need, it won’t reach its full potential and may even die. So for your garden plants to be their best, a steady supply of plant food is a must.
What nutrients does MY soil need?
To know what your soil needs, you must test it. Otherwise, it’s just a guessing game that will likely result in money wasted on unnecessary fertilizers and plants that don’t develop to their potential.
The results tell you what nutrients your soil lacks. This information, combined with what you want to plant, provides direction on the amount and type of fertilizer needed.
However, if the fertilizer you choose is potentially harming soil microorganisms while it’s replacing nutrients, well, you can see the problem.
What’s the difference between synthetic/chemical and organic fertilizers?
Short answer: Chemical and synthetic fertilizers feed the plant. Organic fertilizers feed the soil.
The advantages and disadvantages of synthetic/chemical fertilizers
Synthetic/chemical fertilizers are the fast food of the plant world. They’re designed to address the nutritional needs of the plant. The nutrients they put back into the soil are highly absorbable and contain specific nutrients in specific quantities.
However, they also have a lot of negative side effects.
For instance, they mess with the soil ecosystem; they’re typically quite acidic and hostile to beneficial microbes and other organisms. In addition, they’re harmful to people and pets, and they’re damaging to the environment.
As if that wasn’t enough, because they feed the plant, not the soil, they must be reapplied during the growing season unless using a time-released variety.
The advantages and disadvantages of organic fertilizers
On the other hand, organic fertilizers are part of the slow food movement. They have soil health uppermost in their minds, releasing nutrients over a more extended time. All those wonderful microbes and organisms we want living in our soil are more likely to thrive from a steady supply rather than bingeing. Soil structure and water retention can improve also.
It’s a matter of opinion whether the downsides to organic fertilizers are indeed disadvantages or just inconveniences.
For example, choosing organic is not a quick fix. It means you’re in it for the long haul. Some nutrients must be converted into a usable form for plants by those soil microbes. Concentrations are unlikely to be as high, and composition won’t be as precise as synthetic/chemical.
But like I said, these are only disadvantages if you’re looking for immediate results.
What materials can be used as organic fertilizer?
Here are some common materials that can make a great organic fertilizer. Some provide a very balanced mix of nutrients, and others will give you a few specific nutrients to target a deficiency. But, again, soil testing provides direction on your soil’s specific needs.
- Material from compost supplies your garden with a very good mix of the nutrients it needs. It’s the single best thing you can do for your garden. For best results, make sure you add both green materials (things like kitchen scraps, which are high in nitrogen) and brown material (things like dried leaves and shredded cardboard, which are high in carbon).
- Worm composting is a cool variation on the traditional compost heap. Adding certain worms to your compost helps break down the organic material faster. A regular compost heap might take months, but a worm composter takes mere weeks.
- Chicken droppings don’t have to be just a smelly mess. Droppings can be an effective, reasonably balanced organic fertilizer for your garden. Don’t let this valuable resource go to waste if you have chickens as pets!
- Coffee grounds sprinkled onto your soil supply nitrogen, potassium, and magnesium. Dry them first. Remember, though, that it could alter the pH of your soil. Ask for free coffee grounds at Starbucks or other coffee shops.
- Ash from your fireplace dusted on soil contributes potassium and calcium carbonate. This, too, could change the pH of your soil.
- Epsom salt supplies magnesium and sulfate to the soil. This is especially important with tomatoes, potatoes, and roses.
- Powdered eggshells sprinkled onto your soil increase calcium carbonate (also known as “lime”). You can find eggshells that can be shipped to your door here.
- Mix seaweed and water and let it sit for a few months to create a fertilizer high in potassium. You can also get some seaweed that is ready for your garden now.
- Pine needles supply nitrogen. They also could alter the pH of the soil.
Why is soil pH important?
The pH of your garden soil determines the availability of nutrients for plants. If the soil pH is off, plants may show a deficiency in a nutrient even if that nutrient is in the soil. This is because the plant can’t access it because of the pH.
Whether a fertilizer raises or lowers soil pH depends on the soil’s original condition. For example, an item with a pH close to neutral, like used coffee grounds, will increase the pH of alkaline soil but decrease the pH of acidic soil.
Remember that soil testing kit I mentioned earlier? It’s your friend.
A Cheaper, Easier, Healthier Option
Using these everyday items as plant food for your soil is a cheap and easy alternative to synthetic chemical versions. In addition, choosing organic fertilizer is a small way to help to make the world a healthier place.
However, fertilizing is just one piece of the gardening puzzle. To learn what all the pieces are and how they combine to help you prepare for and create your best garden yet, take my gardening self-assessment.
What kind of organic fertilizer do you prefer?
This article was originally published on 5/14/2019 and has been updated.