Simple Approaches to Making and Using Foliar Fertilizers

One of our main goals in the permaculture garden is to foster soil life, and there are many methods we use for accomplishing this goal. We apply thick mulches and add plenty of organic matter. We practice no-dig methods so as not to harm existing soil life, and we enhance richness by adding things like worm compost, manure, and leaf mold. We increase fertility with nitrogen-fixing plants. We cultivate perennial polyculture gardens, as well as use crop rotations in annual beds. From day one on the site, we begin our work as ambassadors of the soil.

But, creating the kind of dynamic and regenerative soil we are after takes time. Two months of work, or even two years, likely won’t get our garden soil to the place we want it.

Obviously, we still want to produce some food in the meantime, and homespun liquid, foliar fertilizers are a great option for doing so. These are particularly effective before soils have reached their optimal fertility because, rather than slow-feeding roots, liquid fertilizers are more commonly absorbed via leaves, the foliage. This isn’t to say we stop caring for the soil, as has happened with other fertilize-based agriculture, but we can use simple DIY liquid fertilizers to boost production as we work the soil back into shape or when it seems plants are lacking something.

The other thing to keep in mind here is that we’ll be making our own, organic sprays, so they won’t be wash away like the chemical sprays that have given foliar fertilizers a bad name. Water solubility is both why chemical fertilizers wash away and why they end up corrupting our fresh water sources. Because our sprays are made with organic materials, they slowly release nutrients in the ground, and rather than sloshing down the hill in the next rain, organic liquid fertilizers will remain in the soil, further enhancing it.

A Few Good Recipes

Vermicompost (Courtesy of Engineering for Change)

Just as there are dozens of ways to make a good compost, there are many routes to creating a good foliar fertilizer. While NPK-heavy (nitrogen, phosphorus, potassium) fertilizers are the standard, quality liquid fertilizers—like a truly fertile soil—will contain much more than that, including plenty of trace minerals and micronutrients. In other words, we want our plants to be balanced and healthy, not just large, and that requires using diverse, natural elements with plenty of life to them. In reality, a good foliar spray, just like a good soil-building regime, will likely mix many different elements. But, first things first, let’s get the easy version of some simple sprays.

Compost tea ought to not be to revolutionary to most permaculture folks, even newbies, and that’s because it is undoubtedly a good choice that most of us can create without any outsourced inputs. The key to good compost tea is using only really mature compost, thus avoiding any issues with pathogens. While advanced methods involv pumps and constantly oxygenating the solution, we are working to keep things simple here. Use a good-sized bucket (five-gallon is great), fill it about a third of the way with compost, and top it off with untreated water. This should be stirred a few times a day for three days, after which time the compost can be strained away a tossed on the garden soil. The tea should be diluted (1:10) with water.

Worm juice is really similar to compost tea but uses vermicompost process to harvest the bio-rich, liquid fertility. Most worm composting systems are built with some sort of collection method that harvests the “juices” from the worms’ bodily functions. This can be diluted about the same as compost tea. If the worm bin doesn’t have a juice harvesting mechanism, vermicompost tea can be another option. Some people just stick a scoop of vermicompost into a fine mesh bag, tie it shut, and let it steep in a watering can overnight.

Obviously, well-rotted manure from other animals can be used the same way to blend a manure tea. It’s a great method of stretching the resource for those who don’t have a huge supply readily available to them.

Green tea is another simple way of making the most of what’s around. While green material is not always the best idea for mulch (it tends to form slimy spots), freshly cut grass can be used to make tea. The same goes for weeds. Some people really fret about adding weeds back to the garden, so using them in a liquid fertilizer is a great way to get some immediate nutrients out of them before tossing them in the compost. Comfrey and nettles are particular good for liquid fertilizer. This time, the bucket should be filled about two-thirds of the way with fresh green material and topped up with water. It should be steeped, stirred, and strained like the compost tea.

Banana tea is created by adding an organic banana peels to our bucket and soaking and stirring it for three days. Because tea from fresh green material has a lot of nitrogen and phosphorus, adding an organic banana peel tea into this mixture could supply the missing potassium of NPK to provide the big three nutrients, as well as a host of other trace minerals coming from the greens and the banana.

Pond water is another good, rich source of liquid that’ll benefit the garden. If there is a spot where fish and/or ducks are being raised, it’s definitely a good idea to tap into the source of fertility for the garden, and it would be wise to consider creating some sort of cycle for cleaning the pond and fertilizing the garden with the nutrient-rich water. The same can be said for aquariums. They are cleaned regularly, and that water—assuming it doesn’t have any chemicals added—makes a great foliar spray. Generally, there is no need to dilute these liquid fertilizers.

Seaweed solution also makes a fantastic foliar spray, and it is particularly a good source of trace minerals that might not be in the soil. Seaweed is readily available at garden centers and the like, or it can be responsibly harvested for coastlines and rinsed of salt. This time fill the five gallon bucket all the way with seaweed, add water, and let it steep for a couple of weeks. The seaweed can then be added to the garden as mulch, and the solution can be diluted as before (1:10) and sprayed on the plants’ leaves.

Diluted urine is another possibility. No steeping is required, but the pee should definitely be diluted, probably to around one-part urine for twenty-parts water. Unlike human waste from elsewhere, urine is not a pathogen problem; however, it should be used on the same day. Urine is super stacked with nitrogen, so that’s worth being aware of, as is the fact that pharmaceuticals may make it through the system and ruin a perfectly good pee spray with chemicals.

Applying Foliar Sprays

Seedlings (Courtesy of Kevin Doncaster)

Foliar sprays work really well for specific applications. They bolster leaf crops, our lettuces and cabbages, as well as vining crops—cucumbers, melons, squashes—and long-season fruit crops, such as tomatoes. They are commonly used on grape vines and annual grains. They are also absorbed very quickly and easily by plants, which means changes can sometimes be detected even on the same day. This really helps with young plants or old crops. What’s more is that, if we mix some of the above recipes, we are creating a really multifaceted fertilizer, filling all sorts of nutrient niches: It’s not just NPK, it’s not just minerals, but it’s cocktail of many things. This is especially useful with container plants or soil-less mediums. Additionally, they are good for cold weather crops because soil nutrients can sometimes get locked up when the ground is below certain temperatures, so it can help us extend the spring and autumn seasons.

That said, foliar sprays have a shelf-life, and in reality, the mixes above should be applied sooner—like, immediately—rather than later. We want to avoid the concoctions fermenting as that will change the pH balance and effectiveness. They also don’t have the long-lasting effect that healthy, fertile soil does. To rely solely on foliar sprays for plant nutrients would require regular application, which isn’t ideal, as well as leave our soils anemic, which is the antithesis of what we want. They are a great way for starting young or transplanted crops off with a bang, for helping when our soils are lacking, and for extending a productive plants output a little further, but the soil is what will provide the consistent nutrients needed. We’re just making the most of our onsite, natural resources here.

Feature Photo: Wet Leaves (Courtesy of Michele Dorsey Walfred)

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