“The nation that destroys its soil destroys itself” – Franklin D. Roosevelt.
This 2nd blog in our gardening series is your crash course in soil. While we will cover in this series other grow mediums, from hydroponics to clay pebbles, this video is just about soil. There’s a difference between dirt and soil. Dirt tends to be nearly void of organic materials and nutrients. Soil is a living thing, rich in nutrients, and usually always in the process of rendering organic materials into micro and macronutrients. Nutrient-rich soil is rich in humus, resulting from decaying materials such as leaves, twigs, compost, manure, and grass clippings. Plants use these nutrients to grow. In nature, those plants lose leaves or die off, decay into their base nutrients again, and feed the soil. In a container garden, you often don’t have this decay process feeding the soil and keeping it rich and full of nutrients plants love. The first mistake many container gardeners make is to assume that the bags of potting soil they buy at the store is all they will ever need. You still need to feed bagged gardening mixes because, over time, they will pass their nutrients to the plants you will be harvesting, and we will cover this later in this blog.
When starting out from scratch, you have three choices: purchase pre-packaged soil and suffer the expense, use the dirt from your area and amend it, or combine the two. Each of those choices has considerations you must make. Each will still require you to feed your soil. We will address each in this video. If you buy your soil pre-packaged, you must ensure it comes from a reputable source. Big chain stores sometimes have low-quality bulk garden and potting soil. A nursery where you can buy in bulk, preferably one that mixes its own blend, is the best; however, this can be expensive.
You will see a few different kinds. There’s potting soil, and that isn’t actually soil. It’s a combination of usually five different ingredients. There is typically some type of slow-release fertilizer, often in the form of tiny colored beads. Vermiculite is a type of limited-expansion clay. Perlite, which looks like little pieces of polystyrene but is actually made from superheated and “popped” volcanic glass. Either of these two help to keep your soil looser and aerated. Roots need to weave through the soil, and water needs to be able to flow away from the roots. Neither perlite nor vermiculite provides any nutrients to the plants. Peat moss or coconut coir to retain moisture and provide bulk. And, possibly, some type of bark, usually pine. If you buy a potting mix for the purpose of gardening, understand that it will lose nutrients and require fertilization.
Some people purchase a well-packed block of garden soil, make an X slit on the top and plop a vegetable plant right in there. It can be done, and it is a good basic growing medium for your plants. The nutrients the mix comes with are probably just right for one or two plants over one growing season. The densely packed cube makes it more difficult for insects to infest, but it also makes it rather difficult for roots to penetrate. Moisture control is also a problem, as the cube of potting soil will want to expand when wet and won’t wick water away from roots easily. That said, it can be done successfully, and many use this method.
Another thing to know about potting mixes is that they can go bad. If it smells rotten, detrimental bacteria and fungi may be at work in it. We have heard it said that you could spread it out in the sun, which will kill off the bacteria and fungi, but we don’t think this is very effective. The bacteria and fungi will continue to thrive and use up the nutrients in the soil before your plants can. Your store-bought potting soil could also have an insect infestation. Tiny fungus gnats are the most common. The soil is acceptable to use, but this can be a nuisance. The sub-surface larvae can damage roots. Allowing the soil to dry out completely and using a specially designed yellow sticky trap can manage any infestation of these. They are attracted to the color yellow.
The second type of bagged mix is more of a generic garden soil mix. Typically this doesn’t have perlite, fertilizer, or much vermiculite in it. It’s more of a combination of wood materials, peat moss, coconut coir, and sometimes manures. This, too, will require feeding.
If you plan to purchase your soil, remember that healthy soil is the basis of healthy plants. It’s worth paying up. Purchase your soil, if possible, from a non-chain nursery, landscaper, or farm that produces and amends its own soil. You can purchase their soil by the square yard, pick it up, or have it delivered. Simply measure the length and width in feet of all your containers. Multiply your total length by your total width to derive square feet. Multiply square feet by .11111 to get the square yards of soil you will need. Excess can be stored in a dry area in bins, and you will need to top off your containers as the peat moss decays, settling occurs, and the container volume decreases.
If you plan on mixing your own and saving money, purchase the base ingredients: coconut coir or sphagnum peat moss, perlite or vermiculite or fine sand, and standard garden soil. A typical mix will be 1 gallon each of generic garden soil, sphagnum peat moss, or coconut coir, and then enough sand, vermiculite, or perlite to give you a consistency that, when wet loosely stays together without clumping too solidly into a ball or falling entirely apart. If you want to add some organic components to enrich this base soil, like chicken or steer manure or compost, use just a 1/2 gallon to not over-fertilize and burn your plants. These organics break down over time. These base ingredients can likely be purchased at any garden store, nursery, or landscaper. Buying these base ingredients in bulk is much cheaper than buying several bags of soil from your local store.
WHAT HAVE YOU GOT?
If you are like us, though, spending a bunch of money for garden soil isn’t in our budget. Because of this, we mix our own and use the dirt in our area. You introduce several local bugs, grubs, and other critters to your grow space–some beneficial and some not so beneficial, but it’s much more affordable and provides you with a greater understanding of your soil and what is in it. We will show you how to do this here. To start, you need a soil test kit. These are affordable. It will allow me to test my soil to determine nutrient levels and pH. We will cover the nutrients later in this blog, but let’s do a quick test and see what one of my outdoor garden beds has in it right now. We will link to the specific test we use below.
A few years back, we sprang for a massive load of garden soil for some of my beds, specifically from a landscaper and grower. The beds where we put this soil provided me bumper crops, but my initial costs to purchase several cubic yards of soil were high. For our test, we will use a bed that we started with the lousy dirt in my area and have slowly built up over time. That’s closer to what most people will be working with. This bed is a combination of dirt from the hole for the pond we dug out two years ago and has been steadily amended with compost, grass clippings, bone meal, worm casings, blood meal, and liquid fertilizers since then. The soil in my area is desert soil, and it’s not very good for growing much on its own. We have been building it up slowly over time, but this is the first time we have tested this garden area, so we will see how good or bad it is here for my garlic and Egyptian Walking Onions.
pH tests the alkalinity or acidity of the soil. pH affects the bioavailability of nutrients for your plants. Certain plants will favor certain acidic levels- typically between 4.0 and 8.0. Onions, as in this patch, prefer a soil between 6 and 7- garlic a range just .5 wider in either direction. The test kit has a guide for an array of plants, so you know how to adjust your soil from there. It doesn’t have to be perfect, as you can grow a variety of plants in a variety of soils. If you are within the favorable range of the plant you are growing, however, you will have healthier, bigger, and better plants. Not having the correct pH will lead to nutrient deficiency in plants.
To do the pH test, take a soil sample from your area and break it up into finer parts. This pH test is different than the nutrient tests, so you will only need to follow this procedure once. Fill the soil to the soil line on the container. We put the cap on the test pill side to avoid getting dirt or water in the non-testing chamber. You add distilled water when your test chamber has the soil to the fill line. You use distilled water because it will be in a very narrow pH range of 5.5 to 6.9, depending on how long it has been exposed to air. The tests are calibrated to this in their formulas.
With your soil to the soil fill line, add the water using the dropper to the water fill line. Carefully break open the green capsule and drop the powdery contents into the test chamber. Properly affix the lid, shake vigorously, then wait ten minutes. You should then be able to compare the color to the chart on the test container. Record your results. My color isn’t a perfect match for any key colors, but we estimate it to fall between 6.9 and 7.2. That’s higher than we want for my plants in this area, but it’s what we expect from the soil here in Southern California, which runs slightly higher than that. Most soils west of the Mississippi lean toward alkaline, and water in Southern California is definitely alkaline. The general goal is maintaining garden soil close to neutral or slightly acidic. In Southern California, that means adding acidic elements to the soil slowly and in small quantities over time. If you adjust pH at all, you want to do it slowly. The addition of hydrated garden lime or wood ash will reduce acidity. In my case, unique to our environment, we want to add acidifying elements.
To do this, we can use more compost with leaves in it; kitchen composts with citrus in them, compost tea derived from similar composts, or sulfur powder in small amounts, which we can buy in the gardening section of many stores. The other option is to do like my great-grandmother did for her acid-soil-loving Hydrangeas. She poured pickle juice into the soil. The vinegar acidifies the soil. If you are correcting in this way, one cup of apple cider vinegar to a gallon of water applied every month or so to the whole area will slowly correct pH levels. Some people try to acidify their soil with used coffee grounds, but that doesn’t work because the acid in coffee is water-soluble, so the acid is mainly in the coffee. There is a chart that comes with this kit that defines a few of the soil amendments and quantities needed.
The subsequent three tests are the three primary nutrients plants need: Nitrogen, Phosphorous, and Potash- the common name given to a group of minerals and chemicals that contain potassium and have the chemical symbol K. There are about 17 different nutrients your plants need in lesser amounts, but these are the three biggies. For instance, we add calcium when my peppers show thin walls or sun damage, as the plant uses this to strengthen the walls of the peppers. The best way we have found to do this is to bury a calcium tablet vitamin near the plant and water it. Epsom salt, which is magnesium sulfate, helps seeds germinate and makes plants grow bushier. Boron, Chlorine, Zinc, Copper, and the rest of the 17 are all in your soil to some degree, and you rarely need to supplement them. So, it’s a deeper study than what we need to understand our soil. We just need to understand the big three our plants will need the most.
To conduct this test, you will mix 1 cup of soil with 5 cups (or 40 ounces) of distilled water. Shake vigorously and allow it to settle between 30 minutes and a full day. The clearer and the more sediment free your water is when you do this test, the cleaner your colors will be. We will strain off the water for the test from this to ensure we have little to no sediment in my water. My water is still pretty dirty here, so we will take a second measurement later. Fill the containers to the water fill line with the dropper to eliminate any large pieces of sediment. Use only liquid. Add the contents of the appropriately colored capsule. Affix the cap and shake vigorously. Allow the color to form over 10 minutes, then record your results. Repeat this process with all three test containers.
In our case, our nitrogen was depleted to deficient. Our phosphorous was sufficient. My potash was sufficient. Based on these readings and the conditions my particular plants favor, we can decide how and when to fertilize my plants. At this point, we could safely use any well-balanced fertilizer to bring these NPK numbers up, and we will do just that.
FEED THE SOIL/FEED THE PLANTS
Think of soil as the food source for your plants. Over time, the nutrient levels in the soil will drop because the plant has taken up those nutrients in its growing process. Most potting soils are marked with phrases like “Feeds plants for 6 months” and similar. There are still nutrients there, but they are in shorter supply. Because potting soil doesn’t have a steady supply of falling leaves and other organic material, and pill bugs, worms, and other creatures, breaking down this organic matter and converting it to raw nutrients for your plants, your potting soil can get kind of barren over time.
The easiest solution is to purchase some form of pre-mixed fertilizer and follow the instructions on the package regarding dosage, times, and application. Liquid fertilizers are ideal for this purpose. The plants can access the nutrients more easily. Liquid fertilizers are typically composed of liquified kelp, seaweed, fish, liquid bone meal, blood meal, feather meal, rock phosphate, compost tea, or worm castings tea. In a future blog in this series, we will show you how to make your own liquid fertilizers, as they are expensive if you aren’t buying gallons at a time. The drawback of liquid fertilizers is the cost. While we believe the plants take up the nutrients better from liquid fertilizer mixes, even at a low rate of a tablespoon per gallon of water, at $20 per gallon, it can be used up pretty quickly.
Solid fertilizers are another option. These usually come in the form of plant spikes or granules and release over time with each watering. However, the plant cannot access nutrients unless these are dissolved by water. Granules that dissolve in water are an easy, affordable, and better option we have used for years with great success. For our small vegetable garden, we frequently use Miracle-Gro Granules Plant Food. It has an NPK of 18-18-21, so it’s very balanced. To apply it, you simply dissolve it in water and then water your plants. A $12, 2-pound bag will cover 800 square feet so that it will last you an entire growing season. While it states on the label to use it every 7-14 days, we only use it once or twice per month. When applying it, try to water it as close to the base of the plant as possible, as some plants don’t like any type of fertilizer on their leaves. This is the easiest and most straightforward method of feeding your soil and plants. Another kind is hard granules that can be sprinkled on top of the soil, worked in slightly, or watered immediately. These will release nutrients more slowly over time.
The type of fertilizer you use and when you apply it to your plants is a science unto itself. At different phases of your plant’s life cycle, like establishing roots, greening up, flowering, setting fruit, and maturing, your plant relies upon different nutrients. We want to keep this as simple as possible, so with a smaller setup, we can pick a fertilizer with a balanced ratio of N, P, and K. These three letters represent the levels of the micronutrients your plants need. N is nitrogen and is primarily responsible for the growth of leaves on plants. P is phosphorous and is mainly responsible for root growth and flower and fruit development. K is potassium which helps the plant’s overall functions. Different plants favor different ratios at different times. These nutrients will be expressed on the label in three numbers– 2-2-2, 4-5-4, 5-10-5, 8-0-24, or similar. For a contained area small garden like ours, you want something that is pretty balanced and not too extreme, so a 3-3-3, 4-5-4, or 18-18-21 is going to be mild and balanced compared to an extreme 8-0-24. You don’t want to put your soil off balance.
Typical potting soil that is marked that it will feed plants for some period is usually fertilized to an NPK ratio of 3-1-2. That’s ideal for indoor potted plants but will deplete nutrients quickly for vegetable plants with a more rapid growth rate. You can’t simply put your plants in pots and then forget about them when it comes to feeding them. They need nutrients to survive, and the lack of newly introduced organic materials will create a barren environment. While many people’s inclination will be to simply bring in organic material like leaves to mix in their soil, don’t do this if you are container gardening. The risk of introducing insects to your garden is too significant. A tomato hornworm can produce nearly 1400 eggs so small you won’t notice them. A soldier fly will lay 500 eggs that aren’t bigger than a grain of rice. A weevil will lay about 300 eggs, and they’ll hatch in about three days. A mature aphid lays 3 to 6 eggs per day that are only a half millimeter long. One handful of organic material from the wild could introduce thousands of bugs to your growing space. If it isn’t insects you introduce in this manner, you could introduce millions of fungus spores. Some fungus spores will ravage your soil of all nutrients and kill your plants.
The only safe way to do this is to grind up the organic material and then boil it to kill any eggs or let a compost pile heat it up. Only that will kill off insect eggs and fungal spores, but this is a lot of work. Trust us, with small-space gardening, you are far better off with organic pre-made fertilizer mixes than with a handful of leaves. We’ll cover in future blogs organic methods we can deploy, like a worm tower, composted kitchen scraps, and similar techniques, but this will depend significantly on what growing method you use and the space you have available. Again, the safest and easiest way to keep your plants fed and pest free is a pre-formulated, balanced fertilizer.
The final thing to know about those micro-nutrients N, P, and K is that different plants will favor different balances and take what they need and leave what they don’t. If we know we are specifically going to grow something like a pepper, for instance, we simply do a google search for the ideal NPK for pepper plants. You will find pepper plants like a 5-10-10 mix when you do this. Lettuce, on the other hand, likes 8-15-36. Onions like a 20-20-20 ratio. These super-balanced generic fertilizers shoot for the middle range of most plants. If you are growing something very particular, you might want to match your fertilizer or tweak your fertilizer more closely to that plant’s preferred combination. It’s a real rabbit hole you can go down, which all comes with time and understanding your plants’ needs.
Are you feeling overwhelmed? Don’t be. When it comes to soil and fertilization, you want to keep an even balance middle-of-the-road approach until you know what you’re doing. It’s like using salt in cooking. You can’t take the salt out once you have added it to your cooking, so it’s best to err on the side of too little than too much. If you use a balanced fertilizer, you will not likely go too far out of whack for any of your plants. For now, your takeaway is simply that you do have to feed your plants, and you should look to do that with balanced fertilizers marked “All Purpose,” “For Vegetables,” or with relatively even NPK ratings.
THE FINAL SCOOP
There is, of course, a whole lot more that we could put in here. As in-depth as all of that may have seemed to you, there’s so much more to the soil–volumes and volumes of information. There’s enough in the field of soil science that you could get a bachelor’s degree just in that topic. That’s far more than we can cover here, but what we cover here is enough to get you growing and learning as you go. From this, you will be able to understand your pH, the big three nutrient levels-NP & K, the types of soil available to you, and how to calculate how much you will need. Most importantly, you will begin to understand your soil. From that, you will start understanding where and when to adjust it.
One final thing to note is that as our understanding of soil mechanics has increased over the years, so has the complexity of what is available to you. Many soils and fertilizers now advertise that they are inoculated with healthy bacteria and fungi. This fertilizer we are using is an excellent example of this. Neither the bacteria nor the fungi feed the plants. They perform, instead, a host of other environmental controls. They make it more difficult for harmful bacteria and fungi to take hold in your soil. Primarily, they help break down organics and facilitate the transport of micronutrients to your plant’s roots. A mycorrhiza, for instance, is a symbiotic association between a fungus and a plant. Fungi mineralize nutrients from organic matter. Sometimes they feed on each other to produce nutrients. Their workings are far too complex and nuanced to cover here. For our purposes, don’t shy away from ingredients that begin with “bacillus” or end with “mycorrhizae.” These will be naturally occurring beneficial bacteria and fungi that will transform dirt into living soil.
Thanks for growing with us, and stay safe out there.
Soil Test – https://amzn.to/3FxIdeo
Basic Fertilizer – https://amzn.to/3uAv2TX
Yellow Sticky Gnat Traps – https://amzn.to/3FBcolg
Storage Bin – https://amzn.to/3uytOIY
Seeds – https://bit.ly/3PoA0ww
Gardening Guides & Seeds – http://bit.ly/3GkkoqE (family-owned)