The Dirt on Dirt: Sand, Silt, Clay, and Loam

Photo courtesy of

Photo courtesy of

One of earth’s most vital and under-appreciated resources is sitting beneath your feet right now…dirt! Dirt is actually an amazing substance if you think about it. Millions of years in the making, it gives rise to most plants and by extension most animals, and it is 100% necessary for life as we know it. Soil sustains our ecosystems, grows our food, is integral in the production of the very oxygen we breathe, and yet it gets no respect. Kicked by baseball players, methodically cleansed from our homes, clothing, and hands- we have clearly lost touch with dirt. Dirt is much more complex than you may have been led to believe. Soil is the amalgamation of rocks, minerals, and organic matter, acted upon by the forces of gravity, geologic pressure, weather, and time. So let’s take a minute to learn more about the soil living beneath our feet and give dirt its minute in the sun!

Soil is made up of many small particles. The size and relative ratio of these particles are known as your soil’s texture. There are three general categories of particle size when discussing soil: sand, silt, and clay. Sand particle sizes range from 2.0 to 0.05 mm, silt particle sizes range from 0.05 mm to 0.002 mm, and clay particle sizes are any particle smaller than 0.002 mm. The composition of most soils is usually a mixture of sand, silt, and clay. The ratio of these particles in your soil will have a profound effect on how your plants grow. Finer soils tend to have a greater ability to store soil minerals but also leach those minerals at a faster rate. An ideal garden soil has a mixture of all three particle sizes and is referred to as a loam. This soil (loam) has the best ability to absorb moisture, allow for proper drainage, and transport air; and due to its high content of organic matter, it provides a lasting source of nutrition. Conversely the most difficult soil type to work with is a compacted soil high in clay. It prohibits root growth, struggles to absorb moisture, and doesn’t allow enough air to the roots.

Soil Triangle

Soil Triangle

If you have difficulty growing plants in your native soil or are curious to see what type of soil you have at your home or farm, consider getting it tested at a professional laboratory or agricultural extension. You can also try performing this simple test at home; although not as good as a professional test, it will provide you with a general idea of your soil texture.

All it takes is a clean, empty jar with a lid, some clean water, a tablespoon of detergent and a sample of the soil you want to test. To do so:

  1. Fill the jar about 1/3 full with the soil to be tested.
  2. Fill the jar with water and detergent then cap it.
  3. Shake the jar vigorously and set aside for several hours or overnight.

How to determine your results:

  • If the water is clear and the soil has settled to the bottom; you have predominantly sand soil.
  • If the water is still a little murky with bits of matter suspended in it; you have loam soil.
  • If the water is still murky and there is a visible ring of sediment around the jar; then your soil is mostly clay.
Soil Type Jar Test

Soil Type Jar Test

If you find you are blessed with a rich, nutritious, well-draining, loamy soil, then count your blessings. However, if you are not as fortunate and find that you have sandy soil, the best amendments are ones that increase the ability of the sandy soil to retain water and increase its nutritional content. Amending sandy soil with well rotted manure or compost (including grass clippings, humus and leaf mold) will help to improve the soil the fastest. You can also add vermiculite or peat as sandy soil amendments, but these amendments will only add to the soil’s ability to hold on to water and will not add much nutrient value. If you have clay soil, then it is most important to add organic matter (including grass clippings, humus and leaf mold), but also adding sharp sand followed by either aerating or turning your soil will help improve the compactness of clays. Lastly, adding a healthy layer of wood chip mulch each year will help improve the soil as it decays. Clay soil is not one that can be fixed immediately, but with a little diligence and a few years (and lots of compost), you too will have great soil.

Square Foot Gardening: A Garden for Everyone!

A Square Foot Garden

Gardening is one of those things I believe everyone can do. It is a great feeling to see a child watch a plant grow, and then see the light in their eyes when they pull their first carrot from the ground. The gardening strategy we are about to examine is truly for everyone. I hear from lots of people that they don’t have the space for a garden, or “good” soil, or the time to tend & weed a garden. Well guess what? It does not take a lot of space, time, or soil to grow a garden.

Square foot gardening is a style of gardening popularized by Mel Bartholomew in a 1981 in his book(s) and PBS television series. Square foot gardening is the practice of planning and creating small but heavily planted gardens utilizing one square foot per plant selection. The practice combines concepts from other organic gardening methods including a strong focus on compost, densely planted raised beds, and soil stewardship. Proponents claim that the method is particularly well-suited for areas with poor soil, beginner gardeners, or those with disabilities.

Basically square foot gardening boils down to a few basic concepts:

  1. Gardens are designed in raised bed style.
  2. The soil filling the raised beds is rich and full of biologically active compost and has excellent drainage.
  3. All plantings are given 1 square foot per plant selection.

When planning your garden either a 3’ x 3’ or a 4’ x 4’ raised bed will be the easiest to maintain because you will have access to all plants without walking in the garden bed. Walking in the raised beds compacts the soil which is detrimental to your plants. If you desire a larger garden, consider several raised beds designed in an appealing pattern or layout that fit your space. I would recommend that you always keep 3’ walkways between garden beds, making weeding and maintenance easier. Also pay attention to the orientation (north-south or east-west) of your garden bed when making plant selections (you don’t want to plant corn where it will shade all of the other plants). A few other tips for making your raised bed garden:

  1. Plan your garden on paper to maximize your productivity, minimize your work, and make the most attractive use of your space.
  2. Successive planting is a great strategy to increase your gardening season; after a cool season spring crop like lettuce or radishes is harvested replant the space with beets, beans, or turnips for the summer. Then in the fall replant again with a cool season crop.
  3. Utilize your vertical space with trellises, fencing, or cages to allow climbing or tall growing plants to occupy space without encroaching on neighboring plantings.

My favorite adaptation of square foot gardening is using the principles for an indoor garden. A grow tent is the perfect place to utilize these concepts. You get to grow a variety of plants in a small space, without any weeding or having to contend with the elements, bugs, or disease. By growing in an indoor climate-controlled space, you can minimize labor and maximize yield. Just buy a tent, a soft fabric pot or raised bed kit, build a liner (to protect the floor from water damage,) add some rich organic soil and some seeds and you are on your way. For the do-it-yourselfers out there, here are instructions on how to build a raised bed garden. Check out the planting guide below for some ideas and recommendations on plantings and density.

A Bug Army For Your Garden

Last blog I wrote about controlling harmful insects using pesticides and an Integrated Pest Management approach.  A necessary part of any IPM program is the use of beneficial insects.  Think of them as your own little army fighting for a pest free grow-room 24/7/365.  Having released thousands, yes thousands of Hippodamia convergens (ladybugs) in my grow-room I will say I became more comfortable with insects crawling on me but 99% of the time they were on the job, on a search and destroy mission for any pest intruder attempting to sabotage my garden.  There are lots of beneficial insects to choose from but you must match the pest to the predator, although many predators are not picky and will eat a variety of harmful insects.  Using the chart below you can easily match the kind of insect problem you may be experiencing with the correct predatory insect.

Beneficial Insect IPM Chart

Some interesting facts regarding these insects are:

  • You never should worry about your beneficial insects eating your plants as they will only feed on harmful insects
  • One Lady Bug may eat 5,000 aphids in 1 year
  • Green Lacewings will eat 200 aphids a week
  • Spider mite destroyers will eat 40 mites a day
  • Predatory Nematodes will kill over 250 different types of insects

The Bad Little Beasties Inside

All of us have dealt with some sort of critter, varmint, beastie, or #$*%@#% as I sometimes have called them. I am referring to insects that attack our gardens. There is nothing more frustrating than putting in all the labor involved in making a perfect indoor garden and then having some little critters come in and lay waste to all of our efforts! How these little #$%$@ know to attack our best & most prized plants I will never know. In my time I have battled and waged all out WAR on several different destructive insects. Sometimes I am the winner and sometimes not. So what are we to do?

My suggestion today is accept the things we can not change, change the things we can, and have the wisdom to know the difference. Wait…why does that sound familiar? The point is that it can be very difficult to eradicate an insect population, however like in a natural ecosystem we can establish a balance where an “acceptable” level of insects are left in our garden and an ongoing treatment regime is utilized. To maintain this balance we will use beneficial insects, and organic or non-toxic pesticides (as needed.) This approach has gained a lot of support as of late, and is better known as IPM or Integrated Pest Management. IPM is an approach that combines a wide array of crop production practices with careful monitoring of pests and their natural enemies. IPM practices include use of resistant plant varieties, biological controls (such as beneficial insects), and judicious use of pesticides. IPM systems anticipate and prevent pests from reaching economically damaging levels.

Next blog I will discuss beneficial insects, today I would like to talk about my favorite organic insecticides. The first group of insecticides we will call sufficants include the following products: Neem Oil, Organocide, Einstein Oil, Safer Insect Killing Soap, etc. These are oils and soaps that work by covering the exoskeleton of insects which they breathe through and literally suffocating them to death. This type of insecticide is an effective method for spot treating of insects that are slow moving. However, it is less effective on fast moving insects, flying insects, and egg or larval stages of most pests.

The second class of insecticides is the knock down type. This group works by impairing the central nervous systems of most types of flying and crawling insects, blocking nerve junctions so that nervous impulses fail, and the insect dies. The most common active ingredient in this type of insecticide is derived from the chrysanthemum plant and is called Pyrethrum. It can be found in products under the names: Doktor Doom Spider Mite Knock Out, Pyrethrum TR, Don’t Bug Me, or Safer Houseplant Insect Killer. Beware of the synthetic or manmade Pyrethroids which are not organic. Pyrethrum is highly effective on most pests but is only effective if it comes in direct contact with the pests. It is short lived as it deteriorates in the presence of light within 12 hours.

Now my personal favorite Azamax, this insecticide is derived from the Neem plant but is not a sufficant. It was discovered that plants treated with Neem oil seemed to show some future resistance to insect attacks. Research found that there is a compound in Neem oil called Azadirachtin which was responsible for this insect resistance. Azamax is essentially Neem oil distilled down to get a much, much higher concentration of Azadirachtin. Azamax has 3 modes of action to control insects. First it prevents insects from feeding on the treated plant surfaces resulting in damage prevention. Second it reduces the hatchability of insect eggs resulting in population reduction. Finally it interferes with insect reproduction resulting in reduction of egg-laying. All of these combine to drastically weaken, and over time destroy populations of harmful insects. One of the best things about Azamax is it is systemic meaning absorbed into the plant’s tissue so you do not actually have to contact the insect with it. It is also proven that Azamax’s effect of weakening insects makes other insecticides much more successful because the insects in question are already weak and thus more susceptible to insecticides such as Pyrethrum. Azamax is most effective if it is used before an insect attack and reapplied on a regular basis. Azamax is also not harmful to beneficial insects or bees.

Remember it is better to prevent an insect attack than to have one, but they will eventually find your garden. Integrated Pest Management will allow you to control the damage caused by pests and not devote all your time to pest control.

– Doctor Dave