Spring Raised Bed Vegetable Gardening: A Guide to Organic Soil Amendments & Organic Fertilizers

Growing in a Raised Bed is So Easy Even a Child Can Do It!

Growing in a Raised Bed is So Easy Even a Child Can Do It!

The idea of planting a garden can be daunting. There is so much information and advice as well as countless products and additives to choose from, it might feel as if you need a PhD to grow a tomato. The fact is that everyone can easily grow an edible garden. Similar to buying real estate, the most important choice a gardener makes is location; you cannot grow sun loving plants (which most vegetables and fruit are) in dense shade. Most vegetables (excluding leafy greens like lettuce and cabbage) require a minimum of six to eight hours of direct sunlight per day. Most of us can find an area that gets enough sun, but what are you to do if the area with the correct sun exposure does not have healthy rich soil? The answer is simple: build a raised bed garden.

Raised bed gardens have several advantages over traditional in-ground gardens. First, raised bed gardens are constructed above ground, lending themselves to easier planting, tending, and weeding. Raised beds are little more than large container gardens and can be placed anywhere, regardless of the quality of soil underneath. Also, raised bed gardens are ideal for square foot gardening. You can build them out of wood (do not use pressure treated wood as the chemicals in the pressure treated wood can leach into your soil, and your plants), or buy a raised bed garden kit. Another option for someone that wants a raised bed garden but doesn’t have the time or tools to build one is to use a large fabric aeration pot. Aeration pots are fabric containers that come in sizes from 1 gallon all the way to 300 gallons. The benefit of aeration pots is that they prevent the plant’s roots from becoming root bound, while encouraging a more robust root systems with greater surface area in contact with the soil for improved nutrient absorption.

Root bound plants like the one in this photo can stunt a plant's growth.

Root bound plants like the one in this photo can stunt a plant’s growth.

Viagrow™ Fabric Aeration Pots prevent plant's roots from becoming root bound.

Viagrow™ Fabric Aeration Pots prevent plant’s roots from becoming root bound.

Once you have built your raised bed or purchased an aeration pot, now comes the all important choice of what to fill it with. I prefer a high quality potting soil like Fox Farm’s Ocean Forest which is loaded with organic fertilizers and micro-organisms. However if that does not fit your budget, another less expensive option is topsoil, which is sold by the bag at every hardware store or sold by the truck load. It can be used as base for your garden soil, but topsoil is not ready to use just yet. I recommend when buying topsoil to make sure it has been screened, ensuring that large pieces of organic debris and rocks have been removed. Plan on adding organic matter and organic fertilizer to the top soil; it will guarantee a bountiful harvest of your favorite fruits and vegetables.

The best way to add organic matter to soil is by adding a rich compost. Compost is decayed organic matter, and it is one of the best things you can add to any soil. You may have the notion that a compost pile is a big, ugly, smelly pile of leaves and lawn clippings, but that is not necessarily true. Today people have options of homemade compost piles, well constructed compost bins, and stylish compost tumblers. These provide everyone the option of making their own nutritious organic soil inexpensively. You can also improve the soil structure and improve the moisture retention and/or drainage of your garden soil with the addition of products like perlite, shredded leaves, peat moss, coconut coir, and composted bark sold as “soil conditioner.”

Aside from compost there are several organic fertilizers and additives that can be added to improve your garden soil. One popular option for adding organic matter to soil is to use composted animal manures. There are several kinds to choose from including: seabird guano, bat guano, cow manure, horse manure, and chicken litter. Generally, manures from animals that eat vegetation are preferred to animals that eat meat. Animal manures vary greatly in the nutrition they will provide your garden due to the different diets of the animals that produce the manure. When possible, it is best to use composted manures and guanos in your soil; fresh manure is best placed in your composter to age and breakdown before it is used or you risk burning your plants. An added benefit of animal manures and guanos is that they provide an excellent source of beneficial micro-organisms which add to your soil’s ecology. You also have the option of adding beneficial fungi and bacteria with products like Mykos and Azos.

Other options for amending soil include the following organic fertilizers and additives:

Rock Phosphate
A natural granular source of phosphorous and calcium in addition to several trace minerals. Rock phosphate is an excellent source of phosphorous which promotes cell division, photosynthesis and respiration. Also encourages the growth of earthworms and soil bacteria that enrich and aerate the soil. Slow release so it will not leach away like chemical blossom boosters. Apply 1-3 lbs. per 100 sq. ft. for gardens.

Blood Meal
A slow release organic nitrogen source. Excellent as a top dressing when extra nitrogen is needed. Stimulates bacterial growth. Use 2-3 lbs. per 100 sq. ft or as a top dressing.

Bone Meal
Steamed, finely ground bone provides phosphorus, calcium and nitrogen. Promotes strong, vigorous bulbs, healthy root systems and good blooming. Excellent for flowers, roses, garden bulbs, shrubs and trees. Use up to 5 lbs. per 100 sq. ft.

Greensand
Contains 22 minerals and helps loosen compacted clay soils. Highly recommended for conditioning pastures, lawns, orchards, fields, and gardens. Apply 2-4 lbs. per 100 sq. ft.

Worm Castings
A pure all natural plant food produced by earthworms. Helps develop foliage in plants and improves aeration of the soil. Worm castings are also a source of nitrogen. Use in gardens and flower beds at rate of ½ cup per plant every two months. In potting mixes add 1 part earthworm castings to 3 parts soil. For roses mix 4 cups into soil around each plant.

Sulfur
Sulfur is excellent for lowering the pH of soils for growing blueberries, rhododendrons, azaleas and other acid loving plants. Use according to soil test recommendations – do not over apply. Maximum use ¼ lb. per 100 sq. ft.

Micro Pelletized Gypsum
Pelletized calcium sulfate; supplies calcium and sulfur while loosening clay soils, aiding aeration and water penetration. Use when calcium and sulfur are needed, and pH of the soil is alkaline. Use 2-3 lbs. per 100 sq. ft.

Garden Lime
A natural liming material which supplies additional calcium and helps maintain a near neutral pH in your soil. Apply 3-5 lbs. per 100 sq. ft.

Once you have built your bed, added your soil, and amended it with lots of organic matter and fertilizer, it is time to plant your seeds or seedlings. Starting seeds is easy to do with a Viagrow™ Seed Starting Kit. Another option is to visit your local nursery and buy vegetable seedlings; ask them what varieties will perform best in your area. Water regularly (as needed) and top dress around the base of your plants on a monthly basis to ensure your plants have plenty of food. You will be eating your harvest in no time.

A raised bed garden can produce enough for a family of 4 in a very small area.

A raised bed garden can produce enough for a family of 4 in a very small area.

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

Photo courtesy of freedigitalphotos.net

Photo courtesy of freedigitalphotos.net

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.