Soil Preparation

Get down and dirty with it.

Soil Type:
Preparation of your garden soil largely depends on what type of soil you have. There are 3 basic types of soil: Clay, sand, and loam. Scoop up a handful of damp soil and squeeze it into a ball. If your soil readily holds a tight shape, it is clay. If it holds its shape somewhat, but can be easily crumbled again, it is loam. If it does not hold any shape at all, it is sand.

Clay and heavy clay soil has tightly-compacted small particles. It holds moisture, but does not drain well. Clay will be hard and compacted when dry and may form large cracks, sticky and clumpy when wet, and air cannot reach the roots.

To amend clay soils, you need to add quite a lot of organic material. Compost, manure, mulch, dry grass clippings. Even commercial potting soils will greatly improve the porosity of clay, as they are mostly smaller chips of pine bark mulch. Using the old potting soil from dead houseplants, or what you have removed when repotting. A high-quality, but inexpensive brand is Miracle-Gro Garden and Vegetable soil. Adding sand, if you have access to some, is also perfect for improving clays. I lived in a heavy black-clay area for some time, and was able to haul in a truckload of sand from this property to amend my garden, along with plenty of compost. I have seen sources saying to avoid adding sand, but I have not had trouble with it, and in fact found it helped immensely, with organic matter, of course.

If your clay is too thick and hard to break up, or contains too many rocks, you may be better off building raised beds, and filling those with compost and good soils. You can begin composting directly in the beds, and fill the rest of the way with rich soil you have brought in from somewhere else, or purchased. Even once a garden area is amended , the surrounding thick clay would prevent drainage, which may prove to be too wet for some vegetables.

Sandy soil is at the other end of the spectrum. It contains large, loose particles which permit very fast drainage and evaporation. Often sand is too dry. Sand is much easier to amend than clay, though, and much more pleasant to work with. The back-breaking work of breaking new ground and removing rocks and weeds goes much smoother with loose sand.

Sandy soils typically only need extra organic matter to grow high-quality vegetables. Compost and manure work fine, and you can always add old potting soil if you like. Sandy soils especially should be surface-mulched to retain moisture around the plants' roots. This can be done with leaves, hay, bark chips, grass clippings, black plastic, or even aluminum foil for winter gardens to reflect extra heat and sunlight back to the plants. With the organic mulches, you can rake it up again after harvest to re-use, and till under whatever has begun to decmpose. Mulches also inhibit weeds. Make sure you wait until your vegetable plants have sprouted, or your transplants are in the ground before mulching.

Loam is the perfect mixture between clay and sand. It is light and loose, but retains plenty of moisture and nutrients. Often, you will only need to add a minimum of compost or manure to loamy soils.

Soil pH and nutrients:
Dirt is not just a foothold for the roots and a sponge to hold the moisture. Plants also gather most of the nutrients and minerals essential for growth from the soil. The acidity of soil, or pH, is also a major factor, much like the pH of aquarium water for anyone who has ever raised fish (sucessfully anyway). Soil testing kits can be purchased that measure pH and indicate amounts of nitrogen, phosphorus, and potassium your soil needs. A more comprehensive testing can be done by sending a sample to your county agricultural extension agent at your local university. Texas A&M offers this service for about $17 for our area, and provides information of what should be added to improve the soil, as well as vegetable varieties to choose.

pH: Acidity or alkalinity is measured on a pH scale from 0 (most acid) to 14 (most alkaline); a pH of 7 is considered neutral. When pH is too high or too low, the availability of nutrients to the plants is reduced. Although most things will grow between 4 to 8, most fruits, flowers, and vegetables do best between 6.5 and 7.0.

Alkaline soils typically range at 7.5 to 8.5, and cause iron to become unavailable to plants. Copperas, compost, sulfur, iron sulphate, or cottonseed meal should be added to reduce pH. Acidity it not typically a problem in our area, and can be reduced by adding lime. If all else fails, use plants tolerant of your native soil.

Nitrogen (N) stimulates growth and plant proteins, and gives them their righ green color. It is especially important for leafy vegetables, and large-leaf plants. Lack of nitrogen results in yellowed leaves, or the plants dropping their leaves. Stunted growth, small leaves, bud delay, few flowers, and small fruit can also be indicators of nitrogen deficiency.

Phosphorus (P) stimulates vigorous growth of seedlings, fibrous roots, and seed production. Important for better use of soil moisture and production of sugars. Phosphorus deficiency is similar to nitrogen deficiency, but leaves are dull green, and often tinged with purple.

Potassium (K) saids in normal cell growth and acts as a catalyst in the formation of protiens, at, and carbohydrates. Lack of potassium results in leaves that turn ashen and have curled tips and edges.

Organic Sources of Fertilizers:

Fertilizer Nutrients Supplied How to Apply
(rate per 100 sq. feet)
Alfalfa meal 5% N, 1% P, 2% K 2 to 5 lbs. on surface, or work into soil. Adds organic matter.
(dried animal blood)
10% N 1 to 3 lbs. Rake into soil surface. Lasts 3 to 4 months. May repel rodents and deer.
(finely ground, steamed animal bones)
11% P, 1% N, 24% calcium Broadcast before planting when soil temp. is above 55*F. 1 to 3 lbs, depending on your soil's phosphorus supply. work into top 6 to 12 inches. Lasts 6 to 12 months, use only on acidic soils because calcium increases alkalinity.
Compost 0.5-4% N, P, & K Apply 1 to 4-inch layer in spring and/or fall on surface, work into soil. Adds organic matter.
Cottonseed meal 6% N, 2% P, 1% K 1 to 3 lbs, work into soil. May contain pesticide residues.
Fish Emulsion
(liquid concentrate)
4% N, 1% P, 1% K, 5% sulphur Dilute according to label directions. May have odor.
Fish Meal
(dried ground fish parts)
6% N, 3% P, 3% K 1 to 3 lbs at planting, depending on soil fertility. If side-dressing, use the same rates per 100 feet of row. Lasts one season.
Granite meal, Granite dust
(ground granite rock)
3-5% K, 67% silica (sand), 19 micronutrients Broadcast 10 lbs if soil is low in potassium, 5 lbs if moderate potassium, 2.5 lbs if adequate potassium. Rake into soil surface. Application can last 10 years.
Grass clippings 0.5% N, 0.2% P, 0.5% K 1- to 2-inch layer fresh, 2- to 4-inch later dried. Adds organic matter.
5-7% K, 32 micronutrients, up to 50% silica (sand) In autumn broadcast at same rate as Granite meal. Sand-based fertilizer mined from dried ocean deposites.
Gypsum, land plaster
(calcium sulfate powder)
22% calcium, 17% sulfur Broadcast 1 to 4 lbs Loosens clay and neutralizes excessive sodium or magnesium.
(seaweed, dry form)
NPK negligible, 60 micronutrients, plant-growth hormones 1 lb on surface, work into soil. Adds organic matter.
(seaweed, liquid form)
NPK negligible, 60 micronutrients, plant-growth hormones 1/2 tablespoon per gallon. Drench soil or spray on leaves every 2 weeks for leafy vegetables, every 3 to 4 weeks for other plants.  
(sulfate or potash magnesia)
22% K, 11% magnesium, 22% sulfur No more than 1 lb on surface, or work into soil. Sold as Sul-Po-Mag and K-Mag. Excess can burn plants.
(solid animal waste, aged)
Cow: 2% N, 2% P, 2% K
Horse: 1.7% N, 0.7% P, 1.8% K
Poultry: 4% N, 4% P, 3% K
Sheep: 4% N, 1.4% P, 3.5% K
Pig: 0.5% N, 0.3% P, 0.5% K
10 to 20 lbs on surface, or work into soil. Adds organic matter. High nitrogen in fresh manure can burn plants, compost first, or dig into soil one season before planting.
Wood ash 7% K, 20% calcium, some micronutrients No more than 2 lbs every 3 to 4 years, on surface, or work into soil. Do not use on soil with pH above 6.0 because calcium raises pH.
Worm castings
(worm manure)
Not significant Apply 25 lbs if soil is low in organic matter, 10 lbs if moderate organic matter, and 5 lbs if adequate organic matter. Spread on surface or work into soil. Adds organic matter and improves soil structure.
(table compliments of Better Homes and Gardens' New Complete Guide to Gardening)

Choose your site
Vegetable plants need a maximum amount of sun each day to produce, so plan your garden in the sunniest spot available. You must take into consideration the changeing position of the sun during different times of the year. Avoid planting in areas that have been previously contaminated by grease, oils, or poisons.

Breaking ground
Starting a new garden is the most difficult part. You will need to break up your soil, and remove all weeds and large rocks. We have quite a bit or iron-ore rock of all sizes here, and I typically pick out anything larger than a silver dollar. I save the rocks for using elsewhere. The smaller ones can be used for mulch and decoration around cacti, or used in the bottom of pots to raise the soil level and improve drainage. Large rocks can be used for borders and other landscaping purposes, or weighting down plastic covers in winter.

Using a shovel or garden fork, dig down and push up the soil, but do not turn it over. Continue working a square area, usually a few feet wide and across is a good starting point. Now, using a cultivator or garden rake, you can break up the top layer of soil and rake out the weeds. You may need to use a fork on clay soils, and "chop" it a little more before raking. A power-tiller may be better if you are planning a large garden area, but smaller gardens are usually best for beginners. You will still need to remove the grass and weeds, or else they will sprout again.

Continue this process until you have your garden area loose, and free of weeds and grass. Pick out any rocks as you go along, too. Keep a cart or buckets handy to collect the "junk" in, dump your weeds into the compost, and find an out-of-way place to dump the rocks.

An alternative method to raking out weeds is to cover the area with layers of cardboard, newspaper, or black plastic. You must allow at least 2 weeks to kill off the weeds and grass, and the cardboard or paper will have to be weighted down. This method is excellent for raised beds, since you can leave the materials on the ground, and simply build and fill on top of the paper.
To use black plastic, you will need to spread and weight it down with rocks, bricks, or boards. Another method involves "cooking" the weeds and grass by burying the edges of the plastic in a small trench with dirt, creating an air-tight seal. Soil will still have to be tilled and rocks removed, however.

Spread your organic matter over the garden area, and loosely turn the soil with your shovel or fork. Mix soil at an angle, turning from side to side rather than inverting it. Only mix to a depth of about 5-6 inches to avoid disturbing the soil structure too much. Or run your tiller over the area. Once mixed, you can rake out and break any large clumps that might be left.

Shaping things up
Your soil is now ready for planting, but you will probably want to make your plants easier to access without having to walk on the growing soil. If you choose a long-row garden, use a hoe and bring up the soil in large mounded rows, so that you have a "ditch" between them. These ditches can be used for watering, and as a walkway to access the plants.

If you prefer beds, you can lay out your border materials now, or before the organic material was added.

Place trellises where needed for growing peas, pole beans, or other vines. Tomato cages should be placed around the transplant after it is in the ground.