Soils
Soils: Good soil is fundamental to successful gardening, landscaping, and healthy houseplants. Balance structure, nutrients and pH to compliment plants' needs.
Most gardens require a 6.0 to 7.0 pH to support either flowers or produce. Finding the right combination of soil properties to promote drainage while retaining moisture ensures healthy plants.
Adding organic material and fertilizer can correct most soils.
Composting effectively recycles many kinds of yard wastes and provides organic matter to replenish soils.
Mulch protects good soil by reducing the need for watering. Just 4" of mulch can reduce soil temperature as much as 20 degrees.
Soil testing provides the most effective method for soil evaluation. Contact the county extension service or local garden center for more information.
Prepare garden soil during autumn to increase benefits through the winter months. Good spring soil preparation improves productivity during the growing season.
Read the following articles to learn more about soils.
Why buy a lead soil testing kit?
Worth the investment
Lead in your soil is a serious issue that can easily be dealt with through the purchase of a lead soil testing kit. The most common occurrence of lead in soil comes from acid rain washing lead off of exterior house paint and into the yard. Car exhaust from nearby highways can also contribute to the problem.
Affordable and important info
However it may happen, presence of lead is quite possible and the costs of testing are reasonable. Home test kits are sold in packs containing anywhere from six to 100. Generally, the cheaper ones range in price from fifty cents to just under two dollars. The developers of such tests boast accurate results in record time with little effort. However, as with most home tests, the various solutions and swabs leave a lot of room for non-professional human error.
Other lead soil testing kits have inflated prices but are still reliant on proper procedure from a non-professional. They are carried out entirely at home and offer results in less than 30 minutes. Six tests are included for about 50 dollars.
Reliability concerns
The U. S. Department of Labor expresses confidence in these kits, noting that they do detect lead at the necessary levels. However, since so many substances interfere with the reading, often a negative result cannot be trusted. If you still suspect lead after getting a negative result, you may want to look into sending some materials to a lab. These kits are about 40 dollars and provide results in a matter of days.
If you fear there might be lead in your soil, the less expensive lead tests are an economical and easy way towards piece of mind. The existence of interfering chemicals may mean your best decision is paying the higher price up front and shipping off some samples.
Soil testing FAQ’s
I am not a professional gardener; why should I be testing my soil?
Taking cues from pros is never a bad idea. A soil sample is affordable, quick, and invaluable if you’re shooting for a good season. Many good-intentioned homeowners profess a great devotion to their lawn or garden, but end up pumping it full of unnecessary chemicals that are at best wasted and at worst hazardous to the environment. A little time and money up front can lead to greener, lusher plant life and a substantial reduction in cost.
How often should I test my soil?
Definitely at least once to know what you’re dealing with. The only way to ascertain whether the soil is acidic, neutral or alkaline is with a soil test. Upon learning the composition of the soil, your decisions on what to grow and how to care for your lawn will be much more educated. Much like carpentry; measure twice and cut once. Before making any major landscape changes, test your soil again to prevent unforeseen problems due to changes in soil composition.
What are my options?
Kits are available at garden stores everywhere. They are affordable, easy to use, and fairly reliable. It is important to follow the instructions closely and use distilled water with soil testing kits. And since you are probably not a geologist, it may be a good idea to corroborate the results with a second test.
If you live in an area with an agricultural university, they probably offer this service for around ten dollars. You can rely on the results to be accurate and thorough. There are also plenty of commercial labs advertised in gardening magazines, stores and on websites.
How do I take a sample?
The instructions will be specified on your test kit or by the testing agency. Overall you want to avoid testing recently treated soils, use sterile equipment, and take your samples from 3 to 6 inches deep. If you have several purposes for your soil, you may want to test separate samples to account for any variances.
What is this going to tell me?
A thorough test will tell you the consistency of your soil, the presence of organic matter, and the pH level. If your soil is loamy, you will treat it differently than a soil with more clay. Specific knowledge of organic matter can glean information on proper treatment plans, as can knowing the pH level. Usually, labs don’t test for everything, so tell them if you want your sample tested for lead or other specific nutrients. A gardening center or lab can then assist you in how to turn the results into a plan to keep your yard healthy.
Potting soil terms
Charcoal - Not to be confused with your charcoal briquettes, adding this fortifies your soil with potassium salts and will raise the pH significantly. It is mostly used for facilitating drainage and air circulation. Obviously, avoid in soils with adequate potassium and high pH levels.
Compost - The compost pile rouses intense passion in proud gardeners. Throw your organic kitchen garbage, herbivore animal waste, and a ton of chopped dried leaves and assorted yard waste in a bin. A committed grower can churn out good compost in about a month, but most will take at least a year.
Humus - Arguably interchangeable with compost. Humus is simply the dark organic matter left after decomposition. It is too dense to be used as potting soil by itself, mix it with sands and minerals for a looser texture.
Limestone - This is used on soil with excessively high pH levels. Dolomitic limestone contains calcium and magnesium carbonate, so it should be reserved for acidic soils low in magnesium. Most gardeners use calcitic limestone to lower the pH levels in soils, it supplies necessary calcium as well.
Loam - Term used for a quality soil used in compost or a base for potting soil. Sand, clay and fiber will all be present in good loam.
Peat Moss - A valuable asset renowned for its ability to retain air and water. Peat moss is partially decomposed sphagnum moss or sedge and is used in making both compost and potting soil. Also known as Feat Moss or simply Peat.
Perlite - You’ve seen these little white grains in soil before. They are a porous mineral included to aid in retaining moisture and air.
Potting Soil - What makes a potting soil anyway? It should be light, loose and sterile. Of course it is rich in nutrients but differs from topsoil in density due to the presence of several non-binding elements like coarse sands and minerals.
Pumice - A lightweight rock that will float on water and is often employed as an abrasive for cleaning and polishing. For potting soil it functions like vermiculite or perlite, retaining water and allowing drainage.
Vermiculite - Yet another handy mineral, heated to expand and form a lightweight granule that soaks up water and air. Also referred to as “mica.”
How to use a soil thermometer
A little effort goes a long way
Many sources contend that the correct soil temperature is equally as important to a flourishing crop as the right time of year. Planting in soil a bit too cold could result in seed rot, slow germination, growth problems and disease.
Just 10 degrees F in soil temperature will delay cucumber germination an entire week, and peppers plants can be stunted all season if planted under 70 degrees F. Indeed, properly using your soil thermometer could save you from a season scarce of your favorite vegetables.
The calendar says ‘plant’
Old farming wisdom about planting when the ground is workable is rather obsolete now. Instead, shoot for consistent ground temperatures over three mornings. For planting seeds, get a measurement at about two inches of depth. If you are transplanting, measure four to six inches deep. Of course, it is best to wait a few minutes before taking a reading. The following information will get you on the right track.
- 60 F – tomatoes, cucumbers, snap beans
- 65 F – sweet corn, lima beans, mustard greens
- 70 F – peppers, watermelons, squash, southern peas
- 75 F – okra, cantaloupe, sweet potatoes
Finally, remember to make it easy on yourself when using the soil thermometer. Many display the temperature on the side which means you must take it out of the ground to read it. If you want to leave it in the ground for long periods of time, consider purchasing a thermometer with a brightly colored head so you can locate it quickly. If you are going to be measuring the temperature of a compost pile, you’ll want a soil thermometer with a range past 160 degrees F. Some thermometers don’t read past 140 degrees F and would be useless in killing off resilient pathogens and weed seeds.
Using a soil thermometer is not quite as easy as it sounds, but almost.
How to make potting soil
Impressive garden, but who made your dirt?
Your basic potting mixture
Use for potting rooted cuttings started in sand
- 2 parts sharp sand
- 1 part loam
- 1 part leaf mold
Try replacing leaf mold with peat moss if the plant is acid tolerant.
Potting soil for mature plants
Plants like the garden geranium, fuchias, chrysanthemums and palms grow well in this mixture.
- 1 part sharp sand
- 2 parts loam
- 1 part leaf mold or humus
- 1/2 part dried cow manure
- A 5-inch flower pot of bone meal
Plants such as begonias, ferns, and primulas need the humus or leaf mold doubled.
Hardwood plants
Azaleas, Ericas, Daphne, and some ferns like a little peat moss.
- 2 parts sharp sand
- 2 parts loam
- 2 parts peat moss
- 1 part leaf mold or humus
- 1/3 part dried cow manure
For the tougher ones
Cacti and succulents thrive in this one.
- 2 parts sharp sand
- 2 parts loam
- 1 part broken flower pots or small pieces of soft brick
- 1/2 part leaf mold or humus
- A 5-inch pot of bone meal
- A 5-inch pot of ground limestone
Acquiring these ingredients may be something of a chore, but once you have them on hand you’ll be fully prepared for any potting need. Remember to clean pots thoroughly before planting and to soak new clay pots for several hours (or weeks for the meticulous gardener) so they won’t steal water from the plants.
If you suspect that maybe having all the materials for every different type of potting soil is too much, many commercial varieties are available. Foxfarm offers a first-rate potting soil based on earthworm castings and bat guano. Pro-mix is an indoor and outdoor potting soil made from Canadian peat moss. Aussie Gold has created an organic soil that is insect resistant and will not compact on your plants’ root systems. These brands are all affordable and offer professional results to those who aren’t looking for complete autonomy in their garden.
Types of soil
While leaves, flower and fruit capture our attention, much of a plant's growth activity occurs in its roots. Proper soil sustains plants' systems for health and growth.
Evaluate soil types by 3 basic properties
- Structure.
- Nutrients.
- pH level.
Structure describes density.
- Clay is heavy and sticky.
- Sand is light and dry.
- Loam is a balanced combination of clay, sand and loam.
Nutrients provide food necessary for plant growth.
- Nitrogen nourishes stems and foliage.
- Phosphorous sustains roots and flowers.
- Potassium promotes food production.
pH Level
Correct soil pH allows the root system to absorb crucial nutrients
The pH scale runs from 0 to 14.
- A pH level of 7.0 is neutral.
- Any pH below 7.0 is acidic, the further below the more acidic.
- A pH above 7.0 is basic, or alkaline, and like acids, the farther from 7.0 the more basic.
Typically flower and vegetable gardens require a 6.0 to 7.0 pH level.
Testing
Soil testing, available through county extension services and many local gardening centers, provides the most efficient determination of soil types. Follow the sample collection instructions carefully for most accurate results. Look for tests that report organic content (typically only 1%, needing to be at least 3%).
Making adjustments
Establishing proper balance between retaining moisture and draining well yields productive soil types. Roots need moisture available to sustain them during dry periods between rains or watering, yet won't tolerate standing water. Soil needs to be porous enough to allow air to circulate through the roots, yet strong enough to support the plant's mass for growth.
Whatever soil type adjustments are made, work in to a depth at least twice the depth of the addition – work two inches of top layer in at least four inches, three inches of top layer in at least six inches, etc.
Changing the pH level of garden soil:
- Use 10 pounds of lime per 100 square feet to raise soil pH level 1 point.
- Use 10 pounds of sulfur per 100 square feet of soil to lower pH level 1 point.
- Wait two weeks after adjusting pH before adding fertilizer.
Adding organic matter:
- Replaces depleted nutrients.
- Both breaks up clay type soil to reduce its stickiness and helps sandy type soil retain moisture.
- Organic matter sources:
- Rotted manure.
- Leaf mold.
- Peat moss.
- Compost.
Cover crops like peas, beans or buckwheat, are grown, then cut and worked into the soil to increase organic matter.
- Buckwheat grows well in many climates and works in fairly easily.
- Harvest buckwheat when all plants show bloom production.
- Cut to ground level and work into the soil with the roots.
- Large garden areas may require tilling.
When adding organic material work at least a 1:3 ratio. Work two inches of compost material through six inches of soil.
Applying fertilizer
Work in fertilizer with organic material when preparing the garden. Broccoli, cabbage, cauliflower, corn, onions, peppers, potatoes, tomatoes and other high feeding plants require side dressing fertilizer boosts.
Working the soil
Make soil adjustments during autumn to allow soil to blend well before production. Leave the spaded are rough to allow winter conditions to maximize benefits.
Be sure soil is dry enough to work in the spring:
- A clenched handful should break apart rather than cling together.
- Working the soil while it is still too wet causes compression, reducing oxygen needed for microorganisms, earthworms, plant growth, etc.
- Add organic matter two weeks prior to planting. Work four inches of top layer six to 12 inches deep.
Potting soil benefits
Use potting soil to save time when providing suitable soil for different kinds of plants.
- Organic matter retains moisture and improves drainage.
- Soil provides weight and minerals.
- Ferns require more moisture retention.
- More porous soil is better suited to succulents, including cactus.
Soil straight from the garden may be too densely compacted for use in container plantings, especially houseplants, with little room for air or water. Soil-less potting mixes contain no dirt, but may include peat moss, vermiculite or perlite and offer the added advantage of low disease risk for plants. Their lightweight property may cause difficulties with smaller containers in windy areas.
Potting soil components
While there are no standards for content, packaged potting soil mix has typical components:
- Dirt or mud.
- Organic matter – like peat moss, compost, worm castings, ground bark.
- Vermiculite – silicate material for air space and drainage.
- Perlite – volcanic material, lightweight provision for air and drainage.
- Fertilizer – typically slow release for extended benefit.
To create a general use, economical potting soil combine:
- EITHER 3 parts ground bark with 2 parts potting soil and 1 part perlite,
- OR 2 parts peat moss with 1 part potting soil and 1 part perlite.
Combine 2 parts peat moss to 1 part potting soil and 1 part vermiculite to make potting soil for ferns.
Compost, rich in organic matter, can successfully be used for potting soil. Adding material to increase it porosity may be necessary. Materials used to create beneficial air pockets in potting soil include:
- Vermiculite.
- Perlite.
- Sand.
- Bark.
Due to its fluoride content, avoid perlite in soil for peace lilies and spider plants.
Use
In general roots should occupy 75% of the container soil. Potting soil must balance moisture retention between watering or rains and sufficient drainage to keep roots from submersion in standing water.
When adding potting soil, do not tamp down around the plant as this reduces air capacity and drainage capability. Monitor plants and add another inch of soil when needed. Replenish the top two inches of soil each spring. Remove any mulch before applying replenishing soil.
Be sure packaged potting soil is sterilized – meaning no weeds or insects.
Have soil that needs to be sterilized? Here's a simple method to assure clean soil. Place soil in a shallow pan with a raw potato in the center. Bake in the oven until the potato is thoroughly cooked.
How much to buy?
- Typically sold in dry quart or cubic foot amounts.
- One cubic foot, nearly 26 dry quarts, will fill 2 to 3 one-gallon containers.
Uses beyond houseplants:
- Window boxes.
- Outdoor container plantings for flowers or vegetables.
- Work into soil for flowerbeds or garden vegetables that prefer lighter soil.
Using potting soil for versatile container plantings
If it can hold enough soil and provide drainage when over watered, it can become a planting container. Planting in containers offers the opportunity to create ideal conditions for plants that may not be regional natives or to maintain a themed indoor or outdoor décor with plant groupings and accents.
- Carefully select soil to address moisture and drainage needs.
- Stone mulch at the surface and at the bottom of the container for optimum drainage prevent over saturation with standing water.
- Be sure to maintain these conditions even after the plants are established.
- Besides decorative foliage and flowering plants, favorite fruits and vegetables successfully grow in containers.
- Containers can be rearranged or moved to provide a home or garden with flexibility in use and appearance.