Spring Planting





In this workshop, instructor Erin Higgins, the Education and Giving Grove Coordinator at The Big Garden, teaches you how to prepare a bed for planting and proper planting techniques for seeds & seedlings. She also shares when to plant different varieties and explains bio-intensive planting, which will help you get the most out of your small garden.


The following calendars, charts, and tools can be found online. Just follow the links. When seeking out other guides, calendars, and tools on your own, keep in mind which USDA Hardiness Zone you’re growing in. In Omaha, we’re in zone 5b. Your local university’s extension can be a great, localized resource, but often online tools are customizable.


HANDOUTS


WHAT IS SOIL?

and why is it so important?

SOIL is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life.


AN IDEAL SOIL has the following composition: 25% water, 25% air, roughly 45% minerals, and 3-5% organic matter.



THE MINERAL COMPONENT of soil is some mixture of sand, silt, and clay. Sand particles are very large, silt particles are relatively small, and clay particles are very, very small. Every soil has these particles in varying proportions, and there is very little you can do to change these ratios.


THE ORGANIC COMPONENT of your soil is made up of both macro- and micro-organisms. Living things like nematodes, earthworms, beetles, bacteria, fungi, and protozoa. It also consists of dead plant and animal matter in varying states of decay. You can add organic matter to your soil in the form of compost or living or dead plant matter (i.e. mulches or plant residue from harvested crops).


A full half of an ideal soil is made up of WATER AND AIR which all of the living organisms in your soil and the plants you want to grow need to sustain their lives. This is why COMPACTION is something we want to avoid. Soil becomes compacted, and the pockets of air and water disappear, when we step on soil unnecessarily and when we use excessive tillage.



Healthy soils are teeming with life. Researchers have calculated that a double handful of biologically active soil will contain more units of life than there are people on the face of the earth. And these organisms form an INTRICATE ECOSYSTEM that has developed over millennia. A smart gardener doesn’t think about just feeding the plants that they want to grow, but more importantly feeding and supporting this intricate ecosystem of organisms.



SOIL AGGREGATES

why they're important and how to build them

SOIL AGGREGATES are groups of soil particles that bind to each other more strongly than to adjacent particles.


The space between the aggregates and within the aggregates provide pore space for retention and exchange of the AIR AND WATER that is so important for all of the living organisms in the soil. The larger pores between aggregates also allow space for roots to move down through the soil.




YOU CAN PROMOTE AGGREGATION IN YOUR SOIL

Certain aspects of your soil will lead to or detract from its ability to form aggregates regardless of what you do. Soils with higher clay content or higher iron and aluminium oxide content tend to aggregate better. A soil test will help you determine what you’re working with in terms of these properties.


More importantly, though, certain practices can increase soil aggregation. These things are in your control.


Adding organic matter to your soil promotes aggregation. As the micro-organisms in the soil break down the organic matter, they create and secrete compounds that act almost like a glue to bind soil particles together.


Keeping roots in the soil as much as possible promotes aggregation. Living roots produce and secrete what is called root exudates which also act as a glue. As you plan out your garden for the year, think about successive plantings. For example, once you harvest your spring peas, can you use that space for a summer or fall crop like squash? Also consider growing cover crops when you aren’t going to have a harvestable crop in the soil.


Focusing on fungus can also promote soil aggregation. As fungus, such as mycorrhizal, weave their way through the soil, they bind particles together. Fungi love woody plant material, so think about growing perennial crops like raspberries or wild plums. Or utilize wood mulches to keep your ground covered.


YOU CAN ALSO DESTROY SOIL AGGREGATES


When you till you are violently breaking up all of your soil aggregates into finer particles. This allows the soil to become compacted, reduces moisture retention and proper drainage, and leads to soil erosion and loss of organic matter. As much as possible, utilize no-till or low-till techniques in your garden.



WHAT ABOUT HUMUS?

humin, humic acid, and fulvic acid

All fertile soil contains several components: decomposing organic matter, living organisms (including plant roots, bacteria, fungus, worms, nematodes, protozoa, and small animals), and HUMUS


HUMUS is the carbon-rich matrix made of fully decomposed organic matter and is found in any soil containing decomposed organic matter, as well as in compost, worm castings, sphagnum peat moss, and other aged organic matter.

The older and darker in color that a soil is, the more humus it contains.

Humus is made up of lignins, fats, and sugars, as well as three types of chemical compounds called “humic substances”: humin, humic acids, and fulvic acids.

The electronegativity factor of humic and fulvic acids is key in developing and maintaining healthy and sustainable soil. Humic acid and fulvic acid are large, negatively charged particles. And thus attract and bind to positively charged ions, which are all of those nutrients a plant needs (e.g. Mg+, Ca+, Na+, P+, etc.). These large acids then move through the soil to the depletion zone of roots and mycorrhizal fungus, which are also negatively charged, and hand over the nutrients to the roots and fungus.


To PROMOTE HUMUS FORMATION, first make sure that you’re consistently adding organic matter to your soil, in the form of compost or living and dead plant material. Second, keep those living organisms in mind at all times. The earthworms and beetles will break down larger pieces of organic matter before the bacteria, fungi, and protozoa take over and continue the process of breaking down the organic matter into its final state: Humus.



THE RULES FOR HEALTHY SOIL

building humus and promoting aggregation

  1. KEEP YOUR SOIL COVERED. The soil should never be naked. Nude soils promote erosion, evaporation of soil water, leaching and outgassing of nutrients; they weaken soil biodiversity and the nutrient base of the plant symbionts; they reduce capacity of the ground for assimilation of atmospheric carbon, nitrogen, and water. Soil cover can be achieved by means of mulching crop residues or cover cropping systems.

  2. DON’T DISTURB THE SOIL. Use low or minimum tillage to maintain the soil structure and prevent compaction. Tilling and inverting soil layers expose organic matter to oxidation, converting it to CO2 lost to the atmosphere. It also disturbs complex soil ecosystems, impoverishing the soil food web.

  3. RETURN NUTRIENTS TO THE SOIL. Use crop residues, compost, and animal manure. Return the nutrients that have been removed from the soil.

  4. DIVERSITY IS KEY. Diverse mixed plantings promote soil biodiversity, improving biological nutrient fixation and increasing disease resistance of the ecosystem.

  5. CONSIDER PERENNIALS. Once a perennial planting is established, it becomes a no-till area by nature. You’ll likely want to mulch a perennial area to prevent weed suppression or use living mulches like clover which means the soil will be covered. The deep root systems of perennials bring nutrients from further down in the soil profile. And perennials provide food (sugars) to the microbial life in the soil year-round, keeping the soil food web complete.

  6. CROP ROTATION. This is a tidier way to mimic diversity. Using a minimum three-field rotation system and mixed cropping increases biodiversity, reduces pests and diseases, and increases soil mineral availability.

  7. USE COVER CROPS. These not only keep the soil covered which reduces a whole host of issues listed above, but they also increase humus content, act as a fertilizer by helping fix nitrogen and scavenge other nutrients, reduce weed and disease pressure, encourage beneficial insects, promote soil aggregates, add biomass to the soil, and keep the soil food web alive and thriving by providing sugars to all the microorganisms living in the soil. To promote NITROGEN FIXATION use legumes like hairy vetch and winter peas. To increase HUMUS CONTENT use more grasses and clovers.



CROP ROTATION

mimicking diversity

What is CROP ROTATION?

Crop rotation is a process of grouping vegetables by botanical family, and/or by their nutrient and care requirements, and then planting them in different parts of your garden in a rotation. So legumes would be on the northwest side of your garden in year one, and then the southwest side of your garden in year two, etc.



legume, root, leaf, fruit annual crop rotation
crop rotation


The BENEFITS OF CROP ROTATION

  • It disrupts the life cycle of many organisms (insects, diseases, weeds), which otherwise would be able to take up residence more easily.

  • It allows plants with different root systems to penetrate the soil to different depths, thereby improving soil structure.

  • It reduces depletion of nutrient reserves in the soil by alternating crops with different requirements. Root vegetable, leaf vegetable, fruit vegetable.

  • It allows for alteration of heavy feeding crops with light feeding ones. Compost can then be applied one year out of two, for easier management.



CHOOSING THE RIGHT LOCATION

questions to ask yourself

Where will you grow? Backyard, community garden, farm, etc.

What is going on with the SOIL? If there is no existing soil test, get it tested. Especially if you might have lead or other heavy metals in your soil. Check your property's lead history here. We recommend Midwest Labs in Omaha for soil testing.

What is the landscape already doing? Notice what is growing here. What “weeds” or plants already exist? What wildlife? Is there a natural water source? Soil is living. There are millions of different species both visible and invisible around you. How can you disrupt your small ecosystem as little as possible? A garden can provide habitat + food for other species.


Is there full sun? Almost all annual vegetables and fruits require full sun which means 6-8 hours each day.

Is there an option for a south-facing garden? If you can select a location that faces south with nothing blocking the southern edge, your soil will warm up earlier in the season, and stay warm later into the fall.

Is there a slope? Build your garden with the slope, not against it. A gentle slope can help prevent flooding during heavy rains. A steep slope might necessitate doing more landscaping to prevent water from moving too quickly through the garden, though.

Is there water close by?

A water source must be easily accessible. Gardens need water on a very regular basis. Make it easy on yourself!

Do you need to build raised beds?

If your soil is contaminated with lead, you will need to construct raised beds instead of planting directly in the ground. You might also want raised beds if you have mobility issues or for a neater appearance. Never use treated lumber for building raised beds. To fill raised beds, use a 50/50 blend of topsoil and compost. We like to order from Soil Dynamics or Maple 85 here in Omaha.



SOIL TESTING

why it's so important

SOIL ANALYSIS

You can learn a lot about your soil by getting it tested. We recommend going through Midwest Labs here in Omaha. They have a Garden Soil Testing Package that costs $15 and will tell you most of the information you’ll need about your soil: Organic Matter, Nitrate-N, Phosphorus, Potassium, pH, Magnesium, Calcium, Sodium, Soluble Salts, Buffer Exchange, and Cation Exchange Capacity.


For a great explanation of how to interpret your soil test results, go to the following link: SARE Interpreting Soil Test Results


LEAD TESTING

Omaha, like many major metropolitan areas, has a terrible lead problem. Lead in soils is inhaled in the form of soil dust particles and is ingested when people either unwittingly eat soil or eat certain plants that have been grown in lead-contaminated soils. It can be very dangerous, especially for children. Long-term exposure is especially risky.


You need to get your soil tested for lead if you live in Omaha. It may have already been tested and possibly remediated, though. Check out the Omaha Lead Registry’s website.


The Simple Search is recommended. You just type in your address, click the search button, and an aerial view of your home will pop up. Click on your home, and information about whether your soil has been tested, when it was tested, what the results were, if the soil qualified for remediation, and when it was remediated will appear.


Anything below 400 ppm is considered low. We err on the side of caution at The Big Garden, though, and we do not work in soils that are about 100 ppm given that we work with so many children. This is why we build so many raised bed gardens, and you can do the same if you want to err on the same side of caution.


If you want to read more about the different classifications of lead levels, and recommendations on what to do to protect yourselves and your children if you do want to garden in soils that are fairly low, Penn State’s Extension has a great explanation.



BIOINTENSIVE METHODS

a quick introduction

BIOINTENSIVE METHODOLOGY tries to grow as much organic food as possible in the smallest amount of space. The method draws upon a variety of intensive agricultural methods practiced thousands of years ago in China, Greece and Latin America, as well as French intensive techniques practiced in the 1700s and 1800s, and Biodynamic techniques developed in Europe in the early 1920s.


THE EIGHT PRINCIPLES OF THE BIOINTENSIVE METHOD are:

  1. Raised Permabeds – to create a healthy environment for roots and soil organisms

  2. Composting – to provide healthy, inexpensive fertilizer that keeps the soil productive

  3. Close, Intensive Planting – to maximize efficiency and productivity, to act as a living mulch, and to conserve water

  4. Companion Planting – to take advantage of the synergy between certain plants

  5. Carbon Farming – growing fertilizer while growing food

  6. Calorie Farming – growing the greatest number of calories per pound of food

  7. The Use of Open-Pollinated Seeds – to take advantage of seed saving

  8. A Whole-System Farming Method – using all aspects of the system to create a healthy, sustainable farm


CLOSE, INTENSIVE PLANTING is something that might seem counter to conventional wisdom. For instance, according to any seed packet you’ll read, tomatoes should be planted 18-36 inches apart with 4-6 feet between rows. Biointensive planting guides say, though, that if you can keep every plant 18-36” away from every other plant, you can have much narrower rows.