How to Prepare an Edible Garden
Few areas of the garden benefit from detailed preparation like the edible garden. The two most important components are putting the infrastructure in place (beds and irrigation) and using healthy soil. Although this can take time and work, it's worth making the investment upfront so you can enjoy years of successful growing and harvests.
Build healthy soil
Whether you choose to plant in the ground or in raised beds or containers, soil is the key to success. The majority of edible plants grow best in loamy soils, a mixture of clay, sand, silt, and organic matter. Since Marin’s soil is predominately clay, it retains water and nutrients but needs to be amended for improved aeration, drainage, and replacing nutrients that have been used or leached out.
To grow edibles:
Start with healthy soil that has a pH between 5.5 and 7.5, depending on what different plants need:
- Acid soil (pH 5.5) – berries
- Alkaline soil (pH up to 7.5) – asparagus, beans
- Wide-ranging soil pH – carrots, cucumbers, garlic, parsley, peppers, pumpkins, strawberries, and tomatoes
Evaluate your soil
Simple tests for drainage, texture, pH, and the primary macronutrients – nitrogen, phosphorus, and potassium -- will help you determine what type of planting situation (in-ground or raised beds) would work best. Learn how to evaluate your soil.
Address soil nutrient problems
Edible plants provide clues when there is too much or too little of one or more of the six macronutrients. Here's how to recognize and address soil nutrient problems in the vegetable garden.
| HOW TO BUILD SOILS FOR EDIBLES 1. Start with compost: Add 1 to 2 inches of compost twice a year, for example in spring and fall, about two weeks before planting. This replaces nutrients, restores microbiological activity, and maintains soil health. 2. Test and add amendments as needed and according to directions on the product. Add amendments 1 to 2 weeks before planting. 3. Grow cover crops in winter and dig the plants into the soil in spring. 4. Add a layer of mulch in summer (leaves, rice straw, or another layer of compost) to retain moisture, minimize weeds, and provide habitat for soil organisms that positively affect plant health. 5. Add organic matter such as compost, leaves, and aged manure. 6. Consider sheet mulching (also known as sheet composting) – This is a process to eliminate lawns and weedy areas while building healthy soil. It is best started in the fall to prepare for a spring garden, but it can be done anytime. Within six months, the sheet-mulched area will have decomposed to about half its height and will be ready to plant. |
MAKE YOUR OWN SOIL MIX Soil mix for starting seeds Soil mix for containers Soil mix for in-ground and raised beds |
Follow these guidelines for beds and paths
To keep your garden accessible and well-organized, use these general guidelines when laying out your planting beds.
Width and length
• Keep beds a maximum 4 feet wide so you can access them from both sides.
• If accessible from only one side, limit to 2 to 3 feet wide.
• Beds/rows may be as long as space and irrigation system allows.
Depth
• Prepare beds to a minimum depth of 6 inches.
• 12 inches is better for drainage, aeration, and root development.
Orientation
• In large gardens there may be advantages for directional orientation of rows and beds, but this is not usually the case in smaller backyard settings.
• Orient planting beds to suit your personal preference and plant your tallest plants on the northern side.
Path width
• Keep paths minimum 2 to 3 feet wide to accommodate wheelbarrow, ease of movement, etc.
Care
• Don’t walk on garden beds or they will become compacted and not drain.
Decide on types of beds
In-ground raised beds and rows:
• Inexpensive way to create a healthy spot for growing your favorite fruits and vegetables
• Easier and less costly to construct than boxed raised beds
• Easier to turn over
• Offer growing spaces in gardens where boxes do not fit
• Build in-ground raised beds where there is at least one-foot of soil with no underground limitations
Boxed raised beds:
• Help with tunneling pests, poor drainage, poor soil, and underground rock
• Reduce the possibility of erosion by containing soil
• Warm up earlier in the spring
• Can be built to heights that limit bending
• Reduce soil compaction
• More expensive to build but are a more permanent option
• Some types of raised beds are portable
Containers:
• Easy and convenient
• No digging and the container may be placed right outside the kitchen door
• Terrific for patio gardens, accent plantings and for plants that may be invasive such as mint
• May be placed on wheels and if tall enough, may be wheelchair accessible
• Most any container made of a material that holds up well when wet and left outdoors will do
• Be creative and take a trip to a salvage yard or hardware store for inspiration
• Learn more about growing edibles in containers
Straw bales:
While most gardeners grow crops using soil or raised beds, it's possible to grow vegetables without soil using straw bales.
• Readily available material for soilless gardening that will provide compost as a byproduct
• Allow gardeners to avoid growing in poor soils or locations where plant diseases may already be present
• Requires additional water and fertilizer to prepare them for gardening
• Have been used as a growing medium for vegetables for at least half a century in Europe
• Learn more about growing edibles in straw bales
Clear and clean your planting site
Once you've selected and assessed your site, evaluated your soil, and know what type of beds you want, you're ready to get going.
• If you discovered any hazards or limitations above or below the site, (electrical wires, limbs, plumbing, rocks, high water table, easements etc.) begin by addressing these issues.
• If you are unsure of the location of underground utilities, check with your utility company.
• If your site is sloping, construct terraces or level planting boxes to minimize runoff and erosion.
• If your site includes ornamental vegetation that shades garden beds or competes for irrigation, consider removing it.
• If your site is covered in weeds, remove them when soil is damp and appropriately discard invasive weeds such as Bermuda grass, purslane, morning glory, and Scotch broom.
Construct planting beds
In-ground raised bed:
• Remove weeds when soil is damp but not wet
• Use a digging fork to loosen soil to a depth of 6 inches
• Spread 2 inches of compost on top
• Add other organic matter such as straw and dried leaves
• Evenly scatter amendments such as blood meal, kelp meal, rock phosphate etc., to adjust nutrients as indicated by soil test
• Alternatively, premix compost with amendments and spread the premixed blend over the raised bed
• With a shovel or digging fork, blend the compost and amendments into the bed to a depth of 6 inches
• Mound soil above the height of the ground into rows 30 to 36 inches wide
• Build rows 2 to 3 feet apart and do not step on the beds
Boxed above-ground raised beds solve many problems.
Boxed raised beds
• Often made of 2-inch by 6-inch or 2-inch by 12-inch preservative-free redwood or fir
• Boxes are made in a variety of sizes; multiples of 4 are efficient as they reflect the 8-foot standard length of lumber
• Reinforce corners with 4-inch by 4-inch wooden posts or metal corner brackets
• Install half-inch hardware cloth on the bottom to deter gophers
• Once in place, fill boxes with potting mix or amended local soil
Build an irrigation system for edibles
Irrigation systems in edible gardens need to be flexible because crop locations change from season to season and water requirements differ based on what's growing and whether plants are grown from seeds or starts. It's tedious and time-consuming to change drip emitter locations every season. Overhead or micro-sprayers are good for starting seeds, but not always a good choice for established plants such as tomatoes, which don't appreciate wet foliage. In addition, it is important that the gardener can easily amend beds without having to navigate around irrigation tubing, emitters, etc.
HOW TO BUILD A FLEXIBLE DRIP IRRIGATION SYSTEM for an edible garden bed: Follow these instructions to create an irrigation system that allows you to irrigate your edible crops with drip (for starts and established plants) or spray (for seeds). Because this system only connects to ONE point, it can be "lifted" to allow unimpeded access to the bed for amending soil. 1. Identify one point of connection (to water) for a garden bed. 2. Starting and ending at that one point of connection, build a perimeter 'loop" using 5/8-inch irrigation tubing. It should outline the bed and only be "connected" at the one place. 3. Run 1/4-inch or 5/8-inch emitter lines from one end of the perimeter tubing to the other, 6 to 8 inches apart. Be sure to tap into the perimeter line at both ends. This should allow you to plant anywhere in the bed and access drip irrigation. 4. Install adjustable micro-spray risers to the perimeter tubing so that it's possible to "spray" the entire bed if necessary OR turn one or more off when not needed. (This is helpful when starting seeds outdoors.) |
Rules of thumb for irrigating edible crops:
• Use a drip system if possible.
• Begin the season with a garden bed moist to a minimum of 12 inches deep.
• Check moisture content of soil with your finger several times per week.
• Water when the top 1 to 2 inches of soil is dry.
• Avoid wet/dry cycles and keep your garden consistently moist.
• Occasionally check 8 to 12 inches deep to ensure that the deeper soil is also moist.
• Irrigate early in the day.
• Observe plants for feedback. Yellowing of lower leaves provide evidence of over watering. Wilting and browning at edges indicates under-watering.
• When hand watering, apply water directly to the bed until the soil “shines” for 10-15 seconds.
• Plants need approximately 1 gallon of water per week in peak heat so if you are hand watering 3 times a week, apply about 1/3 of a gallon per plant per watering.
• Shallow rooted plants such as lettuce and other greens may require frequent shallow watering while plants with deeper roots, such as tomatoes, may be irrigated less often.
• Learn more about irrigation.
BACK TO EDIBLES
> What Edible Gardens Need
> Best Choices for Marin
> How to Prepare
> How to Plant
> Edibles in Containers
> Planting Calendar
> Grow & Care Sheets for Vegetables, Herbs & Fruits
> Tips & Techniques
> How to Maintain
> Fruit Trees
> Top 20 Edible Garden Problems
> Cover Crops & Soil Enhancements in the Off-season
> Conserving Water
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Visit our EDIBLE DEMO GARDEN at IVC Organic Farm & Garden
August 2024: Worms – The Architects of the Underworld
Worms create tunnels through the soil. These tunnels provide space for air and rain to more easily penetrate through the soil to the roots of plants. Just as we need oxygen to breathe, worms breathe oxygen that dissolves into their moist skin. Worms are long and thin so there is plenty of moist skin absorbing oxygen from air percolating the soil.
When soil is turned over any exposed worms quickly wriggle underground since exposure to light would dry out their skin and without moisture, they cannot access oxygen and will die. This is also why worms prefer moist damp soil. In a drought, worms burrow deep into the soil to find moisture. When it rains heavily saturating the ground, worms need to find shelter above ground, hiding under leaves or other debris so they don't dry out. This is why after it has rained hard, birds poke around in fallen leaves, tossing them this way and that as they hunt for tasty worms. You may not like to touch, let alone eat worms, but birds love them.
When we eat, our body absorbs nutrients as our food travels through our gut. Worms are the same. They also absorb nutrients from what they eat passing through their gut. A worm is like a long pipe with a central tube through it. Worms seek vegetable matter in the soil they ingest that travels through their lip as worms move, they take in soil through their lip into their esophagus. In their gizzard, the mix of soil and vegetable matter is ground up and mixed with enzymes releasing nutrients that are absorbed as food as it travels through their intestine. Just like us, not all the nutrients we eat are absorbed. The remaining nutrients in worm poop are ideal plant food for plants whose roots absorb them.
If you build a compost pile, remember just as you and I have favorite and disliked foods, so do worms. They dislike the citrus or onion families but love juicy fruits and chopped up green veggies. I once threw a few left-over radishes in my compost, only to discover months later, the same red radish as completely unblemished as the day I had discarded them.
Build Your Own Worm Bin
Raising your own vermicomposting worms can be an interesting hobby with earth-friendly gardening benefits. Learn how to create a habitat for worms at a hands-on workshop at Indian Valley College from 10 am to 12 pm on August 10, 2024. Look for “Build Your Own Worm Bin” listed under upcoming events on this website for more details and registration information.
Additional instructions can be found on the Marin Master Gardeners YouTube channel.
June 2024: Growing Edibles in Containers
In May, volunteers began planting edibles in 18 five-gallon square containers donated by the Indian Valley Organic Farm and Garden. The containers were drilled for irrigation lines and drainage, placed on wood pallets, and filled with compost and planting mix. Plants chosen for the new containers include peppers, tomatoes, tomatillo, eggplant, sage, thyme, dill, and Mexican tarragon. There will be an opportunity to compare the container grown plants with similar plants grown elsewhere in the garden.
What kinds of containers are best for growing edibles?
Do edible plants in containers need extra care?
Any vegetable or herb that can be grown in the ground or a raised bed can be grown successfully in a container, however the best choices are high yielding and dwarf varieties. A high-quality planting or potting mix should be used to fill the container. Avoid garden soil as it tends to become compacted and may contain soil borne diseases. More frequent watering may be necessary to keep the soil moist, but it shouldn’t become saturated. Frequent but light application of organic fertilizer helps to replace the nutrients that are leached out of the container. If the plants require some support, stakes or trellises should be installed at planting time to avoid disturbing the growing roots.
What are the advantages of growing plants in containers?
Another advantage of container grown plants is the ability to relocate them to the sunniest areas of the garden. Most annual edible plants require a minimum of six hours of sun a day. The ability to move plants around to take advantage of the best microclimates can extend the growing season for many vegetables and herbs. Containers can also be used to control plants such as mint, that like to spread to garden areas where they are not welcome.
Plants in containers are more accessible, making caring for them more convenient. There can also be fewer disease and pest problems. In addition, arrangements of healthy, growing plants in containers are visually pleasing and add interest and enjoyment to any location.
Click here for more information on growing edibles in containers.
April 2024: The Importance of Soil Testing
However, soil can look and feel healthy, and still be lacking nutrients essential for optimum plant growth. Plants suffering from malnutrition look unhealthy and show symptoms of deficiency. Growth may be stunted, leaves may be chlorotic (yellowed) or distorted, and shoots appear short and thin. Too little or too much of any one nutrient can cause problems. The best way to check for a lack of nutrients in the soil is to test a sample.
How are the nutrient components of soil tested?
Any soil test should start with a carefully collected soil sample. Use a stainless-steel trowel or shovel to obtain a sample at least six to eight inches below the soil surface. Avoid wet soil, if possible, the sample needs to be dry for testing. Taking samples from several places in a garden bed and mixing them can be useful in measuring overall chemical properties. However, samples from different garden areas (vegetable, perennial, lawn, etc.) should be kept separate. Soil testing laboratories generally provide specific instructions on sample collection.
Why does soil pH matter?
Nutritional elements in the soil need to be in a soluble chemical form to be absorbed by plant roots. There must be sufficient moisture in the soil to allow the roots to take up and transport the nutrients. The temperature of the soil also needs to fall within a certain range for uptake to occur. Finally, the solubility of the nutritional elements and the activity of the microorganisms responsible for the chemical transformation of nutrients are directly influenced by soil pH. An essential nutrient can be present in the soil, but not in a form the plant can use. Each nutrient has an ideal pH range for plant availability. At pH levels that are too acidic or alkaline, some nutrients can become insoluble and not accessible to plant roots. Phosphorus, calcium, and magnesium are elements that become less accessible as soil increases in acidity, while the availability of iron, zinc, and manganese is reduced in more alkaline soils. The ideal pH for most plants is between 5.5 and 7.5.
What nutrients are commonly lacking in soil?
For more information on assessing soil health, click here.
For hands-on practice in soil testing come to the workshop co-sponsored by the Edible Demo Garden and the Edibles Guild. Click here to register.
