Garden

The Comprehensive Guide to Raised Bed Gardening

There is nothing more tranquil than spending a day in the garden, surrounded by beautiful flowers, delicious fruits and vegetables, and butterflies frolicking about. It is the place we go to ease away stress and reconnect with our roots. Raised bed gardening is a method that allows us to spend more time enjoying our gardens and less time working to maintain them.

Raised bed gardens have been in use since medieval times and have gone by many names. The French are credited with creating the first “potager” gardens, which served as not only a source of food, but also as a feast for the eyes. These grand kitchen gardens were designed using geometric shapes and repeating patterns to provide both structure and accessibility.

During the renaissance, Louis XIV commissioned the most elaborate potager garden in existence for his palace at Versailles, known as “Potager du Roi Versailles.” The garden covered 25 acres and required 30 full time gardeners to manage its production. This set a trend that has endured for centuries. Check out the book Royal Gardens of the World for beautiful photos and layouts of the gardens at Versailles and other iconic places.

Benefits of Raised Bed Gardening

Raised bed gardens are renowned for their beauty but they also offer many functional benefits for both the plants and the gardener.

  1. Raised beds have superior soil structure when compared to field planting. They don’t suffer from compacting issues from being walked on, nor destruction of soil ecosystems through tilling.
  2. It’s easy to employ no-till methods for more nutrient rich soil such as mulch, compost, hügelkultur, companion planting, crop rotation and permaculture practices.
  3. Raised beds are the perfect solution when confronted with difficult planting sites containing poor soil, rocks, or uneven terrain.
  4. The high quality, undisturbed soil in raised beds allows for deeper plant roots and less root-crop damage from rocks, resulting in larger, healthier plants.
  5. Plants grown in a raised bed garden are easier to reach, this accessibility saves the gardener from repetitive, back breaking labor.
  6. Amazing weed control can be achieved with the use of mulch and weed-free pathways are easy to maintain.
  7. Improved drainage and soil composition prevents plants from being over or under watered.
  8. It is easy to rotate crops in raised beds from year to year which helps control soil borne diseases and pest insects.
  9. The elevated soil warms more quickly in spring which gives gardeners the ability to start planting sooner.

Site Selection

There are some key factors to consider when choosing a location for your raised bed garden.

Sun Mapping

One of the first things to assess is sunlight. Observe and map the path of shadows from trees, houses, fences, etc throughout the day, keeping in mind that these locations will change depending on the season. The sun is higher in the sky during summer and lower in the winter which changes the angle from which it casts shadows. Northern hemisphere growers should orient their gardens to the south to collect the most sunlight throughout the day (orient to the north for southern hemisphere growers). Most plants need at least 8 hours of sunlight a day to reach maturity.

Proximity

It is important to keep adjacencies in mind when planning a garden location. Raised beds are called kitchen gardens for a reason – they provide daily harvests for the dinner table. You may want to quickly step into the garden to grab some fresh herbs or veggies while you’re in the middle of cooking. For this reason, the garden should be located near the house.

Keeping the garden in close proximity to outdoor spaces you frequent often will ensure that garden chores such as weeding and watering are easy to complete. For example, if you spend time supervising your children while they play outside, locate your garden adjacent to their play area so you can pull a few weeds at the same time. If you visit your chicken coop twice a day, you could complete garden tasks as you walk past. Gardens that are far away or out of sight are more likely to become unruly.

Challenging Sites

Garden design can prove difficult when you have to overcome site limitations such as a slope or uneven grade, stumps or tree roots, and rocks or poor soil conditions. It is important to keep the top line of your raised beds as level as possible so that plant roots all get equal amounts of water.

Create a contour map to help you visualize the slopes of your site. Think of your raised beds more like retaining walls and create terraces that stair step down the slope, parallel to the contour lines. This will help capture the most amount of rainwater and prevent runoff.

Layout

When sketching out your initial design, try to include symmetry and repetition into your layout. Think of your garden as a work of art you will be enjoying for years to come. The human eye is attracted to patterns and orderly aesthetics. If you’re in need of inspiration, take a look at how I designed my raised bed garden in 2018. I have created a page in my Garden Planning and Design Tool specifically for this purpose. You can drag, drop, resize and customize shapes for both raised beds and garden plants to create your own layouts.

Walking Paths

Between your raised beds, you will need to plan on having walking paths. These should be 3-4′ wide whenever possible. There are many options to choose from for the turf of raised bed paths. Mowed grass is beautiful and helps retain moisture, but it requires constant upkeep and can look unkempt if it’s not mowed frequently. Other options include wood mulch, crushed gravel, pea stone, heavy duty landscaping fabric, low growing moss or groundcover plants, or hardscaping. Using a maintenance free material for your garden path will help suppress weeds and keep invasive plants from spreading into unwanted areas.

Irrigation

Plants grow bigger and healthier when they have a consistent water supply. Your raised bed design layout should take into account how each bed will receive its water supply. Sprinklers are a common watering solution and they can be used in combination with a timer so that you never forget to water your garden. There are many different styles on the market including telescoping tripods, oscillating, rotating, and linked sprinkler systems so you can find the right solution for your design.

Drip irrigation utilizes a system of hose tubing with small holes that allows water to drip slowly into the soil. This ensures no water is wasted and helps cut down on diseases caused by damp leaves and fruit. Similarly, water can be conserved with the use of wicking beds, which provide water to plants from an underground reservoir that is pulled to the surface by the plant roots.

Berms and swales are a permaculture technique for sloped sites that can create a passive watering system. After drawing a contour map as described above, determine a path you want water to flow through your beds and dig a shallow trench or “swale”. Your raised beds are the “berm” which will absorb the water and stop runoff. You could also incorporate a rain barrel to store rainwater from the roofs of buildings for later use.

Compost

The most important ingredient for healthy garden soil is compost. Consider integrating your compost system with your raised beds to cut down on labor and time. Weeds and pruning’s can be thrown directly into the compost which is much easier if it is nearby. Finished compost won’t need to be hauled long distances when you are ready to amend it into your raised beds.

Raised Bed Construction

At its simplest, a raised bed is nothing more than a mound of dirt. To create a raised bed without an edging material, dig a trench at least 3 inches deep around the perimeter of your bed to provide a barrier for weeds. Make sure this border has mulch with a depth of 3-6” inches. All the soil, roots, grass, etc from the trench can be turned upside-down and used to begin filling the raised bed. Then proceed to build up the interior of the bed as detailed in the next section “How to Fill Raised Beds”.

Size

Raised beds are typically between 6-18 inches in height, although you can go up to 24” if you desire. Having the ability to sit on the edge of the bed makes it easier to reach all your plants, so the 18” height is ideal for this purpose. (18” is standard seat height for most chairs and sofas.)

Raised beds should be no more than 3-4 feet in width, so that the center can be reached from either side. If the raised bed borders a fence, deck, house or barn, and can only be reached from one side, then 2-3 feet in width is better for accessibility. Length and shape of raised beds can be completely flexible, you don’t have to design using only squares and rectangles.

Wattle style raised bed

Materials

The possibilities are endless when it comes to building your beds. You can source free materials from neighbors or online marketplaces. Many of my raised beds are bordered by cement blocks that came from an old barn being torn down, they were posted as free for the labor of hauling them away. I’ve also used leftover composite decking and even whole logs from my woods carved into a “Lincoln log” design. Use your creativity, your raised beds don’t all have to match and you don’t have to spend a fortune to build the garden of your dreams.

The most important thing to remember is to use non-toxic materials. Never use treated lumber or anything that could leech chemicals into your soil. Any nutrients or chemical elements in your soil will be present in your produce. Healthy soil = healthy plants!

Some great materials to consider for edging your raised beds are: logs or milled wood, vinyl or composite wood, fabric, stones or rocks, cement blocks, woven wattle, pots or containers, galvanized metal, feed troughs, or even a living border such as a boxwood hedge. If desired, you can add a finish to your wood raised beds, tung oil is a great non-toxic option for use as a wood sealer.

Think outside the box – just make sure your materials are non-toxic

Containment

Plan to include some more contained areas in your garden design to control plants that tend to invade, spread or reseed. Plants such as mint will send out roots in every direction and are almost impossible to eradicate once they have become established. For plants such as this, use a pot, bucket, half barrel or something with a bottom that wont let the plant escape.

Some herbs such as dill, cilantro and borage will drop seeds and come back year after year so put these somewhere they wont become a nuisance. Other plants to keep contained would be strawberries, raspberries, oregano, Jerusalem artichokes, and some other perennials.

Square foot gardening is a great way to keep plants contained!

How to Fill Raised Beds

To understand how to fill raised beds, we have to have a basic understanding of soil ecosystems. Soil is full of insects, microorganisms and nutrients that are essential to plant health. Its important to preserve the structure of soil so that air, water and plant roots can easily move through. This means working your garden in a way that avoids tilling and compacting as much as possible. Raised beds are one of the best methods for this type of regenerative gardening.

Base Layer

It is not necessary to line your raised beds, because you want the roots of your plants to be able to access the ground deep beneath. Never use plastic or remove sod before filling your beds. You can cover the bottom of your raised beds with a natural material that will decompose such as cardboard, leaves or any raw materials you would add to compost. This will prevent any grass or turf from growing up to the surface without destroying the soil’s structure. It will also release nutrients for your garden plants as it breaks down.

Hügelkultur is a permaculture method that utilizes woody matter to greatly increase the fertility of raised beds. Line the bottom of your beds with logs and sticks that are dry/dead and won’t re-sprout. Avoid wood with high levels of toxicity, resin or rot-resistance such as black walnut, black cherry, pine, spruce or cedar. Over the years, the wood will attract worms and other beneficial insects to help it decompose, filling your beds with dense levels of nutrients.

Middle Layer

To fill the bulk of your raised beds, you can purchase compost or bags of garden soil from a local farm, garden store or landscape supply center. If you haven’t begun making your own compost at home, now is a great time to start so you can continue to feed your garden in future years.

Straw mulch

Top Layer

This is by far the most beneficial thing you can do for your plants, so please don’t skip this layer! Add a minimum 3″ of mulch on top of the soil to keep water from evaporating and prevent weeds from germinating. Trust me, this will make everything in your garden grow bigger and healthier while conserving water and labor. It also speeds germination time for seeds and greatly reduces transplant shock for greenhouse seedlings.

I prefer to use cedar wood chips because they take a long time to break down, but any other organic material will do. Other mulch options include straw, grass clippings/garden prunings, pine needles (these can increase soil acidity), coconut husks, cardboard, cocoa bean shells, or cover crops.

Cardboard strips are a great solution for keeping strawberry rows tidy

Soil will compact overtime as microorganisms continue to break down decaying organic material. It will appear as if your soil is shrinking down within the raised beds, this is referred to as settling. This is a completely natural and beneficial process, but it will be necessary to add additional compost and mulch as years go by.

Garden Design Extras

Now that we’ve covered the basics for designing and building a raised bed garden, it’s time to consider some beneficial add-ons to extend your growing season, protect crops and maximize space. It can be helpful to sketch out how you will layout the plants in your garden before determining where to put some of these garden extras.

Fencing

Nothing is more disappointing than putting in months of work tending your garden, just to have animals sneak in and demolish your produce. Consider putting a fence around your raised bed plot for universal protection. If this is not an option, you can place fencing or cages around individual beds. For more ideas on garden additions to keep animals away from your veggies, check out these Tips for Garden Critter Control.

Trellises

To save space, consider growing vining plants vertically on a trellis. Fences can double as trellises, just make sure you plant taller plants where they won’t shade the rest of your garden. Climbing vines include peas, pole beans, melons, cucumbers and squash.

Some other plants that grow tall and heavy with fruit can benefit from stakes, cages, string trellises, or other vertical support to keep them tidy and avoid soil borne diseases. These plants include tomatoes, peppers, tomatillos, eggplants, and raspberries. For DIY project ideas check out the book “Trellises, Planters & Raised Beds: 50 Easy, Unique, and Useful Projects You Can Make with Common Tools and Materials

Cold Frames

A cold frame is like a mini greenhouse that can protect plants from frost and extend the growing season. They are a wonderful idea if you live in a colder climate. Typically, cold frames are made of glass, polycarbonate panels or PE film just like you would find on a greenhouse.

If this doesn’t work with your design, individual plant cloches are an alternative option. Just be careful that there is good ventilation inside so your plants don’t wilt from too much humidity. When cold frames are closed, they don’t allow rain water to enter, so you will have to manually water the plants inside.

Flowers

The goal for most vegetable gardeners is to maximize growing space for edibles, however, making room for flowers could actually increase your harvests. Flowers attract pollinators and other beneficial insects to your garden which can increase the size of your produce. Flowers can also help accumulate nutrients in your garden soil and confuse pest insects by masking the scent and location of their target vegetables. Choose perennials with long bloom times so the bees always have a reason to visit your garden!

There are many varieties of edible flowers that can make wonderful additions to salads, herbal or medicinal tea, and other recipes. Some of my favorite edible garden powerhouse flowers are nasturtium, calendula/marigold, borage, viola/Johnny jump ups, and chamomile. Biodiversity should be a goal of any raised bed gardener.

Maintenance

Maintaining a large raised bed garden can be time consuming. To save on labor, plan to include perennials in your garden that will keep producing year after year with minimal labor on your part. I have put together an extensive list of perennial fruits, vegetables, grains, and herbs here. These plants can also help attract pollinators, deter pests and accumulate nutrients in the soil.

Soil Amendments

Many gardeners choose to add fertilizer to their growing plants. I however prefer to build the soil in my garden so that it has a natural balanced nutrient supply. If you do choose to fertilize, be sure to test your garden soil so you know exactly what to add. Use natural, organic fertilizers without harsh chemicals so that your produce is safe and healthy to eat. Compost or chopped up plant material (green manure) are both great natural fertilizers.

Pest Control

Insect pests can become troublesome as years go by in your garden. Rotate plants annually to confuse pests and take away their food supply. If insects persist, insecticidal soap and neem oil are both safe options to use in a food garden, just be careful not to hurt beneficial insects and pollinators in the process. For more options on dealing with insect crop damage, read The Gardener’s Guide to Pest Insects.

Weed Control

Weeding is of course the most dreaded chore of any gardener, but with a nice thick layer of mulch, you can keep weeds to a minimum. The best strategy is to pull weeds as soon as you see them sprout, before they have a chance to put down thick roots. Never allow weeds to flower and set seed or they will continue their life cycle with new seedlings.

If the entire garden has sprouted weeds due to a lack of maintenance, the best way to eliminate them is to fully complete weeding, one bed at a time so you can keep track of where you need to work. This systematic approach will have your garden weed free in no time and will keep you from feeling overwhelmed by the task ahead. To eliminate large areas that have been colonized by weeds, you can solarize the area with plastic sheeting. Solarization takes 4-6 weeks and uses the power of the sun to heat and kill weeds, bacteria and insects.

Growing

To get the most out of your raised bed garden, you can employ intensive gardening practices. Intercropping designs with companion plants saves space and allows fast growing crops to be interplanted between slower growing crops. Pair plants that don’t compete with one another for root space or light.

Succession planting is a tactic used to produce continuous harvests and ensure there are no empty spaces in your raised beds. When one plant is harvested, another takes it’s place. You can create a schedule for your succession planting dates or simply plant as empty spaces become available. Don’t forget to plan out how you will preserve and process all the wonderful produce you have grown so nothing goes to waste.

Save seeds from your heirloom, open-pollinated vegetables throughout the growing season to plant again next spring.

Preparing for the Next Season

You may be tempted to yank out all your finished plants by the root, but I must advise against this. These plant roots are part of the soil structure and are responsible for feeding insects and other soil organisms that, in turn, provide nutrients for future generations of plants.

Trim spent plants down to the ground and either add the green material to the compost pile or chop and spread it around your raised beds to act as “green manure”. It will decompose and enrich your soil. Never leave bare soil!

When your growing season has ended, it’s a great opportunity to test your soil to see if you need to make any amendments. When the garden is empty, you can add compost or manure, plant cover crops to overwinter or cover beds with additional mulch or fallen leaves to prevent new weeds from germinating.

Get Gardening!

Thank you so much for all the hard work you do making this earth a greener place! I hope this guide has given you both inspiration and confidence to grow more food this year. Please leave a comment with your personal raised bed gardening tips for other readers to enjoy!

The Comprehensive Guide to Raised Bed Gardening

5 thoughts on “The Comprehensive Guide to Raised Bed Gardening”

  1. Audrey, love this article and I have a perfect spot to create a raised garden! I can’t wait to do it next spring!

  2. I definitely agree that the most important ingredient for healthy garden soil is compost. There’s an easy and fast way to garden composting. Check out BierKashi. Also, I can’t wait to try raised bed gardening. Thank you for sharing!

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