Think of raised beds as super large container gardens. Raised beds are often used by gardeners when their soil is less than perfect--and let’s face it, most soil is far from perfect. If there is too much sand, for example, water will go through too fast and leave the plants thirsty. Many soils are rocky, making it difficult for plants to send down roots. Building your own garden box on top of the ground allows you to get better results than you would otherwise.
You can have the soil you want, not the soil you are stuck with.
Because they lift plants up, raised beds also help people access the plants more easily for weeding, watering and harvest and put less stress on joints and are kinder to backs.
What Can Be Grown in a Raised Bed?
The good news is that there are many plants--and almost all vegetables-- will work well in a raised bed. They are commonly used for growing fruits, vegetables, herbs and flowers. If you are growing root vegetables, you may want to dig down deeper to make sure there is enough loose soil for roots to properly form. Efficient methods like square foot gardening can be used to maximize production and are easy to lay out in a grid system within the box.
Types of Construction Materials
There are a variety of options available if you want to create a raised bed. Wood planks are a common choice. Make sure that chemicals have not been used to treat them, as these can leach into the soil and into your vegetables, fruits and herbs.
For this reason, if you are going to re-use found wood or pallets, source them carefully as in many cases, they have toxins and/or pesticides present in the wood. Choose fastening materials like bolts or screws that are made of a substance that will not rust, like stainless steel.
Cinder blocks are another possible option for your raised bed.
They will last almost indefinitely and weather better than wood. If you lay the concrete blocks so that the holes are facing up, the sides will create a solid wall. Use rebar inside each opening to keep the blocks from shifting. Plants that stay on the smaller side (some herbs, onions, radishes, etc.) can even be grown in the holes. Watch on your local classifieds, Freecycle and Facebook yard sale groups as they are sometimes offered for free if you haul them away.
If your garden is naturally rocky, use that to your advantage by building your raised bed for free with those stones. These are also a common item given away on classified groups if you are willing to pick them up.
Another great option is to buy a raised bed made of fabric. One of the advantages of a fabric bed is that at the end of the season, you can dump out the soil, wash off the fabric, fold it up and store it for the winter. You can even make a raised bed from a kiddie pool.
A raised bed is your opportunity to compensate for natural soil that is too sandy, full of rocks, poor in nutrients or otherwise problematic for your plants. The simplest method would be to buy bags of potting mix to fill the box. Depending on the type and brand you choose, as well as the height of your raised bed, this can turn out to be very expensive.
You can mix up your own potting soil using equal parts of materials like topsoil, peat moss and compost. Adding perlite or vermiculite is helpful to stop the soil from becoming compacted and make it easier for water and nutrients to flow through. Place your materials into a compost tumbler or large wheelbarrow and mix them together. Use this opportunity to add in organic, slow release fertilizer, following the directions for amounts. You can also to add aged manure or compost instead of fertilizer.
If you do not make your own compost, call your local waste management and recycling facilities. In some cities, green waste is collected and turned into composts and mulches that are usually priced competitively. They may deliver for a fee, but you can also use a pickup truck to transport it yourself.
When you are planning out your garden, it is tempting to maximize space by creating one large raised bed. However, it will work much better if you break it up into several boxes. If the bed is too wide, it will be very difficult to reach across to thin seedlings, keep weeds down and harvest your crops. You want to keep the width a maximum of four feet wide.
If you are working with an area that is not flat, remove soil or build up areas so that your planting area will be even. Smooth it out before adding your soil mixture to the container.
Filling your raised bed is also something to think about when you are planning. These boxes offer the opportunity to use potting soil or other mediums that mean you can still garden when your soil is poor. However, the cost can really start to add up when your box is bigger. However, if you want to grow deeper rooted plants you may want to start with a 12" height.
If you are designing it for someone with illnesses or disabilities, make sure that the pathways are wide enough to accommodate assistive devices like wheelchairs and walkers. Allow space to go around corners and exit successfully. Make the sides two feet high to make it accessible for the gardener to reach towards the plants from a seated position. Wider pathways will also mean that wheelbarrows can be used in the area.
Watering Your Raised Beds
The optimal time to water is in the early morning. Containers like raised beds tend to dry out faster if they are watered during the middle of the day since hot temperatures in summer speed up evaporation. Watering at night can be problematic in some areas, though, since the plants are wetter for longer in cool temperatures and fungal diseases have an easier time becoming established. Morning irrigation allows for the most moisture to reach the plants, but still gives them time to dry off enough to avoid fungi.
Options for irrigation include your garden hose, sprinklers or drip irrigation. A hose allows you to directly water each plant and control how much they get, but requires your presence for each session.
Sprinklers can be set on a timer, but they spray over a general area. Some plants may be missed, while others are drowned.
Drip irrigation is a great way to provide water to the plants in your raised bed. This method allows you to directly deliver moisture to each plant through a system of hoses, tubes and emitters. You can customize the amount that each one gets and make sure that water is not wasted. Test it out at the start of each season to look for clogs in the tubing and emitters and replace as needed.