Raised bed gardening is a method that uses a variety of materials to frame an area, elevating the garden soil from 6 - 36” above the surrounding soil. Raised beds tend to be more productive and easier to manage. One exciting new example of raised beds is keyhole gardens.
Benefits of raised bed gardening
Raised beds in the garden make it easier to control soil structure, irrigation, and pests. Raised beds also allow you to plant earlier because the soil warms up more quickly. Generally, plants in raised beds are planted more closely together, creating a beneficial microclimate that suppresses weed growth and retains moisture. Since gardeners do not walk on raised beds, soil compaction is avoided, and they make reaching plants (and weeds) much easier! Raised beds are an excellent choice in limited spaces, or if you are a renter and not allowed to alter the landscape. Another added benefit of using raised beds is that it is very easy to add trellising, row covers and protective wire to keep birds away from seedlings.
How to build raised beds
Raised beds can be practically any size or shape. A raised bed can be nothing more than a walled area on the ground or it can be an elaborate artistic structure that showcases garden gems, or anything in between! You can see an excellent sampling of different types of raised beds at instructables.com. The steps below can help you get started creating your very own raised bed.
1. Select a location
2. Select building materials
3. Clear the area
4. Measure twice, cut once
5. Add soil
Plants for raised bed gardening
Raised beds are a great tool for productive foodscaping, since the root systems of most vegetable crops are relatively shallow. If your raised bed is on the ground, however, it won’t matter. Even the worst soil is bound to improve over time, with a raised bed above it, to allow deeper-rooted plants to perform well. If ground squirrels and voles are a problem in your area, attached hardware cloth, not chicken wire, to the bottom of your raised bed. This will protect your plants' roots.
The first rule of vegetable gardening is to plant what you will actually use. Check out this excellent vegetable planting chart to see what to plant and when (in California).
Keyhole gardening is a method developed for areas experiencing severe drought and limited resources, specifically Africa. However, the concept is just as useful in other parts of the world and in your backyard. Keyhole gardens conserve water, and they provide plants with easy access to nutrients.
Keyhole gardens are a variation on raised bed gardening. Keyhole gardens are round raised beds that feature a notch in one side that provides access to a composting tower, or basket, in the middle. As compostable materials and water are added to the center of a keyhole garden, the water and nutrients spread out within the keyhole garden to feed and irrigate your plants. The loose, nutrient-rich soil makes it easy to grow edibles in even the worst conditions.
How to build a keyhole garden
Keyhole gardens are easily made with curb-scored old bricks, stones, or cinderblocks. You can also use landscape cloth, wood planks or branches, wine bottles, old fencing panels, corrugated metal sheets - really, you can use anything that isn’t toxic. Use your imagination! Follow these steps to create your very own keyhole garden:
Sources of compostable materials
Most people know that yard and kitchen waste are compostable, but there are many other sources of perfectly acceptable materials for the basket of your keyhole garden or any compost pile. Remember that compostables are designated as “browns” or “greens” and that you should aim for a 50:50 mix of the two. Some interesting source of “green” compostables include coffee grounds and tea bags, often available for free from coffee shops, and fresh manure from local barns. [Manure from veterinary clinics is not recommended.] We throw away a profound amount of compostable “brown” material. Some sources you may not have considered include any paper or wood products (simply avoid the colored, slick, or waxed varieties), dryer lint, vacuum cleaner waste, unwaxed cardboard, and even clothing made from 100% natural fibers. Rather than adding these materials to local landfills, you can transform them into plant or worm food in your compost pile, worm farm, or in the central basket of your keyhole garden.
You can grow a surprising amount of food in your own yard. Ask me how!