Raised Bed Gardening

For someone interested in getting into gardening this year, building a raised bed is a great option to consider. After completing this Do-It-Yourself project, a gardener has a contained area to grow annual vegetables, herbs, and flowers. The raised bed allows a gardener to control soil conditions, regulate watering, and control weeds - important factors for good garden results.

What should I grow in my raised bed?

Some vegetables that do very well in raised beds include tomatoes, peppers, cucumbers, summer squash, peas, beans, all types of greens, potatoes, onions, and garlic. In fact, if you start early enough in the spring it is possible in York County to get two vegetable crops from one raised bed. Early crops that can be planted in April and harvested in early July include onions, peas, greens, and other cold weather crops. These early crops can then be replaced with summer squash (yellow or zucchini), eggplant, cucumbers, or green beans, which will start fruiting in August.

Tomatoes and peppers are generally planted in May, begin fruiting in July, and will last well into September.

While herbs and flowering annuals will also thrive in raised beds one has to be cautious as they will self-seed in the beds. The trick here is to "dead head," or cut off dead flowers before they drop seeds. Some aromatic herbs to consider are basil, oregano, thyme, and rosemary, all of which do very well in York County summers.

While dill is also a nice pick for its savory green leaves, one needs to be careful to dead head as they are prolific seeders. There are many annual flowers to consider, but some favorites for their lively colors and long duration, are marigolds and zinnias

Where should I locate my raised bed?

Factors to consider with placement of your raised bed are full sun exposure, access to a watering hose, and having a location that is relaxing for you to sit back and watch your plants after you have taken care of them. Full sun is important for the vegetables as they need the sun's energy to thrive. Having easy access to a watering hose makes it more enjoyable to water the plants, as opposed to the alternative of using a watering can. If you are thinking of putting in more than one raised bed, make sure that they have at least three feet between them as a walkway.

A popular size for a raised bed is 4-feet wide by 8-feet long by one foot deep, total of 32 square feet of growing surface. This is deep enough for annual plant root systems and big enough to grow an abundant quantity. For instance, one of these 32 square foot raised beds can comfortably grow six to eight large tomato plants, enough to keep a household in tomatoes all summer. Some sources recommend a depth of 18-24 inches, which requires less watering and provides more room for root growth. This decreases drainage however and can increase the likelihood for rot. Use cedar wood if this is a concern and be prepared to reinforce the long sides of the bed, which may bow outward as the wet soil expands. In term of materials for this raised bed, here is a list of items needed to build the wood frame, add the underlayment, and fill it with topsoil:

1. The sides of the raised bed frame are made of six 2-inch by 6-inch by 8-foot- long pieces of untreated pine or fir lumber. If you are concerned about the bed rotting, cedar is more expensive but resists rotting. It should be normal household lumber and not be treated with any chemical preservatives as they will leach into your bed's soil. Each eight-foot side has two pieces of lumber running the full length and each end is made of one piece sawn in half, at four feet, two levels high.
2. To support each of the four corners, a 2-inch by 2-inch by 1-foot piece of lumber is placed on each of the inside corners. As an alternative, purchase four metal raised bed corners that are available from garden supply companies that also come with required screws.
3. To connect the side pieces at the corners, forty-eight 3-inch wood screws or deck screws are used, twelve on each corner. Butt the sides together at the corner and then place the corner post inside. Use the screws to affix all these pieces securely together. Connect the corners in the place you put the bed to align the sections with the contours of the ground. The plot does not need to be exactly flat with this approach.
4. As a weed and grass underlayment, either black fabric landscape cloth or plain brown cardboard can be used. Both prevent weeds and provide a water permeable layer for drainage. While black plastic sheeting provides a weed barrier, it is not water permeable and will cause root rot. Please do not use color printed cardboard as it may leach undesirable printing chemicals into the soil. Due to the use of the landscape fabric or plain brown cardboard underlayment, only limited digging, weeding, or soil preparation is needed.
5. Approximately thirty-two square feet of topsoil is needed to fill the raised bed. High priced potting soil is not necessary if you amend this topsoil with composted manure or compost. If you go the compost route, plan on adding about two to three inches on the top and mix it in with topsoil to get the organic matter and nutrients dispersed in your new raised bed. Filling the bed is satisfying as it completes the project but be ready for some bending and lifting.
6. Tools needed include a saw and a screwdriver to assemble the wood frame and a shovel to fill the bed.

This project, after getting the supplies, can be easily completed in an afternoon. It can be done any time of year but building one in early spring gives a whole season to grow in it. Let the newly filled raised bed soil settle for a few days before planting seeds or seedlings. After planting, you will likely check up on how things are growing nearly every day. With care and attention, you will have vegetables, herbs and/or flowers to share with friends and family. And you will have a raised bed to enjoy backyard gardening for many seasons to come.

Written by Andrew Morrison, Penn State Master Gardener of York County