How to Build a Raised Pollinator Garden Bed

by joe owczarski

A bed frame for a raised pollinator garden, can be as simple as 2 x 4s on top of the ground, or even patio retaining wall blocks. The size is up to you. A bed that's at least 6 inches high provides ease of access and gives roots plenty of room to grow. Untreated lumber isn't rot-resistant, but it's a good option for edibles.

The wood to use for a raised bed is your decision. Cedar and redwood are naturally water-resistant but can be expensive and hard to find. Hemlock, fir and pine are suitable materials for raised beds but aren't very long-lasting. Pressure treated lumber is an option. Pressure treated lumber has been a controversial topic for many years. The purpose for chemical pressure treatment is to protect wood from rot, decay and wood-ingesting insects. Current treatments such as alkaline copper quaternary (ACQ) are deemed low-risk by the EPA and designated safe for use around humans, pets, plants and vegetables. Creosote-treated wood is not a good option for vegetable raised beds. Compared to untreated wood, pressure treated lumber lasts longer and is available at a comparable cost. Some types are specifically treated for ground contact.

There are numerous ways to create your own pollinator garden that can fit the style of your home. In fact, they can be built using some basic materials that you may already have in your home.

Step 1 - Select the bed location

If you are building a raised bed, pick the best possible place for the 4’x8’ raised bed (instructions below). Ideally the front (the long piece of wood) faces the southern sky. The plants in this pollinator garden design require as much sun as possible, so look for a place out in the open. You will also want to try and be close to a watering source, so you don’t have to haul water to the bed or hook hoses together to water the plants while establishing their first year.

Step 2 – Prepare the Area

Soil (Three options)

  1. Best Option: Miracle Grow Natures’ Care Organic Raised Bed Soil 1.5 cu ft. bag = 22 bags OR
  2. Second Option: Miracle Grow Garden Soil for Flowers & Vegetables .75 cu ft. bag = 44 bags OR
  3. Third Option: Topsoil 1 cu ft. bags = 18 bags AND Composted Cow Manure 50 lb bag = 20 bags

Mulch

2 cu ft of any mulch will do.

Other/Tools

Tiller Planting Diagram

Shovel Potted Plants Garden Fork Trowels

Tarp (optional) Watering Hose

Wheelbarrow (optional)

Step by Step:

  1. Prepare the soil. The soil where you plan to build the bed needs to be either tilled, or double dug with a shovel. If you till, it needs to be tilled to a depth of about 18-24”. If you encounter any rocks, roots, or other debris while tilling, please move those to another area. If you do not have a tiller, you will need to double dig with a shovel. Dig the top layer of the soil off, down to the level of your shovel. You will need to place this soil to the side -in a wheelbarrow, or on a tarp for safekeeping. You will need to dig a trench the length of your bed. After digging all of this soil out, you will take a garden fork, and break up the soil the depth of the fork the length of that trench. This is not easy as the soil is often very compacted, and you will need to work very hard to really loosen the soil. The more work you put in on the soil, the better your garden will look down the road. Once you have loosened the bottom part of the trench, you will begin again on the top of the soil next to this trench with your shovel and put the soil you remove in the first trench. When you get down to the level of your shovel, you will loosen the soil with your garden fork again. Repeat this process until you work across the entire width of the bed and then finish by putting the soil from your first trench into the last one.
  2. Plants can be placed in the ground or in a raised bed. If choosing the raised bed option, place the constructed raised bed structure over the area that you have prepared and dig in the corner posts.
  3. Add the soil. Now you will add your bags of soil and mix them into the soil below with your shovel. When mixing is complete, use a rake or shovel to spread the soil evenly across the length and width of the bed.
  4. Position the plants. Arrange your plants according to the planting diagram provided.
  5. Dig holes for the plants. Dig a hole that is approximately the size of the pot.
  6. Plant carefully. Take the plants carefully out of the pots. If any of the plants appear to be pot-bound, gently loosen the roots before placing the plant into the hole. Make sure that the crown of the plant, that is, where the plant stem meets the roots, is about 1” above the soil line when you place it in the ground. Gently pack the dirt around the plant.
  7. Mulch the bed. After all of the plants are in the ground, mulch the bed thoroughly, to a depth of at least 2”.
  8. Water the bed. Water the bed thoroughly, until the soil is saturated to a depth of 2”.

To build the garden bed, follow these instructions below:

Materials

  • Four 16-inch-long pressure-treated 4-by-4s, to act as corner posts
  • Two 4-foot-long pressure-treated 2-by-12s, for bed ends
  • Two 8-foot-long pressure-treated 2-by-12s, for bed sides
  • Twenty-four 3.5-inch #10 flat-head wood deck screws

Tools

  • Drill
  • 1/8-inch drill bit & screwdriver bit
  • Table saw (if lumber is not pre-cut to size specifications)
  • Ruler and pencil
  • Level (optional)
  • 4 adjustable woodworking bar clamps: 2 short (12 -inches) and 2 long (6-foot) (optional)

Step-by-Step

  1. Frame

The bed will be built upside down. Working on a flat surface (such as a patio), set a 4-foot 2-by-12 board on its narrow side edge on the pavement; at one end of the board, place a 16-inch 4-by-4 corner post upright and flush with the end of the board. Use two adjustable woodworking clamps—or a buddy—to keep both pieces of wood flush on the sides and bottom.

  1. Drill to attach

Before securing the post to the 4-foot board, help prevent the wood from splitting by pre-drilling three evenly spaced holes in the board with the 1/8” drill bit. Then, secure the board to the post with three, 3.5” screws. (Once the board is secured to the post, the woodworking clamps can be removed if they are being used.)

  1. Repeat to complete

Now that the previous step’s post-adding techniques are mastered, repeat those techniques to attach a corner post to the other end of the 4-foot board. Repeat this technique to add the remaining 4-foot board and attach a corner post to each end.

The two 4-foot ends of the raised bed are now completed, and it is time to attach the bed’s longer sides: Position the first of the 8-foot 2-by-12 side boards between the two 4-foot bed ends. Make sure the 8-foot board is flush with each corner post (hold them steady with the woodworking clamps—or grab that buddy again), and then pre-drill each board end with three holes and secure it to a post with three, 3.5” screws. Repeat to attach the remaining 8-foot side board to the awaiting corner posts.

The rectangular bed is now complete!

  1. Anchor the bed

Once the bed location is decided upon, dig a 5- to 6-inch-deep hole for each of the corner posts. Then sink each post into the ground.

  1. Level the bed

Make sure the bed is level on all sides (using a level if you have one); this will ensure that when watering the water will spread evenly through the soil. Then backfill the corner holes with dirt to steady the posts.

Follow these guidelines and safety precautions anytime you use pressure treated lumber:

Guidelines

  • Use fasteners and hardware labeled for treated lumber — stainless-steel or hot-dipped, galvanized screws.
  • Butt lumber tightly. Pressure treated wood shrinks as it dries.
  • Drill pilot holes to prevent splitting when nailing or screwing boards.
  • Use wood rated for ground contact when necessary for the project.
  • Let the wood dry before use. It can take six months or longer for treated lumber to dry. You can then use as-is or paint or seal it.
  • Line the interior sides of the bed with sheet plastic or pond liner.
  • Plant edibles nearer the center of the bed, a few inches away from the wood.

Safety

  • Wear gloves, a dust mask and eye protection when handling or cutting wood.
  • Wash your hands after working with treated wood.
  • Dispose of sawdust and waste according to local regulations.
  • Don't burn pressure treated wood.
  • Don't use pressure treated wood as mulch.

Below is a list of pollinator-preferred plants:

Size Plant Botanical name Note
S Sweet alyssum Lobularia maritima Often sold in multi-packs; easy to start from seed
S Nasturtium Tropaeolum majus If you want them to spill over the edge, look for "trailing" or "climbing" varieties. Easy to start from seed.
S Annual phlox Phlox drummondii Look for the Intensia series
M Calendula Calendula officinalis Single-petal forms—instead of doubles—are more attractive to butteflies.
M Sweet William Dianthus barbatus You can often find plants in multi-packs at the garden center.
M Signet marigold Tagetes tenufolia An uncommon variety; easy to start from seed. Look for Lemon Gem.
M Pincushion flower Scabiosa columbaria
M Zinnia Zinnia Look for shorter varieties, such as the Profusion series.
M Borage Borago officinalis Very easy to start from seed
M Bee balm Monarda fistulosa Native to many areas of the U.S.
M Flowering tobacco Nicotiana alata
M Salvia Salvia coccinea Coral Nymph is lovely and floriferous.
M Cuphea Cuphea Available in 4-inch pots at garden centers; I like Flamenco Samba
M Blanket flower Gaillardia pulchella Native
M Gomphrena Gomphrena haageana
M Pentas Pentas Often sold as a houseplant, in 4-inch pots
M Marguerite daisy Argyranthemum Look for it with the annuals, in 6- to 8-inch pots.
M Gaura, whirling butterflies Gaura lindheimeri A perennial that blooms like an annual — almost all summer
T Four-o-Clocks Mirabilis jalapa An old-fashioned classic
T Hyssop Agastache rupestris Anise-scented foliage
T Butterfly flower, butterfly weed Asclepias Choose a species that's native in your area.
T Fennel Foeniculum vulgare
T Cosmos Cosmos bipinnatus Look for shorter, "knee-high" varieties
CL Cardinal vine Ipomoea x multifida Easy to start from seed
CL Firecracker vine Ipomoea lobata Easy to start from seed
CL Passionflower Passiflora caeruela Often sold in larger pots (1 qt. or more)
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