Planters overflowing with annuals and perennials can soften the lines of your deck, helping to blend it with your yard. Make planters 18 to 24 inches deep if you’re planning to plant shrubs or bushes. Planters for annuals can be smaller. Line planters with waterproof material for longer planter life, and provide drainage in the bottom of the planter by using slats or plywood with holes bored in it. Always build planters with 1 to 2 inches of space beneath them to allow for air circulation.

Ornamental planters

Decks by their nature are intended to tie the indoors to the outdoors. Plants help reinforce that theme on any deck. Decks low enough that they don’t need a railing are particularly easy to build, but they can be a bit boring. Many low decks look as though they aren’t finished yet; they seem to call out for more attention. A border of flowers adds color, of course, but it also helps define and complete the structure.

Building a small planter

Build this planter from 2x8 or 2x10 pieces. Simply cut them to size and fasten the inside-corner 2x2s to the end pieces with 2-1/2-inch decking screws or 12d nails. Regardless of the style of planter, build it with feet or legs that allow air to circulate beneath it. Move the planter from time to time so moisture and mildew will not build up underneath it. Fasten cleats to the insides of the planters to hold a bottom shelf, which can actually be set at any height. Drill holes to provide drainage or use spaced 2x4s instead.

Building a planter for annuals or small perennials

Use leftover 5/4x6 decking for the sides of this planter. Cut four 24-inch pieces for inside the corners from scrap 2x2 baluster stock. Cut the decking to the lengths you want. Miter the corner joints for a professional look. Apply plastic sheeting or roofing felt on the decking material before attaching the 2x2s with leftover deck screws or 8d galvanized finishing nails. Allow the 2x2s to extend an inch or so below the bottom of the planter for air circulation. Drill drainage holes in the 1/2- or 3/4-inch plywood floor of the planter. Attach the floor to the cleats with 1-inch deck screws. Finally, a mitered cap rail of ripped 5/4x6 decking finishes off the planter.

Making a large planter

Most deck-building projects leave a small pile of 4x4 scraps lying around. Here’s a good way to put them to use. Use the scraps to provide vertical support for a planter, while doubling as a nailing surface for the side pieces. This technique is particularly useful for large planters; the finished size is limited only by the size of boards and posts in your scrap heap. Cut four 4x4s to the same length. Attach 2x scraps to the sides with 3-inch deck screws or 16d galvanized nails, lapping each board at the corner. Set the bottom boards about an inch above the bottom of the posts. Finish with a cap rail, mitered at each corner. Place this planter over a potted plant. Or enclose the bottom with plywood or board slats and add soil for shrubs and annuals. With the added weight of soil this planter may be too heavy to move so set it in place first, then fill it.