If the children are tired of building boats and castles out of shipping boxes, let them build gardening containers.

We all know and love the advantages of container gardening. It offers a way for those living in small spaces to grow colorful flowers and fresh vegetables. We also know that the cost of planters and flowerpots can be quite high, especially if you want to grow more than two or three plants. Remember back in grade school when we used aluminum cans and milk cartons to grow seedlings? We knew, even back then, that it isn’t about how a planter looks, but how it performs. If you have a number of shipping boxes at your house, whether from a recent move, online shopping, or monthly fashion subscription services, you already have the perfect planter for growing edible plants in a container. The rectangular shape of sturdy cardboard boxes makes them easy to arrange in a yard or on a patio, and the cardboard can be recycled at the end of the season. If you are looking for an easy gardening project to do with your children, teach them how to turn cardboard boxes into garden planters.

Prepare the Box

Choose a box with the width and depth needed for what you want to plant - check your seed packet or plant tag for exact requirements. Radishes, for instance, don’t need as much depth as potatoes. Choose a sturdy, corrugated cardboard box rather than thin cardboard like a cereal box. If a box has been wet or has torn sides, send it to the compost pile and find another.

Turn the box over and reinforce the bottom with one or two strips of duct tape (or a similar strong tape) applied across the seam where the flaps meet. Apply tape to any weak corners on the box as well. Fold all the flaps down outside the box and tape them down. Not only does this hold the flaps in place, it also helps to strengthen the outer walls of the planter. To make your new gardening container more attractive, you can paint it, add stickers, or simply tie colorful ribbons around it.

Use a punch tool or large screwdriver to poke several holes, spaced about 4 inches apart, in the bottom of the box for drainage. If you wish, you can also line the box with a plastic bag to keep the box dry and extend its life, just remember to also poke drainage holes through the bag and out the bottom of the box.

Choose the Right Spot

Set the box in the spot where you want to grow the plants before adding the potting soil. Follow the sunlight needs for the type of plant you wish to grow to determine the best placement. Most vegetable crops, for example, require full sun or a minimum of six hours of direct sunlight. This is the final location for the plant, because the cardboard will soften and become difficult to move later in the season. If you have filled your cardboard planter with kitchen herbs and plan to keep it on the patio or deck, it is a good idea to elevate the box – set it on bricks or slats - so that when the water drains out of the box it doesn’t just pool around the sides.

Add Soil, Seeds, and Water

Fill the box with lightweight potting soil to within 1 to 2 inches of the top. Tap the box to settle the soil. Plant seeds or seedlings in the box according to the package directions and follow the plant spacing advice on the package to decide how many plants to place in each box.

Water the plants in your new garden to keep the soil evenly moist; follow watering guidelines for the specific plant you choose. Though cardboard gets wet when you water the soil, the porous, fibrous material dries out quickly, so you might need to water more frequently than with plastic and ceramic containers.

If the original box starts to break down before the end of the growing season, try to slip it into a new, larger box for extra protection – just remember to poke drainage holes in the new box. If possible, you can even move the plant to a permanent spot in the ground.