Blog: How to Make a Container Garden Planter

February 8, 2019
Container Garden Planter

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I recently attended an interesting lecture on outdoor container gardening at The Boston Flower and Garden Show. I thought I’d post some of the tips on how to create a basic planter.

Whether you’re planting a container for outdoor flowers, vegetables, or herbs, the basic planter components can be the same. The trick is in the layering.

  • Start with the right container. For example, a hanging container covered in moss provides drainage and ventilation. The size and material of your container will depend on what type of plants you wish to grow. See the Almanac’s list of best containers for vegetables and best containers for flowers.
  • At the base of the container, add a reservoir to catch water. The reservoir can be as simple as a pie pan (or a Frisbee!).
  • Then, add shredded paper (e.g., newspaper). Fill up one-half to three-quarters of the space.
  • In the middle of the container, add a “slow-release” hard fertilizer (e.g., Osmicote) to provide the plant with food. It will last 3 to 4 months, usually into the middle of the gardening season.
    In midsummer, you’ll want to add liquid fertilizer. Cut the strength in half.
  • Also, add a polymer in the middle of the container to attract and hold water. A polymer typically hydrates for 7 to 8 years (well beyond the life span of most plants).
    Of course, you’ll want to check the moisture level in your containers every day. If the top 2 inches are dry, it’s time to water until it runs out of the bottom of the planter. It’s best to water in the morning.
  • As the top layer, add a mix of 80% peat moss and 20% perlite (or vermiculite). Do not use garden soil as it brings its own competition (other organisms, disease, etc.). Potting soil can work but is often too heavy.
    Peat moss is great because it holds moisture and provides air space. Perlite and vermiculite provide additional air space so that the mix isn’t too dense. You can buy the mix or mix it yourself.
    Most annuals have shallow root systems, so 4 to 8 inches of depth is ample.
  • Note: Although the basic peat moss and perlite mix should work fine for most flowers and mixed containers, there are a few plants that may need specialty mixes, namely orchids, succulents, and cacti.

Interplanting and Companion Planting

  • As you interplant, practice “companion planting” to get a good harvest. Mix plants that grow well together and often repel pesty insects yet attract beneficials.

    For example, plant tomatoes with parsley to attract beneficials (but not corn or broccoli).

    Plant cabbage with herbs, potatoes, and beans (but not strawberries or tomatoes).

    Plant lettuce with radishes or carrots (but not broccoli).

See the Almanac’s article on “Plant Companions: Friend or Foe?” for many more suggestions and a top 10 list of companions for common vegetables.

  • Flowers can also be planted with vegetables! For example, plant petunias with red chile peppers, ornamental grasses, and even herbs if you can squeeze them in. Cascading petunias are wonderful because they don’t require any pinching.
  • Some flowers are great for companion planting too. For example, marigolds are as good as gold when grown with just about any garden plant, repelling beetles, nematodes, and even animal pests.
  • As flowers die in the fall, add bulbs, put in a cold basement, and then bring out in the spring!

About This Blog

Your Old Farmer’s Almanac editors occasionally share our reflections, advice, and musings—and welcome your comments!