Do You Need a Cover For a Self-Watering Planter?

A planter box cover is a flat piece of plastic or fabric, often with elastic edges.  They are sometimes called “mulch covers”.  They fit snugly over the top of a planter and you cut holes to allow the plants to poke through.

When we got my first City Picker self-watering planter, we didn’t use a cover.  This year, with two new EarthBox planters, we decided to use covers, to see how they worked.  Now that the growing season is over, I wanted to share experiences on using planter boxes with and without a cover.

Cover Pros:

  • Warm or cool the soil
    • EarthBox covers are neat in this way.  One side of the cover is white, the other is black.  You can have the black side up in springtime, which will absorb more sunshine and warmth.  This is great for starting seeds early.  In summer, you keep the white side up and that reflects the sun, allowing plant roots to stay cooler in the hot sun.  The City Picker cover is black on both sides, I believe.
  • Reduce evaporation
    • If you live in a dry climate that doesn’t get much rain, this is a great feature.  The cover keeps more water in the soil and reservoir, by being a barrier to water loss from evaporation.
  • Retain soil and fertilizer
    • If you live in a windy climate, a cover can reduce soil loss.  Our general area is not windy, but since our balcony garden is up high, it does get a fair amount of wind.  At the end of a season, we might need to replace about 1” of soil in a box without a cover.

Cover Cons:

  • Repel rain water
    • Very little rain gets through an EarthBox plastic planter cover.  This was the biggest disadvantage for us.  We live in a temperate climate that gets rain at least once a week in summer.  After a rainfall, my uncovered planter boxes would get their reservoirs filled and soil soaked.  The covered boxes stayed dry, waiting for me to water.  The City Picker cover is fabric, so perhaps that may let some rain through.
  • Not beautiful
    • I found the covers to be kind of ugly, though that is a personal preference.  I couldn’t get past the feeling that I was looking at garbage bags on top of my planters.

The EarthBox literature says that other pros of the covers are that they deter insects from burrowing into the soil and reduce weeds.  I’m not sure I found these to be true for my planters.  There were enough holes in the cover (for the plants), that insects could easily get under.  Weeds were not an issue in any of my planter boxes either with or without covers.

The decision on whether or not you need a planter box cover comes down to personal preference and climate.  For example, if you live in a dry, windy, hot climate, then planter covers will make more sense.  If you live in an area where you get regular rainfall and don’t have wind issues, then covers are only optional.

For us, we will likely cover our planters in spring, to help seeds stay warm and get an early start.  But in summer, we’ll take off the covers so that rain can get in.  We may look into a more traditional mulch, like perhaps gravel or wood chips and will report back on those options.