Homegrown: Container gardening

Linn County Master Gardener, Lisa Slattery, provided the following information about container gardening:

 One of my favorite gardening tasks is to plan and plant my containers for the growing season.  I start off with pansies as soon as I can in the spring and transition to warmer weather annuals and foliage once all frost is gone.  I add containers into my gardens, but containers are perfect for people without time and space for a traditional garden.  Plus container plantings can be moved around. They add color, beauty and grace to walkways, porches, patios and decks.

There are a few keys to successful containers. First choose a container that fits your space - think window box, hanging basket, wall-mounted pots, and classic terra cotta clay pots. If your container doesn't have drainage, drill four ¾ inch diameter holes in the bottom. To help fill up space in large containers, place plastic packaging “peanuts” in the bottom, cut to fit a layer of porous landscape fabric (to help separate soil and “peanuts” for clean-up) and top with good potting soil. Don't use garden soil since it will compact in containers. Choose a commercial potting soil or make your own with equal amounts of soil, sphagnum peat moss and perlite.

Place the tallest plants in the center or back with shorter plants and trailing plants around the edges. You've heard the saying – a thriller, filler and a spiller? Make sure you set the plants at the same depth they were already growing in the cell-pack or pot.  Choose plants that share the same light requirements, sun loving plants for containers on hot cement walkways and shade lovers for pots under trees. 

After planting always water thoroughly.  Just like light requirements, you'll want to make sure you don't mix water hogs with plants that like dry soil.  For example impatiens like moist soil and petunias likes dryer soil.  Your watering schedule will depend on the container size and placement.  All containers should be checked daily. 

Containers require regular fertilization.  Soluble fertilizers can be applied weekly at ¼ the recommended monthly rate or you can opt for slow release fertilizers which release a small amount of fertilizer every time the plant is watered.  Check labels for application rates.  

Maintain your containers by removing dried leaves and spent blooms regularly.  Petunias or other leggy annuals need to be pruned mid-summer.  Cut back stems to about four to six inches to promote branching out and more blooms.  As for petunia's look for new varieties on the market that don' need deadheading anymore. 

So, thriller, filler, spiller, right?  What to plant?  Choose plants and colors that you like, keeping in mind like light and water requirements.  Think about mixing flowers and foliage, upright growers and trailing plants.  For a nice list of recommended annuals for containers visit the ISU extension website at

http://www.extension.iastate.edu/Publications/RG301.pdf  and as always, happy planting!