Container Gardening

May 13, 2011

Living in Fargo, North Dakota as a graduate student I grew hundreds of tomatoes to use for research purposes.  They grew in small pots and were mostly killed in the research conducted.  One lucky plant was hauled home in late fall, planted into a large pot (bucket) and placed in one of two small South facing windows.  It grew despite the very spartan conditions.  There were no insects to pollinate it but I would flick the flowers with my finger tips to move pollen.  The only light was from the window during the short days and the single incandescent bulb in the room.  That tomato never got very large or lush due to limited light, but did produce 23 tomatoes.  The tomatoes were about 1 ½ to 2 inches in diameter but otherwise were very normal tomatoes.  It kept producing tomatoes until the summer when garden produce became available. 

The tomato was grown as a curiosity to see how it would do in a small window. 

A few weeks ago a reader asked about vegetables in pots or small container gardens.

Try it!  You may be surprised at the success of plants.  Plants are like people, they want to grow and reproduce. Plants need only a few basic things for survival and good growth.  They are; a space for the plant to grow with support for the roots to attach to, to hold the plant, water, nutrients and sunlight.  Water, nutrients and sunlight have to be in the right amounts.  The nutrients and sunlight can actually vary quite a lot. 

The container can be just about anything.  The larger the container the more water and nutrients it will hold making life easier.  Pots, buckets, cans, wooden planters, and even a picture of an old boot showed up on the web as  a plant holder. 

Soil – Any good potting soil will be sufficient.  Potting soils are now engineered to hold extra water, provide nutrients for an extended period of time and support the plant via a good mixture of organic materials for the roots to spread out and to grow in.  Hydroponic plants can be grown in soil less environments.  Tubes filled with rocks are used and provide a place for the roots to grow and to anchor the plant.  Water and nutrients are pulsed down the tube at regular intervals so the roots can have what they need.

Most people simply buy a potting soil.  Which is best?  My local greenhouse owner “Little Red” makes his own potting mix, and of course it is the best.  My guess is it is very good but none of you can buy it unless you come to my town.  Major brands are Espoma, Fafard, and the family of products from The Scotts Company, Hyponex, Miracle Gro, Osmocote and Organic Choice garden soils and potting mixes.  My guess is they are probably all good.  Some have a total organic mix or a brand of fertilizer added to differentiate them.  For my graduate research we used 1 part soil, 1 part manure and 1 part decomposing tree bark all mixed in a grinder.  Today’s mixes mostly contain bark, peat moss and some contain a new ingredient coconut coir.  Coconut coir is the fiber from the coconut husks.  Is it a better ingredient in soil mixes?  It works and has good water holding capacity.  But so do the other organic components.  Some claims for holding water are made by adding water absorbing gels that hold lots of water and slowly give it up as the soil dries.

Water – Plants need the right amount of water.  Most plants in pots are overwatered.  Roots need to have oxygen which they get from air spaces in soils.  Overwatering fills those air spaces depriving the plant of oxygen and promoting root diseases such as pythium and phytopthora.  Only water when the soil is dry but before the plant wilts and drops leaves.  Choosing a larger pot helps keep the right amount of water for the plants.  It also makes it so you don’t have to water as frequently.  Provide a pot with holes in the bottom so excess water can drain is not essential but is a great point of success. 

Nutrients - A good soil, including most potting soils come with enough nutrients to provide those needed for several months.  If the plant becomes very large or has been supporting plants for several months, or years, you need to add nutrients.  A good water soluble fertilizer like Green Light’s Super Bloom mixed as directed and applied every two weeks will help the plant continue to thrive. Another fertilizer method is an application of Osmocote every few months to ensure good fertility.  Over fertilizing will cause a build up of nutrients to create a salty soil condition.  When soils become salty the salt holds the water not allowing water to be absorbed by the plant.

Sunlight – The right amount of light is critical and varies from one plant to another.  Most plants need a minimum of 8 hours of sun with 12 to 16 hours being ideal.  My garden gets a maximum of 10 hours of direct sun with some tree shade mixed in.  Direct sun is much better than filtered sun or other ambient light.  A few plants like ginseng, impatiens and azaleas do well with less light in shady locations. Tomatoes will grow with less light but will thrive and produce much better with direct sunlight for more than 12 hours a day.

Recently there have been several commercial variations of plants in pots.  “Square Foot Gardening,” “Topsy Turvy,” and “Potatoes in a barrel,” are examples.  They work but any container large enough to maintain the size of plant will work just as well.  Hanging baskets do very well, except many are hung in the shade so they are limited to shade loving plants.  Just get something to hold the plant, get some soil, and try the plants you want.  Follow the principles above and you will be successful.

The number one vegetable is tomatoes and they do well in pots and provide great rewards.