Daniel Gill, Merrill, Thomas A.
By Dan Gill
LSU AgCenter Horticulturist
Humans have a long history of growing plants in containers. That history goes back thousands of years, and the popularity of growing plants in containers continues today for many reasons.
In-ground beds are not always available where you would like to grow plants. That’s the case with paved courtyards, decks, apartment balconies and patios.
Flexibility and change also are two outstanding features of container-grown plants. Landscapes may be altered quickly by changing the arrangement or location of containers or the plants growing in them.
In addition, growing specimen plants in attractive containers at the entrance, on the terrace, along entrance walks or paths or at other strategic places in a landscape setting is one means of enriching the landscape and adding focal points.
Nearly any plant may be grown in a container as long as you provide the cultural requirements the plant needs. Even commonplace plants take on a distinctive quality when grown in a container. You can choose from small-growing evergreen or deciduous trees, shrubs, ground covers, herbaceous perennials and annuals.
When selecting the plants, first decide where the plants will be used. The amount of available light is the most important factor to take into consideration. Whether the location is sunny or shady, you must choose plants that will thrive in those conditions.
The hardiness of large specimen plants in big containers also can be an important factor. Generally, choose hardy plants that can survive winters outside, so that you won’t have to lug large, heavy plants and containers into protected locations when a freeze threatens.
A variety of manufactured containers and found objects can be used for container plantings. These, of course, vary in size, material, color, shape and design.
Only your imagination and taste set the limits, but generally try to use those that are muted colors and simple in design, since brightly colored and heavily decorated pots will detract from the plantings. There may be certain settings, however, where you feel more elaborately decorated containers are appropriate.
When selecting containers, choose larger sizes, if possible. Small containers are out of scale with outdoor landscapes and require more frequent watering.
Also make sure the containers you use have one or more drainage holes in the bottom to allow excess water to drain out of the pot when you water. This is critically important. Although it is not impossible to grow a plant in a container without drainage holes, there is the constant possibility that the plant’s roots will drown if you apply too much water at any one time
More than anything else, the soil or potting mix used in a container needs to drain well yet retain sufficient moisture to promote good growth.
Make sure you purchase mixes specifically labeled "potting soil" for use in containers. Mixes labeled "top soil" or "garden soil" are not suitable, because they are too heavy and will not drain rapidly enough. For the same reason, soil dug up from a garden bed outside is not suitable either – no matter how good it seems to be.
Plants growing in containers are far more dependent on you for adequate water than plants growing in the ground.
Water container plants whenever the potting medium begins to feel dry when you stick your finger into it. Or water at whatever interval past experience has shown to be appropriate.
Watering frequency will vary depending on the type of plant, time of year, temperature and size of the plant in relation to the size of the container – among other factors.
At any rate, avoid allowing your plants to wilt before watering, because this is damaging and can lead to bud drop or leaf drop.
When you water, water generously until water runs out of the drainage holes.
The roots of container-grown plants are growing in a confined area, and constant watering leaches nutrients rapidly from the soil. That means more frequent fertilizer applications generally are required when compared to the same plants growing in the ground.
An adequate supply of nutrients is especially important when the plants are in active growth.
The best choices for fertilizing container plants are either soluble fertilizers or slow-release fertilizers, since they are less likely to burn plants when used properly. Never apply a fertilizer at higher rate than what is recommended on the label.
Container plantings enrich our landscapes in wonderful and unique ways. With proper selection and care, they can provide year-round beauty to liven up a variety of landscaping situations.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.