[Image: plants in pots]
For Release On Or After 05/24/13
By Dan Gill
LSU AgCenter Horticulturist
Nearly any plant may be grown outdoors in a container as long as you provide the requirements that the plant needs. Even commonplace plants take on a distinctive quality in containers. You can choose from small-growing evergreen or deciduous trees, shrubs, ground covers, herbaceous perennials and annuals.
Indeed, containers filled with a variety of colorful, compatible plants are all the rage these days. In this planting style, plants are chosen almost as you would select cut flowers for a flower arrangement. The focus is on combining different plant shapes and colorful foliage and flowers in an aesthetically pleasing way.
Besides how they look, other considerations in plant selection include their color, size, shape, texture. The amount of available light where the container is located is the most important factor to take into consideration when selecting plants. 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 can be an important factor. Generally, choose hardy plants that can survive winters outside. That way you won’t have to lug large, heavy plants and containers into protected locations when a freeze threatens.
You can use a large variety of manufactured containers and found objects varying in size, material, color, shape and design for plantings. Only your imagination and taste set the limits.
When you want the plants to be the stars, try to use containers that have muted colors and are simple in design because brightly colored and heavily decorated pots will detract from the plantings. In certain settings, however, you may feel more elaborately decorated and brightly colored containers are appropriate.
Choose larger-size containers whenever possible. Small containers are usually out of scale with outdoor landscapes and require more frequent watering.
Make sure the containers you use have adequate drainage holes in the bottom to allow excess water to drain out of the pot when you water. This is critically important.
More than anything else, the soil or potting mix a container needs to drain well yet retain sufficient moisture to promote good plant growth. Make sure you purchase soil mixes specifically labeled “potting soil” or “potting mix” for use in containers. Mixes labeled “topsoil” or “garden soil” are not suitable because they are too heavy and will not drain rapidly enough. For the same reason, soil dug from an outside garden bed is not suitable either.
Many potting mixes are composed of peat moss, perlite and vermiculite in varying proportions. Their advantages include excellent drainage, light weight and good water retention. However, they can dry out rapidly and may be hard to rewet when very dry. The main drawback is that they are relatively low in nutrients – a problem easily corrected by the use of slow-release or soluble fertilizers.
Plants growing in containers are far more dependent on you for adequate water than plants growing in the ground. When you water, water generously until water runs out the drainage holes. Water again whenever the potting medium begins to feel dry to the touch or 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. Avoid allowing your plants to wilt before watering because this can damage the plant and lead to bud drop or leaf drop.
If the potting mix becomes especially dry, it may be difficult to rewet. Apply water until the potting mix absorbs and retains it. To facilitate watering, the top of the soil should be below the pot rim. This is called head space, which provides an area to hold water while it soaks into the medium.
The roots of container-grown plants are growing in a confined space, and constant watering leaches nutrients rapidly from the soil. Because of this, fertilizer applications are generally required more often than for the same plants growing in the ground. An adequate supply of nutrients is especially important when plants are in active growth.
The best choices for fertilizing container plants are either soluble fertilizers or slow-release fertilizers. Soluble fertilizers are easy to apply, especially when you use a hose-end applicator. But they must be applied every two weeks to maintain a constant supply of nutrients. Slow-release fertilizers provide nutrients over several months from one application, which cuts down on labor.Rick Bogren