Root development and establishment of woody ornamentals grown in containers

This study consisted of a series of experiments designed to establish the responses of plants grown in three container media to three container designs and various backfill compositions. One experiment was conducted to establish the effect of the media particle size on root development and distribution. There was a greater number of Ilex crenata 'Green Luster' roots in the inside and middle concentric areas of the bottom two-thirds of the peat-perlite medium than the other two media in a container of conventional design. There was a greater number of Ilex roots in the outside area of the pine bark-sand media than in the outside area of the other two media. Also in this container of conventional design the number of Juniperus horizontalis 'Plumosa' roots in the bottom depth zone of the pine bark-sand medium was greater than in this zone of the other two media. Vertical dividers in the bottom of the container increased the number of Ilex roots in the outside area of the peat-perlite medium. In the container with vertical dividers the Ilex roots were more evenly distributed through the areas of the depth zones of the soil-peat-sand medium.

Ilex crenata 'Green Luster' plants were grown in four media consisting of different particle sizes of sand. It was found that there was less of the total root system in the low two-thirds of the container media of the smaller sand particles than in the container media with large sand particles.

When Ilex crenata 'Green Luster' had been grown in the peatperlite medium, the addition of peat-perlite to the backfill soil increased the initial root growth through the backfill. After Ilex crenata 'Rotundifolia' and Juniperus horizontalis 'Blue Rug' had been transplanted into the landscape for 15 months there was no effect of container media, backfill composition, or container size on the dryweight of roots that had grown from the original container media.

The daily maximum temperatures were equal at the three locations in the three media at a high moisture content. When the media were dry, the maximum temperature at the top location was greater then at the other locations. The rate of temperature change from the daily minimum to the maximum was greater in the dry media than in the wet media at all locations.