Five years ago several seed companies began selling plug plants of annual flowers and vegetables directly to gardeners through the mail. Plugs--small but well-established seedlings grown in wedges or "plugs" of soil mix--are one of the latest products of high-tech horticulture. For wholesalers, the narrow, tapered rootball is often quite small. The ones in seed catalogs are a little larger than the average garden center six-pack cell. The plants are very compact and actively growing, so they will ship economically and safely over long distances. They then grow quickly once they are transplanted.
Commercial bedding-plant producers used to buy seed in large lots. Today more and more of them are buying plugs instead. These growers raise the plugs up to the blooming stage, then sell them to nearby nurseries and garden centers. If you buy plants at a large garden center in spring, chances are very good that some of them were raised from plugs.
Growers like plugs because they can forget about dealing with finicky and often tiny and expensive seed. They can forget about light and temperature controls and about damping off and other diseases.
Are plugs better for gardeners, too; if you want to try them in your garden, now is the time to place orders.
Gardeners should like plugs for some of the same reasons nurseries do. Good plugs are stocky and actively growing, both above ground and below. By contrast, blooming garden-center plants have reached an end point. Once plants begin flowering, new leaf and root growth is put on hold. Moreover, garden-center plants have often completely filled their soil mass with roots and need watering daily. After a week or so in this state, it's very likely that they will undergo severe stress at least once, which makes them slow to grow once they're set into the ground.
The varieties available as mail-order plugs may be better selections for the home garden, too. At garden centers, most varieties have been bred for "pack performance," which means they can be brought into flower very quickly. Nursery shoppers prefer to buy color rather than greenery, even though plants not yet in bloom will probably grow better in the garden. Companies selling plugs stress that they offer top garden varieties, things that you are unlikely to find at garden centers.
We were interested in seeing how much better the younger root systems and plants would perform in real gardens. We were also concerned about how well these little plants would come through the mail. Would they still be spunky and ready for a sprint after a long, dark truck ride in who-knows-what heat and cold?
But, you need to go early and often to be sure of getting the things you want before they become root bound or otherwise stressed.
Jack Ruttle is a former editor at National Gardening.
Photography by John Goodman
Article published on June 23, 2008.