Plug plants are seedlings which have been germinated and grown in trays of small cells. When the roots have grown sufficiently they can be easily pushed out of the trays and either transplanted into larger pots or planted outside in the ground. Plug plants used to be largely confined to bedding plants and flowers but all that is now changing as edible gardening becomes more popular. Many nurseries and seed companies have started to sell a range of vegetable plug plants and these offer a very easy route to starting a productive garden. So what are the benefits of using plug plants and are they worth producing yourself?
The principle advantage of plug plants is that the roots can be kept relatively undisturbed when transplanting them into their final growing position. Even the most experienced of gardeners will end up losing some soil from around the roots when seedlings are eased out of seed trays. Growing them as plug plants helps minimize this because the shape of each cell encourages the roots to bind the soil into a single plug which doesn’t fall apart when removed. The densely packed trays also mean they are a very economical way to raise plants, particularly if windowsill or greenhouse space is limited.
This year I have decided to experiment with growing my own plug plants, starting them off on an indoor windowsill. Although I could buy them from a garden supplier I chose not to because:
- Growing my own plug plants gives me access to a much wider range of varieties than are commercially available. My first tray, for example, consisted of 14 different varieties of lettuce and salad leaves.
- Home grown plug plants are cheaper and can be raised in several batches to allow for variables which can’t be controlled such as a cold spell of weather.
- Few plug plant suppliers offer organically grown plants. I suspect that the huge greenhouses they are raised in require plenty of pesticide management techniques that I prefer to avoid.
That said, the option to supplement a garden with commercial plug plants is certainly one I can understand. Raising young seedlings inside is time consuming as they need carefully looking after at each stage – moisture levels must be just right, plenty of light but away from draughts and cold etc. Get it wrong and they end up with stunted growth which they may never fully recover from! So, buying young plants from a local nursery or mail-order catalog is an attractive alternative if you want to guarantee success or replace any early-season disasters.
For starting off the seeds I used a great product produced by Agralan from a clever Swedish design called the ‘Compact Plug Plant Trainer’ (available in North America from Veseys). Each tray fits neatly onto a window ledge and consists of 49 cells. The bottom of the tray acts as a water reservoir with an ingenious capillary system to draw up just the right amount of water. The lid can be orientated to allow ventilation or keep in warmth and when turned upside down it creates small dents in the soil for locating seeds. Finally, when the plug plants are ready (shown by a few roots making it down through the bottom of the cells) two side catches are released and the bottom tray pushes the plug plants up and out.
[In many ways this is the baby sibling of the increasingly popular Root-trainers which are similarly shaped pots, encouraging the good deep root growth which is particularly useful for pea and bean crops. The main difference is that Root-trainer pots divide into two halves to access the plant, whereas the Agralan Plug Plant tray pushes them out from below.]
As the plants begun to reach the necessary size I started the usual process of taking them outside for increasing periods of time during the day to harden them off. Then, simply pushing the plants out with the bottom tray I was able to transfer them into my newly prepared salad bed (complete with slug trap of course!) An added advantage that I had not anticipated was that this made it much easier for my 7 year old son to help me. I am normally rather protective about the seedling stage, when so much careful attention has gone into raising these precious little plants. The plug plants were so simple that my son quickly got the hang of making a hole in the bed with a dibber, lifting the plug plant up by the leaf (to avoid squashing the stem), dropping it into the hole and gently firming the soil around it.
Overall, the process has been no more difficult than my usual indoor seed sowing but with some clear advantages. Less disturbance to roots, a self-watering system which worked well and the opportunity for my young children to be more involved with this early stage of gardening. I will be keeping a close eye on the plants to see how they compare to my usual crops but my expectation is that the lack of root disturbance will produce excellent results. Raising your own plug plants may not have the convenience factor of buying them from the nursery but the satisfaction of growing many varieties from seeds makes up for that. I think I am well and truly hooked on plug plants!