seed planting and propagation
seedling propagation
commercial seedling propagation boxes
The standard commercially made seedling propagating boxes that are widely available at Australian nurseries and hardware stores have their uses for the home gardener, but they also have some shortfalls.  This section looks at the advantages and disadvantages of using this type of commercial seedling propagation box.


advantages
Photo of empty commercially made seedling propagation box.
Empty commercially made
seedling propagation box
Can be used with heating trays
Unlike styrofoam seedling propagation boxes they can be artificially heated by placing them on a heat mat, which makes them ideal for growing seedlings that require a lot of heat such as basil, capsicum and eggplant.

very lightweight
As they are small and made entirely out of plastic they are very lightweight, even when full of seedlings.  This means they can be easily moved around.

ready to use immediately
No construction required, just fill with seedling mix and plant.

handles a variety of different pots
The horticultural industry produces a variety of small pots that have been specifically designed for the tray size used as the base for these units.




disadvantages

Prone to over heating
Illustration showing how heat builds up in a commercial seedling propagation box.
On warm days commercial seedling propagation boxes heat up faster than the heat can removed via the vents.

Illustration showing how  a commercial seedling propagation box cools down at night.
On cold nights they quickly lose heat because of the lightweight plastic construction, small size and low mass.
All the commercial seedling propagation boxes available on the market have vents that are too small for proper air circulation.  This means that on even a mildly warm day the heat can build up inside the box to such an extent that the seedlings literally cook.  If you use one of these units then I suggest you remove the vent covers (flaps or tags that can partially or fully close the vents) to maximise air flow.  And if it looks like being a warm day then completely remove the plastic dome.


lose of heat at night
Due to their lightweight plastic construction commercial seedling propagation boxes have poor insulating qualities   Their small size and the small amount of seedling mix that they can hold also means that they have no mass to store heat.  So on a cold night they quickly lose heat. 

Seedlings that require high soil temperatures even at night, such as basil, capsicum, cucumber and eggplant, are more prone to rot when grown in these boxes.

Expensive
Commercial seedling propagation boxes retail for around $25 to $30 AUD, where as the cost to set up a styrofoam seedling propagation box  is lest than half that price.


Limited lifespan
Although their clear plastic domes are made of UV resistant material they are so thin that they usually begin to break down within about three years.  These domes usually do not last more than five or six years, though their life can be prolonged by storing them away from direct sunlight when not in use.