The standard commercially made seedling propagating boxes that are widely available at Australian nurseries and hardware stores (such as the Yates Mini Greenhouse) 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.
- 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.
- SINGLE CELL SEEDLING TRAYS CAN BE USED IN THEM
Commercial seedling propagation boxes can handle single cell seedling trays. These trays are useful for growing seedlings (such as pumpkin, zucchini and corn) that do not like their roots being disturbed.
Single cell seedling trays that can be used in commercial seedling propagation boxes.
- PRONE TO OVER HEATING
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 keep the vent holes permanently open or even remove the air vent covers (flaps or tags that are used to partially or fully close the air vents) altogether. The best way to regulate the temperature is to remove the lid itself on warmer days, replacing it when the temperature cools down at night.
- COOL DOWN QUICKLY 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. Which means that on a cold night they cool down quickly. Seedlings that require high soil temperatures even at night, such as basil, capsicum, cucumber, and eggplant, are harder to grow when grown in these boxes without artificial heating.
- RELATIVELY EXPENSIVE
A typical Commercial seedling propagation box, such as the Yates mini greenhouse, retails for around $30 AUD (2020), whereas the cost to set up a Styrofoam seedling propagation box is less than half the price.
POOR MOISTURE RETENTION
Due to the small volume of propagation mix used to fill them commercial propagating trays dry out more quickly than Styrofoam seedling propagation boxes. Which means you must water the more frequently.
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.
On warmer days commercial seedling propagation boxes heat up faster than the heat can be removed via the vents
On cold nights they quickly lose heat because of the lightweight plastic construction, small size, and low mass.
Air vents such as this should be kept open all the times.
Lids of a Yates mini greenhouse seedling box. the one the left is brand new while the one on the right is around five years old.
There are several different size commercial seedling propagation boxes on the market, this is a Saxon brand mini greenhouse with its vent covers removed.
Commercial seedling propagation boxes are excellent for growing seedlings in single cell seedling trays or seedlings that do better when artificially heated, however these boxes work better when used in a large greenhouse rather as it is easier to control temperature fluctuations in a greenhouse.