Sometimes referred to as open ground, the term refers to the fact that the plant is usually still dormant and will be sent without soil or a pot.
There are many advantages to buying and selling plants this way. The most obvious is the reduction in packaging, especially parts of packaging that most councils cannot currently recycle. Sending plants without soil also reduces the weight of the parcel, thus reducing the CO2 produced by our courier while your parcel is in transit. There is also a reduced risk of weed seed and pest transference.
The only slight draw back is that it may take your plant a little bit longer to get going but by following the aftercare advice supplied with your purchase your plants will soon catch up.