Those of you who have been with us for a while know I love to slip-pot trees. Why? Well, I guess the biggest reason is I’m impatient to see a tree progress toward its best self. Another reason is that a lot of trees pass through my hands, and often it’s just time to go ahead and get a tree into a bonsai pot and move on to others. Slip-potting usually saves at least half a season in terms of getting a tree to a good showable state. So there you go.
With that said, however, there are some rules that have to be followed if you want to see your trees progress faster to your ultimate goal (meaning the slip-potting has a positive rather than negative outcome). Here are some I adhere to, in no particular order:
1. The tree must be healthy with good vigor. I know, this goes without saying but it never hurts to bear it in mind.
2. The tree either has to have a complete trunk line, or be vigorous enough so that you can complete your trunk line in a bonsai pot. Shallow pots slow growth, always.
3. You need good roots. Foliar vigor isn’t always reflected below the soil, and this is especially true for species that don’t grow roots quickly (such as hollies).
4. The pot your pre-bonsai is growing in should be very similar in size and configuration to the bonsai pot you intend it to go in. Which is another way of saying you want to avoid removing any roots, to the greatest extent you can.
5. Only slip-pot when there’s time in the growing season for the tree to recover from the move. Or, put another way, don’t slip-pot in winter. That leaves three whole other seasons, so you should be able to get your fill of slip-potting while it’s warm.