Branches are made while the lace is still pinned to the pillow, and all threads wound on the support bobbins. The work itself is can be viewed as combination of bobbin lace and hair braiding. As long as you know at least one of those techniques, you will do just fine.
First, unpin all footside support pins and two concentric rows of torchon ground (the section of lace that was not starched.)
Lay a cover cloth over the bottom part of lace, covering the holders with bobbins.
Start working from the crown top centre: use three bobbins and make a short braid.
The bobbins for braids do not have to be consecutive. If one bobbin is skipped (to be included in the next braid), it will create an illusion of crossing branches.
Braid more branches. They look somewhat loose and limp at the beginning, but that’s OK, their shape will be adjusted later, as the braiding progresses.
Combine two neighbouring branches into one braid…
… and next two branches into another arm. A French braid technique might be helpful here, but anything that will combine two braids in one will work. You can always go back and re-braid, if you don’t like the joint.
Slightly below the centre of the pricking, bring the top branches together to start forming a trunk.
With many bobbins together, the braids become quite heavy. They can be propped by strategically placed divider pins. This relaxes the branches and gives them slightly curvy, natural shape.
Braid the pairs from the last row into a tight plait towards the tree trunk.
Repeat on the other side, and bring in the threads from the starting row.
All threads are now incorporated in the trunk. Divide them into three groups.
Plait the main trunk. Tension the braid quite tightly so it holds together for now. It can be relaxed and shaped later, before the start of the root work.
Unwind and remove the bobbins.
Cut the threads. It is preferable not to cut the loop in the very centre, but a little to the side…
… this way, the ends will be of unequal length, which will be useful in the root work.
Unpin all pins. For easier move from the pillow to the background, fold the loose threads in a cover cloth.
The tree is ready to be transplanted.