Moving house plants starts a week in advance
Plants are the most delicate load you'll carry in a van. They have no packaging, can't cope with being tipped over and react badly to frost and to several hours in the dark. So plan moving your house plants separately, not as an afterthought to the furniture.
Water well in advance
Give them their last proper watering three to four days before the move. On moving day the compost should be slightly moist. Wet soil is heavy, crumbles and the water leaks onto whatever is under the pot. A completely dried-out root ball, on the other hand, weakens the plant exactly when it has to cope with stress.
Check plants for pests
There's no point taking spider mites to your new flat. Check the undersides of leaves, the rims of pots and the surface of the compost. Treat affected plants at least two weeks in advance. In the van the plants will be squeezed together and an infestation will spread to the rest of your collection.
Put off repotting
Don't repot just before moving. The plant would be dealing with two stresses at once, and a freshly repotted root ball falls apart when tilted. Save the new pot for when the plant has got used to its new spot — a month after the move is fine.
What to wrap plants in
A box without a lid is better than standing them loose
The safest packaging is an ordinary sturdy box. Several smaller pots will fit into one and support each other. Fill the gaps with scrunched-up paper or tea towels so the pots can't shift. Line the bottom of the box with plastic or an old towel.
Protect the leaves, not just the pot
It's usually the leaves that break, not the pots. Loosely tie up bushy plants with string or wrap them in a paper cone so the branches don't stick out. Only use plastic for a few dozen minutes, otherwise the plant will sweat underneath it.
Stand large plants on a tarp
You won't get ficuses and palms into a box. Stand the pot in the middle of an old tarp, pull the corners up and tie them around the trunk. That gives you something to hold the plant by, and the soil won't end up all over the van.
Transport ceramics separately
Heavy ceramic pots are the most common cause of damage. They break, and so does whatever they fall on. With large plants, take out the plastic inner pot with the root ball and transport the outer pot separately, wrapped in a blanket. You put them back together in the new flat.
Label what's inside
Mark boxes of plants on all sides. Whoever carries one must know it mustn't be turned over or put in the middle with things stacked on top. Big lettering and an arrow pointing up are enough.