Plan on several years, not months. Take a standard, the kind with a bare stem and a clipped head sitting on top. The Royal Horticultural Society puts the job of clearing that stem to full height at several years. Regrowth into shape after a hard prune is a separate few years again. Topiary growing time for a plain ball or cube has no published figure at all, so anyone who quotes you one is guessing.
The boxwood balls along my front walk hold a clean edge every June, and they have been clipped once each summer since the day they went in the ground. That is the whole bill for a piece that is already made. An established specimen wants trimming once or twice a year, in early or late summer. A vigorous species asks for more, sometimes twice or more each season.
Two limits set the topiary time to shape, and neither one bends for you. Never take off more than one third of a plant's total crown in any one year, and that ceiling bites hardest on mature or older plants. The second limit is where the new growth lands. The most vigorous regrowth always comes within 6 to 8 inches (15 to 20 cm) of the pruning cut, so the surface fills in cut by cut instead of all at once.
Species does the rest of the work on the clock. How fast topiary grows tracks the vigor of the plant you started with, and the split shows up in how much trimming a plant demands. One that is happy with one trim a year takes longer to fill a frame than one asking for two or three cuts a season. Faster growth buys you a finished shape sooner. Then it charges you every summer after that.
Trim an established topiary in early or late summer. On a vigorous plant, expect twice or more in a season, and never take more than one third of the crown in a single year.
A ball on a short trunk is one job. A spiral or a bird is another, and no source puts a number on either. What you can count on is the pattern of the work rather than a date on a calendar. Each trim tightens the outline, the plant answers close to the cuts, and the outline reads solid from the path after a run of seasons. The slow part is density, and size arrives well before it.
First seasons
Let the plant put on growth. Feed it with a spring mulch of organic matter and shape lightly.
Several years
Clear the lower stem of a standard a bit at a time until the head sits at the height you want.
A few years after a hard prune
Regrowth fills back into the shape you cut for. There is no shortcut through this stage.
Every year after
Trim once or twice, in early or late summer, and more often on a vigorous plant.
Every three to five years
Hand-thin the surface so the plant keeps depth instead of leaves over bare wood.
The maintenance clock surprises people more than the build does. Shear a plant year after year and the leaves thin into a shell over bare wood, so hand-thin the surface every three to five years to open it back up. An annual spring mulch of organic matter keeps growth strong enough to take the shearing you give it.
Buying a trained specimen skips the wait, and for a standard I would pay for that. All the topiary growing time already happened in someone else's nursery, and the price tag says so. Grow your own if the shape is simple and you like the clipping. Buy it if you want the head at eye level this season.
Read the full article: Topiary: How to Shape Plants Without Killing Them
