Plant a young nandina and you will see steady new cane growth push up from the base each season. It does not thicken slowly into one trunk the way a tree does. That base growth is the real story behind the nandina growth rate, which extension sources rate as rapid. A healthy young plant fills out and reaches its mature height in just a few years under good conditions.
So how fast nandina grows comes down to how it builds itself. Each spring the plant sends fresh canes straight up from the crown at soil level. Those new shoots reach close to full height in one season. The clump gets wider and fuller as more canes join the cluster year after year. You are watching a colony fill in, not a single stem creep upward.
This is why the word maturity means something different for nandina. A tree takes years to size up its trunk and crown. Nandina hits its full height fast and then keeps thickening as a clump. The plant looks established once it has a dense stand of canes, not after some long wait for one stem to grow tall.
Here is what that looks like in real numbers. The typical nandina mature size in a landscape is 3 to 8 ft (0.9 to 2.4 m) tall and 2 to 5 ft (0.6 to 1.5 m) wide. Most garden plants settle in the lower half of that range. You may read that nandina reaches 10 ft (3 m), but that height shows up mainly on wild plants, not the shrubs in a normal yard.
Growth rate is rapid. A young plant reaches mature height in a few years. Landscape size runs 3 to 8 ft (0.9 to 2.4 m) tall and 2 to 5 ft (0.6 to 1.5 m) wide.
Good conditions speed all of this up. Give your nandina decent soil, some sun, and water through its first year or two. The canes come up faster and the clump fills out sooner. Skimp on those and the plant still grows, just at a slower pace with fewer new shoots each season.
Use that fast fill-in when you plan your spacing. A small plant from the nursery looks tiny in the ground, so the urge is to set plants close for an instant hedge. Resist it. Those gaps close fast once the canes start climbing. Crowd the plants now and you get a tangled mess that needs thinning in two or three years.
Space each plant for the width you actually want at maturity. For a low border, set the smaller clumping types about 18 to 24 inches apart. For a taller screen, give the standard shrubs 3 to 4 ft of room so each clump has space to widen. The plants knit together on their own as the new canes spread out from each base.
Patience helps in that first year. A young plant often spends its early months building roots before it pushes much top growth. The canes may seem slow at first. Then the plant takes off once the roots are set. So do not judge the nandina growth rate by what you see in the first few weeks after planting.
You can shape the clump as it fills in. To keep a plant dense and low, cut the tallest canes right at the base in late winter. This pushes fresh shoots from the crown and keeps the stand bushy. Skip the haircut and the plant grows taller and leggier over time, with bare canes near the ground.
Bottom line: nandina grows fast and reaches its full height in just a few years. But it gets there by stacking up new canes from the base. One stem does not race skyward. Plan for the 3 to 8 ft (0.9 to 2.4 m) size it will hit. Space with that fast fill-in in mind, and you will not fight an overgrown clump later.
Read the full article: Nandina Domestica Care and Cultivar Guide
