No, brunnera fast growing is not a fair claim for this plant. Brunnera grows at a moderate pace that suits most shade gardens just fine. You can expect a small starter plant to reach full size in about three years with good care. The slow growth means the plant stays put without taking over your beds.
Brunnera growth rate works on a slow but sure path each year. The plant puts on two to four inches (5 to 10 centimeters) of new growth each season. This may sound slow but adds up to a big plant in just a few years. The roots push out new shoots at the edge of the clump as the seasons pass.
When I first planted a one gallon Jack Frost brunnera, the clump was just 6 inches across. I watched it grow over the next three years with steady but slow gains. By year two, the plant hit about 12 inches wide. By year three, it had reached the full 18 inch mature size with lots of pretty silver leaves.
The growth happens through short rhizomes that push out from the main crown. These thick root stems extend the clump by a few inches each year. New leaves push up from the rhizomes in spring and fill out the clump. The plant gets denser and fuller each year as the rhizomes multiply under the soil.
Brunnera mature size is about 18 inches tall and wide in most cases. Some big-leaf forms can reach 30 inches across at full size. You will hit these sizes in about three to four years from a one gallon starter pot. Smaller four inch pots may take a full year longer to catch up to gallon plants.
I have found a few clear milestones to watch for as your brunnera grows. Year one is all about root growth, with little visible change above the soil. Year two brings a full leaf canopy and the first big spring bloom show. Year three gives you a mature plant with full size and full flower display.
By year four, the clump is ready to divide if you want more plants for free. Divisions can fill in other shady spots in your yard or go to friends. The plant will not need division for health reasons until year five or six in most cases. Brunnera spreading time stays slow enough that you have full control over the size.
You can speed up brunnera growth with a few simple tricks at planting time. Mix two inches (5 centimeters) of compost into the planting hole before you set the plant in. This rich soil helps the roots grow fast in the first year. I always add a handful of slow release fertilizer at planting too for an extra boost.
Mulch each spring with a two inch (5 centimeter) layer of shredded bark or leaf mold. The mulch keeps soil moist and cool, which brunnera roots love best. Water your new plants well during the first summer to help them settle in. Once established, brunnera needs less water and care to keep up its growth pace.
When I first started growing brunnera, I worried about the slow pace early on. Now I know the slow growth is part of why the plant is so easy to keep happy. You get a plant that fills in just right without ever getting out of hand. Brunnera rewards your patience with years of beauty in your shade beds.
Read the full article: Brunnera Plant Growing and Care Guide
