Tropical-looking Gunnera will give your garden a Jurassic Park feel

In the Garden

Q: When can I transplant my Gunnera?

A: Native to Chile and Argentina, Gunnera tinctoria seems to emerge straight out of Jurassic Park. This tropical-looking perennial sports huge, sharply toothed leaves that can reach more than 8 feet across. Even the enormous corncob flower spike looks prehistoric.

These gigantic specimens are borderline hardy in the Pacific Northwest, so wait to transplant until milder weather occurs in early March, but before new growth begins, usually in April.

Begin digging about a foot out from the crown and you’ll quickly discover the whereabouts of the large rootball. You might want to get a friend to help you lift your Gunnera out of the ground. The roots on a well-established specimen can be incredibly heavy.

When replanting, the trick to growing this goliath successfully is to plant it in moist soil. It can survive in dryer conditions, but you’ll have to mulch heavily and provide almost daily watering to ensure that the soil remains moist at all times.

To achieve honker status, feed at least 3 times per year with organic, high-nitrogen lawn fertilizer. Every year, when the leaves begin to die back in October, cut the stems where they attach to the crown; then turn the huge leaves over and use them to cover the crown to protect it from cold damage. Remove the upturned leaves when new growth emerges again in early spring.

Q: Last fall I planted some hardy mums that were slightly taller than 1 foot. When they came back this year, they grew to nearly 5 feet. What variety grows tall like that?

A: Depending on the variety, many hardy mums naturally grow tall. Although there are dwarf varieties available, the ones you planted remained compact during the first season only because they were sprayed with growth regulators at the nursery where they were grown. By the following spring, the effects of the sprays have worn off, and they quickly revert to their natural taller-growth pattern.

Furthermore, garden mums require full sun; otherwise they will become leggy and thin, set few buds and sometimes flop over. Even the dwarf varieties tend to grow taller and thinner the second year.

Fortunately, there are steps you can take to keep your mums, even taller-growing varieties, compact and floriferous. In early March, transplant any mums that are in shaded conditions to an open, sunny location. Make sure your mums receive regular watering, and fertilize every six weeks with an organic flower food.

As soon as spring growth reaches 6 inches tall, shear the stems back by a third. Repeat the process every three weeks until about late-July, or as soon as you notice buds starting to form. Once the budding process begins, don’t shear again, or there’s a good chance your mums won’t bloom in the fall.

Over time, you’ll probably notice that some of the older mums in your garden begin to bloom less as they age. That’s a sure sign they’re becoming woody in the center and need dividing. In early March, dig up the plant and use your digging spade to slice off the outer third of each side of the rootball. Replant those and compost the middle section. Treat your new plants as described above and you’ll be rewarded with gorgeous late-season flower displays on compact plants every year.