Discerning gardeners will always hear alarm bells when plant encyclopedias include words like “vigorous” and “suckering” in their descriptions.   And rightly so; such terms are usually extreme horticultural diplomacy – what they really mean is “beware, this plant has ambitions beyond the scale of your garden, it wants to take over the world”.

Kerria japonica (”Batchelors’ Buttons” is probably the most common of its common names) definitely falls into the “plant with caution” category.   Its a super plant – vigorous slender stems hold attractively toothed and veined deciduous mid-green leaves, and in late spring it’s clothed with loads of bright buttercup yellow flowers.   It’s up there with Forsythia in the spring colour charts.

The weeds have long since given up and moved out...

But you know there’s bad news coming don’t you?   And the bad news is that it’s not a plant that wants to share its space.  Put it in a spot that it likes (and that means almost anywhere) and it will spread, big time.   The picture shows a thicket in our front garden, planted as a single 3lt shrub only 3 years ago.   Its now covering an area maybe 2 mts x 2 mts, and advancing!

It’s very easy gardening, and if you have the right spot, we’d recommend it heartily.   It’s used extensively in amenity plantings (office block shrubberies, supermarket car parks etc) and is particularly good on banks where maintenance is difficult, because essentially, unless you’re worried about containing its spread, it’ll look after itself. It’s vigorous enough to out-compete weeds very promptly.

So if you have a “difficult” spot in your garden, Kerria japonica is likely to fill it nicely for you.   And in fact, although it grows like topsy, it isn’t difficult to control.   We’ll set about ours in late winter by going around the perimeter of the clump with a spade, and digging out the shoots which are exceeding the plants’ allotted space.   The suckers by which it spreads grow just below the soil surface, so it’s not difficult digging. Repeat every 2 or 3 years and this should keep it in check.

If you want to reduce the density of the thicket itself, prune the 2 – 3 year olds stems back to ground level, leaving just the newer (and frankly, more attractive) stems to flower. This greatly improves winter interest as the bare stems are attractive in their own right.

This entry was posted on Wednesday, December 30th, 2009 at 16:39 and is filed under Plants. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.