Plants That Bear Watching

Every garden probably has a few. Not exactly weeds, but tending toward the weedy, yet something about them holds you in thrall. Keeping these plants in the garden is flirting with disaster, but still you just can’t break it off. Maybe these exuberant, sassy, lust-for-life types are a bracing contrast to those plants perpetually teetering on the verge of fainting dead away. They’re dangerous, yes, but also a quick source of cheap thrills. In my garden, the following four easily fall into the PTBW category, all deserving extra vigilance for their great foliage, which is evergreen here in zone 10:

So far, tetrapanax seems reasonably well behaved. Far better manners than, say, acanthus. Maybe my heavy clay soil keeps the infamous running roots in check, but it’s only been a year, so too soon to tell. (Edited April 2011: Runners found 2 feet away.)


Bronze fennel, Foeniculum vulgare, on the California invasive plant list. Robust and feathery, I’ve kept just one plant, don’t let it set seeds, and haven’t had any seedlings yet. So far so good, but not to be grown near wild, open areas.


Castor Oil Plant, Castorbean, Ricinus communis, ‘New Zealand Purple,’ holding on to a few leaves through the winter. It just occurred to me that the castor oil tablets my mom gave us as kids come from this deadly plant. Weird. An escaped weed in Southern California and also meriting a spot with fennel on the California invasive plant list. No seedlings from this cultivar so far. (Edited April 2011: One seedling found and carefully transplanted. Just one.)


Corydalis heterocarpa. Probably no more prolific than C. lutea, with similar yellow flowers, but since it grows as big as rhubarb the scope for trouble is that much greater. Truthfully, this plant has passed over into the weed category, and I no more “keep” it than one “keeps” ants in the garden, but easy enough to hoe out the seedlings. Each year the fresh leaves in spring win me over again.


I appreciate these hooligans for keeping the garden lively, but like all hooligans, they straddle a very fine line between lively and obnoxious.

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3 Responses to Plants That Bear Watching

  1. Scott Weber says:

    Of the 4, I’ve only grown the fennel and the castor bean. I’ve never had trouble with the fennel becoming a pest…it reseeds, but not to any great degree…and it’s easy enough to weed them out if they pop up in a bad place. I’ve never had a tetrapanax, but I’ve seen some pretty scary pics of the roots on them…I think it takes a few years, but eventually they can form a “trunk” underground! Good luck!

  2. Grace says:

    My tetrapanax is only a few years old too and so far just a single trunk. I finally got rid of all my bronze fennel. Although I love the foliage, the mustard yellow flowers weren’t to my liking so I was constantly cutting the plant down only to have it rise up again and try to bloom. Plant torture, anyone? Feverfew is a bane in my garden. I love the small white daisylike flowers but it reseeds everywhere. Centaurea montana is also a bane and no longer in my garden. And we won’t go into all the reasons why I never should have planted Bishop’s weed. … Great post, Denise.

  3. Denise says:

    Scott, I hear tetrapanax can bust through concrete. I’m hoping only in the PNW!
    Grace, I love Centaurea montana! Won’t grow for me at all. Believe it or not, my next-door neighbor grew bishop’s weed. I thought it was gorgeous. No problem with spreading since it’s just too dry here.

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