Dig up bishop’s weed

I recently read the article you did on bishop’s weed. I have a shaded yard and have lots of both shade and bishop’s weed. I really like how bishop’s weed brightens the shaded areas, however, I have a major problem with it: It has reverted to its all dark-green state for some reason and has really taken over my yard as it is very aggressive. The dark green type seems much more so than the variegated kind. Do you know why it reverted and how I can kill it off and stop it from spreading to the areas that are not affected by it … yet?

I have tried cutting it down and spraying Roundup on it, but it just keeps on coming up.

Any advice would be helpful. Thanks.

Karen Malone

Hmm, you have at least two challenges here: The first is that your variegated form is reverting. This is not uncommon in the plant world, but it is surprising in that variegated bishop’s weed has been around for a long time so it should change easily. One theory is that a section of the plant reverts and is a stronger grower than the variegated part and takes over. There is nothing much you can do about it, except digging up the green ones and replanting the variegated kind.

To get rid of the green plants try Weed-B-Gon (2,4-D) but expect to make several applications because of the plant’s extensive root system. Wait until the weather cools though to do any spraying as hot weather can volatilize the chemical onto plants you don’t want to hurt. Also, the plants are not actively growing when it’s really hot.

Once you’ve successfully sprayed, then lay weed fabric over the beds and mulch with three to five inches of bark. Once you get the green form out replant with new starts from the nursery. Good luck.

Fight back against blooming algae

I really enjoy your column but recently in a story about water features, you mentioned that maintenance consists of checking water levels and treating for algae. Well, we have a fountain, and it is amazing how fast algae comes back after cleaning and how often we have to clean it out – there’s some work involved there. My question is: Do you know of a product that would slow down algae growth or something else we can do to lessen this problem? The water is self-circulating, and a pipe adds a little water each day from our automatic sprinkling system.

Laurelle Gerber

Algae is a ubiquitous plant that will develop anywhere it can find warm water and bright sunlight – both of which we’ve had a lot recently. If you can keep your fountain in the shade that will deprive the algae of some light and slow it down a bit.

Otherwise, drain the fountain once a month in the hottest weather. Before draining it, brush all the surfaces you can reach with a stiff brush. Once it’s drained, scrub it again with bleach, Listerine, lemon juice or vinegar to change the chemical environment for the algae.

You also can add a commercial algaecide like Fountec to the water to help keep the algae down. You will not get rid of algae but this should at least slow it down enough that you can enjoy your water feature.