Weed of the Week - crabgrass

In the spirit of if-life-gives-you-lemons, make-lemonade, TPP decided to do a weed of the week, although this feature will probably be a bit more irregular.  Partly this is because, like other plants, weeds are different in different parts of the world, and TPP forgot that everyone might not know what crabgrass is until after being reminded of this by a reader.

Crabgrass is one of several species of Digitaria (not Digitalis, foxglove), our predominant species is D. sanguinalis, hairy crabgrass, is a C4 annual, which explains why it grows so well in our dry, hot summer season.  You may have to look up C4 photosynthesis if you don’t know what this means. The details are not important, but it means C4 plants are more efficient, or less wasteful, at higher temperatures or under drought conditions.  Crabgrass can easily overgrow other plants and because it roots down along the way it can be tough to pull, and even leave a blank space if pulled and opening other weeds can exploit.  

This is a tough weed to control and the bane of lawn purists.  In the late spring people can treat their lawns with a pre-emergent herbicide and prevents the crabgrass from germinating.  In isolated patches and small areas the seedlings, easily identified by their broader and more upright blades, can be plucked from you lawn or hoed out of a garden bed.  At a more mature stage pulling or hoeing is not practical. 

If it takes over more than 60% of your lawn, most experts recommend nuking the area and starting over.  Really dense turf grass can resist crabgrass, but that takes watering and fertilization. And TPP didn’t want turf grass in the first place, so that’s rather counterproductive unless you are a lawn purist.  In TPP's grassless-shady-lawn world where it's one weed vs. another, blue violet and creeping Charlie, Glechoma hederacea, both do better than crab grass, so the better weed wins, so to speak. Still TPP had no trouble finding some to photograph in a sunnier garden bed.

The Digitaria (fingers) part refers to the long narrow inflorescence of tiny “seeds”, in parts of Africa a species is grown for its cereal grains called fonio. 

Here overgrowing a pink's foliage.

Friday Fabulous Flower - Flower of an hour

Well, Friday got away without a flower.  Here's one that TPP likes even if it is a weed because it does have a pretty flower, and large for the size of the plant too.  This isn't a common weed in our urban gardens, and it actually isn't difficult to control, but the city took out a soon to be dead white ash and brought in some city soil with what are more common agricultural weeds in the area, and it contained seeds of two members of the same family.  Here abouts this is called "flower of an hour" (Hibiscus trionum) because the flower doesn't last long.  The five red stigma lobes mark this as a hibiscus.  The rest of the flower is a classic mallow (family) famous for the spongy white roots of the marsh mallow.  The other weed is velvet leaf - Abutilon theophrastii that was probably imported to N. America for use as a fiber plant, a failure obviously.  Flower of an hour was also imported, perhaps with other agricultural seeds, perhaps as an ornamental.  The inflated and persistent calyx can be seen just above flower, and out of focus.  The bull's eye floral image is even stronger under UV light. 

Plant this weed - Sure!

There are plants that just should not be planted.  The Phactor has already warned you about plume poppy and presently is struggling to eradicate Houttoynia crodata, the newest addition to my do-not-plant-this-plant list,  from an planting enclosure (even that did not work to contain it).  So here's one of the darlings of the Chelsea Flower Show, and just looking at this and my gardeners instinct rebells at the idea of planting this plant.  See!  It's clearly a weed; too closely related to a troublesome weed to be worth the risk even it this species (Chenopodium giganteum) is prettier than its well known weedy relative.  Read the endorsement!  It's edible.  Big deal.  Most chenopods, indeed, most weeds are edible when young (and there's a biological reason why).  It's free seeding!!!  Yikes, that should be warning enough.  Translation: This is a bloody weed whose seedlings will drive you crazy.  Oh, just thought of another entry for the do-not-plant-this-plant list, but it will wait for another blog.  So who does Chelsea think she's kidding.  It'll take more than an appearance at a famous flower show to convince this gardener that planting this plant is worth while.