Monday, August 26, 2013

Groundcover Warning: Blue Star Creeper, Pratia pedunculata, Laurentia fluviatils, Isotoma fluviatilis

Blue Star Creeper, pretty flowers, pretty aggressive, pretty finicky about growing conditions, etc.

Blue Star Creeper, a.k.a. Pratia pedunculata, Laurentia fluviatilis or Isotoma fluviatilis


- Spreads fairly quickly. Tiny plants 2-3 square inches can form an expanding patch 10-15 feet wide within 2-3 years.

- Profusion of charming light blue flowers in spring for several weeks. Bloomed starting mid-May this year and was still covered in flowers in early June. In cool summer climates, Blue Star Creeper might bloom all summer. I say that because our temperatures have been cooler than average most of this summer (highs in the mid-80s or lower many days) and Blue Star Creeper started reblooming in late July. The flowers do seem to attract some small bees, wasps and/or hoverflies.

- In spring, the foliage can make a lush green carpet.

- Tough. Survives heat, cold, drought and wet conditions (though it may not look good in the process).


I ripped up a patch of Blue Star Creeper here a couple of weeks ago. Clearly I did not get it all, because bits and pieces are creeping back. Gonna have to try to dig it out again. Could take a few tries (at least) to eradicate Blue Star Creeper from a garden bed.

- Hard to control. Blue Star Creeper spreads on below-ground rhizomes. And it tends to travel a little...unpredictably, not necessarily advancing in a straight line, but suddenly popping up several feet away. When I decided that Blue Star Creeper was insinuating itself where I did not want it, I started digging with my Cobra weeder and found that Blue Star Creeper had made a thick web of white roots below the surface (see photo below). When you try to uproot this Creeper, the roots are likely to break, leaving bits and pieces below ground to resprout. This extensive underground root system makes controlling or eradicating Blue Star Creeper a challenging proposition - at least through manual means. (I have not tried spraying it with any herbicide because I tend to avoid using such chemicals when possible.) Since the plant grows so close to the ground and the leaves are so small, that also makes it hard to get a grip to pull up a patch. The fact that Blue Star Creeper is an invasive exotic is another strike against it since we can't count on co-evolved predators or pathogens to keep it under control. That being said, at least Blue Star Creeper is diminutive. Generally it only grows a few inches tall, so at least it's not about to climb and strangle a tree as kudzu might.

These roots are just a small representative sample of the web that Blue Star Creeper has woven underneath the soil. It's pretty scary stuff. My advice -- stay far, far away. I imagine I'll be fighting to get rid of this for years to come. I wouldn't mind having a small patch, but I don't think that's possible unless I wanted to grow Blue Star Creeper in a pot.

Not native to the U.S. The nomenclature is very confusing on Blue Star Creeper, but according to Paghat, there are actually two different species that are frequently marketed under the same common name, one from Australia and one from New Zealand.

- Doesn't block weeds all that well. Blue Star Creeper's small size may be an asset in terms of making it not-that-thuggish, but it also makes it only partially effective as a weed-blocker. So it's kind of a lose-lose situation - the Blue Star Creeper insinuates itself like a weed, but it's not actually thick or tall enough to shade out other weeds like clover. And as Paghat says, "some weeds are practically nursed by the mat of [Blue Star Creeper] foliage, and weeding will mean ripping out big patches of the ...creeper."

- It just doesn't look that good much of the year. Heat and cold and drought and wetness may not kill it, but they can make it look like Hell warmed over. More specifically, in cold weather, the plant may brown and sort of disappear under the soil. In hot weather (especially in full Tennessee sun) the plant may bake to a crisp and disappear. In drought, you guessed it, Blue Star Creeper pulls a disappearing act. That's sort of a pity, because if the plant were green and mat-forming all year, at least I could consider using it as a lawn alternative (assuming that deep metal or plastic edging could control its spread...which I don't know for sure). It's so low-growing that at least it never needs mowing!


To sum up, Blue Star Creeper is aggressive, invasive (in the U.S.), offers poor weed suppression and has low aesthetic appeal for much of the year. I can't recommend Blue Star Creeper for the Southeast and I certainly would urge caution before adding it to your garden. Read some of the other negative experiences that Dave's Garden reviewers have had. Blue Star Creeper is one of the few plants that I regret planting. I'm now trying to undo that mistake and warn others from making the same error.

PS - If you'd like to stay abreast of the latest developments at Garden of Aaron, you can now subscribe via email! Totally convenient, totally free - what could be nicer?

Monday, August 19, 2013

Too Close for Comfort

Please step away from the wall...  Surely whoever planted this Crape Myrtle realized that it might grow more than 3-inches wide? Generally speaking, if a plant is supposed to grow say 20-feet wide, experts recommend planting it at least ~12 feet from a building, so that it can grow to its maximum width and still give you a little space to get between the building and the plant for pruning, painting, window washing, etc.

When we moved into this house a bit over 2 years ago, we noticed that a number of the foundation plants were sited too close to walls and steps.

Some of those (the Nellie Stevens hollies) we removed.

Some of them (the camellias flanking the front steps, another camellia planted alongside the front wall) have stayed. I can't bear to part with them and I'm concerned any attempt to moved them by 1-2 feet would be detrimental to their health.

But there's one plant that's planted WAY too close for comfort to a side wall - the lavender crape myrtle pictured in the photo above.

I can't be sure (since there are so many crape myrtle cultivars), but I think this could be Muskogee, one of the superior USDA introductions that is resistant to powdery mildew.

Personally, I've decided that I like the white-flowered crape myrtles (such as Natchez) best. Most of the others seem a bit too garish for my tastes. Plus the white-flowered ones seem to attract the most bees! But I do think that the light-lavender flowers of Muskogee (if that's what it is) are probably my favorite among the colored varieties.

So it's painful to think of getting rid of the tree, but we're talking about a plant that will wants to grow 25-feet tall and 20-feet wide being planted 3-inches from the wall!!

Really? Who thought it was OK to plant a full-size crape myrtle this close to a house??

(What on Earth were the builders thinking when they plopped the plant alongside the foundation originally? Did they get it mixed up with a dwarf crape -- although even that should have been planted at least a couple of feet from the wall. Or were they just being cruel and sadistic?)

This is a beautiful plant, but it's just in the wrong place. Even if it were a couple-feet away from the wall, that still wouldn't make any sense with this type of crape myrtle.

The lavender crape myrtle (Muskogee?) blooms are really beautiful. It's just a shame that the tree was planted so close to the house...

So unfortunately I think I have to commit real crape murder (not the crape murder that involves drastic annual pruning techniques).

My plan is to cut the plant down to the ground using loppers and a chainsaw.

From what I understand, crape myrtles don't die easy. Most likely, the plant will send up a thicket of suckers in an effort to survive.

Now many websites suggest drilling a hole into the trunk and pouring in concentrated herbicide, but I am reluctant to use such chemicals.

I thought I could try to dig out as many of the roots as possible and then regularly cut off any suckers that sprout. I imagine it might take a few years, but that the tree would eventually weaken and die.

What do you think? Is this a foolhardy idea? Should I bite the bullet and ask a trained landscaper to come over and remove the tree and/or inject poison into the stump?

Also...Should I be worried about a large Natchez crape (15-20 feet tall already) that is planted perhaps 4-feet away from another wall of the house -- again, that seems way too close to me.

Thoughts and advice are welcome!!

PS - I probably will also be removing 2 of the 3 crape myrtles that I planted just last year. One of those, Petite Snow, has not put on any new growth at all, nor has it bloomed this year. And the leaves do not even resemble the Petite Snow photos I've seen online, which makes me think that it might have been mislabeled.

The other crape that I'll be removing is called Geronino, from Flowerwood Nursery. There are two things that really tick me off about this plant:

New Geronimo crape myrtle leaves afflicted by powdery mildew are twisted and disfigured
New Geronimo crape myrtle leaves afflicted by powdery mildew are twisted and disfigured. Not what you want to see at the front foundation of your home .

1) I still have the tag that came with the plant where the size is given as 10-feet tall by 6-8 feet wide. Maybe that's a little big, but not too crazy for a corner foundation planting. But on Flowerwood's own website, Geronimo is now listed as growing 15-20 feet tall by 12-15 feet wide. So...basically I'm looking at another monster crape planted right against the foundation. No thanks. I'll dig it out this autumn while it should still (theoretically) be easy to do so.

Geronimo crape myrtle flower buds afflicted with powdery mildew
Geronimo crape myrtle flower buds afflicted with powdery mildew. Based on my experience with mildew on a different crape, these buds will not open.

2) If that was the only issue, I'd consider replanting the crape somewhere else on my property, but Geronimo also has major issues with powdery mildew, as you can see in the two photos above.

The thing that bugs me is that Flowerwood chose a Native American-sounding name for this crape myrtle. And it just so happens that many of the highest-rated mildew-resistant crape myrtle cultivars from the US National Arboretum (USNA) are known for having Native American names.

Texas A&M even says: "As a general rule, cultivars with name of a Native American tribe will be resistant to powdery mildew." Guess they'll have to revise that general rule now thanks to Geronimo. Caveat emptor!

Monday, August 12, 2013

Groundcover Review: Pachysandra procumbens, Allegheny Spurge

It ain't pretty. Pachysandra procumbens (Allegheny Spurge) has not covered ground, but rather revealed ground as the original stems have died off. 

Pachysandra procumbens, Allegheny Spurge


- Native to Tennessee and other parts of the Southeast. Hooray!

- Not particularly aggressive or fast-growing [especially when dead -- see photo above], ergo should be easy to control.

- Evergreen to semi-evergreen in zone 7 [when alive]. Hardy to zone 5.

- Supposed to have fragrant spring flowers, but I didn't see any this year.

- Reportedly can be propagated through division in spring or autumn.

- Has enough density and height (6-12 inches high) that it should be able to do a good job of controlling weeds [if not for the fact that it keeled over and mostly died].

- Attractive foliage [before it died].

- Supposed to have good drought tolerance ... although this did not seem to be the case in my garden. Maybe it has good drought tolerance in cooler and shadier climates such as the Smoky Mountains?

- Low maintenance. No need to remove last year's foliage - as with Sweet Woodruff it will simply collapse and be replaced with fresh new green foliage [unless it dies, in which case the foliage will not be replaced].


- Not tough enough to survive a Tennessee summer -- at least not in partial sun. Maybe it would do OK in full shade, but with morning sun and temperatures in the 90s, P. procumbens keeled over and (apparently) croaked. Well, I won't declare it down for the count just yet -- it may still rise like Lazarus next year -- but things are not looking promising at this point.

- Hard to find (unlike the widely-distributed and occasionally invasive Japanese Pachysandra - P. terminalis). You'll probably have to find a nursery or plant society sale that specializes in native plants or resort to mail order.

- Spreads rather slowly [when it survives...otherwise it does not spread at all].

- Reportedly needs partial to full shade, so not an option if you're looking for a groundcover for a sunny spot. Based on my experience, I'm thinking it needs at least a mostly shady setting in hot Southern climates.

Foliage is reportedly toxic to mammals. So please do not eat. On the bright side, this is probably why P. procumbens would be resistant to predation by deer or rabbits. (I think the same also applies to P. terminalis.)


Didn't cover ground. Didn't even cover the original patch of ground where I planted it. Disappointing. Cannot recommend based on my personal experience, but P. procumbens might work for gardeners with cooler and shadier environments than I could offer.

Monday, August 5, 2013

All Summer Long -- The Flower Parade Continues into August

Zinnia elegans, just one of a wide variety of self-sown volunteer zinnias in my garden in a dazzling variety of colors and shapes. Gardening books suggest deadheading zinnias for more blooms, but I rarely deadhead mine (since the goldfinches like to eat the seeds) and I still tend to get blooms for months! Zinnias are heat-tolerant and somewhat drought-tolerant, in my experience.

The foliage on one of the aquilegia plants was looking very tired, so I cut it all the way back down to the ground. From my experience in prior years, fresh new foliage -- seen here -- will soon emerge and make the plant look good as new. 

One of the two Black Chokeberries (Aronia melanocarpa) that I planted in spring 2012. This one is doing great, has probably tripled in size so far this year and is still pushing new growth. It gets morning sun and afternoon shade.

This is the other Aronia melanocarpa, also doing pretty well. It's bushier with more suckers pushing up, but it has not grown as tall. And if you look closely, you'll notice light dots on many of the upper leaves. I believe those are injuries caused by lace bugs. I typically don't spray any of my plants and this is no exception (although I did wash off the undersides of some of the worst affected leaves with a garden hose). I want to see if the Aronia can fight off the lace bugs -- hopefully with the assistance of some beneficial insects drawn in by the pests themselves and flowers like Sweet Alyssum that I've planted nearby. From what I've read, lace bugs don't usually cause the plant any severe damage, so I'm hopefully the Aronia will survive this indignity and emerge even stronger next year. 

Yes, like every other homeowner south of the Mason-Dixon, I have several crape myrtles. My favorites are the ones with white flowers like Natchez. I tend to find most of the other colors a bit too jarring and garish in the landscape. Plus in my experience, the white-flowered ones seem to attract the most bees! Anyway, like several of the other crape cultivars, Natchez has gorgeous exfoliating bark. I love both the older grey bark that's sloughing off and the ultra-smooth glowing new brown bark underneath.
Close up on Natchez Crape Myrtle blossoms

Cucumber-leaf sunflower (grown from seed), blooming its heart out for weeks and weeks!

OK, it can't all be pretty. This is/was a Salvia nemorosa (either May Night or Blue Hill...I planted them next to each other and never could remember which was which). Both plants bloomed too early to attract many bees. I trimmed them back as suggested to stimulate a rebloom. Instead, I seem to have stimulated their early demise.'s the other Salvia nemorosa. It's not totally dead yet. Just mostly dead.

Sunflower, taller than me (ergo taller than 6-feet)

Gaillardia pulchella "Arizona Apricot", attracts small bees, keeps blooming for months even without deadheading, even the spent flowerheads are attractive fuzzy balls. Technically perennial to zone 3, but it is not supposed to do well on heavy soils (like our clay), so I'm not counting on it to come back next year. But it is supposed to self sow, so hopefully I'll have some gaillardia regardless. And just in case, I'll probably try growing some from seed too. (This one was grown from a transplanted seedling purchased I believe at the Perennial Plant Society of Middle Tennessee plant sale.)

Not too many flowers here, but the foliage of this perennial geranium (x cantabrigiense "Biokovo") is looking great with barely any supplemental water all year in its first year in the ground.
Rozanne perennial geraniums are having their Best Year Ever. There are three Rozanne plants all mixed and rambling together. They too flower for weeks and weeks, especially when given afternoon shade. You can see that the plant is even pumping out fresh new (lighter green) foliage in August!

Yet another perennial geranium - Geranium sanguineum "New Hampshire". This one is throwing off a few flowers and lots of fresh green foliage. Beautiful!
Love the sky blue flowers on the Hardy Blue Plumbago (HBP). But why is it turning red so early in the year? That can't be a good sign... This one is in the sun and it's looking reddest (also doesn't seem to have grown at all from last year), but one of the two HBPs in partial shade is also reddening a bit. Hmmmm.... Has anyone else experienced this?

Lovely lemony flowers on the perennial sunflower Helianthus microcephalus (Small-headed Sunflower), "Lemon Queen" variety purchased just this spring at Gardens in the Wood of Grassy Creek. As with many of my other Gardens in the Wood purchases, this one has done great. This healthy, bushy plant is probably between 4-5 feet tall now. There are about a dozen flowers already open and many more buds. I'm guessing that within a week or two, this plant be covered with dozens of flowers. The bees and other beneficial insects are already happily visiting the flowers. I imagine the whole plant will be buzzing with activity very soon!

Don't be too grossed out, but what you're looking at here is a stem of the Lemon Queen perennial sunflower pictured above. You're probably wondering what the heck is that white foam at the stem junction? I was wondering too, so I looked it up and near as I can tell, it's probably the excretions of an insect called (for obvious reason) the Spittlebug or Froghopper. The insect sucks some sap from the plant and uses some of that sap to produce the foam to camouflage itself and protect it from predators. What do you think? Gross? Amazing? Clever? All of the above? Anyway, apparently spittlebugs usually don't hurt the plants on which they feed, so I've opted to pursue my usual policy of benign neglect, although I did use a hose to wash off some of the spittle one time to give predatory insects or birds a chance to do their thing.

Another sunflower? Not quite. This is a False Sunflower, Heliopsis helianthoides "Summer Sun" variety. Like many of the other flowers featured here, Heliopsis has been blooming for many weeks. Amazingly, the one slightly faded flower in the bottom left of the photo was the very first flower that opened and it's still looking pretty good! I haven't seen the Heliopsis attract as many bees or butterflies as the true sunflowers, but perhaps it's just getting overlooked right now? Although gardening guides say the plant can get up to 5-feet tall, it's probably only around 12-inches at the moment. It is a native perennial (hardy to zone 3), so perhaps it will get bigger next year? I think some Garden of Aaron readers have commented that Heliopsis self sows readily, so perhaps the bees will take more notice next year if I have a whole patch of Heliopsis plants for them to visit...

This is New York Ironweed (Vernonia noveboracensis). The foliage looks nice and I love the purple color of the flowers, but I have to admit I've been a little disappointed so far. The flowers are small, they don't seem to last that long, the spent flowers are not particularly attractive and worst of all, I don't think I've seen any bees or butterflies visiting the Ironweed yet. I've no intention of pulling the plant, but I am a little bummed that it has not attracted more pollinators yet. Again, as with the Heliopsis, maybe the problem is that I only planted a single Ironweed?

Similar issue here with the dwarf Joe-Pye Weed (Eupatorium dubium "Baby Joe"). I recently saw my first small bee on this plant, but I have not seen a single butterfly visit it yet, despite the fact that it is advertised as a butterfly magnet. I do have to admit that both the foliage and the pink flowerheads are very pretty though.

Another sunflower (Helianthus annus) bloom. I've got a lot of them in a variety of sizes and shapes. That's what happens when you plant a variety pack of sunflower seeds!
The older foliage on the Vitex agnus-castus is still looking great, but I'm excited to see the plant is having a flush of beautiful light green foliage. For some reason, I find these new leaves incredibly cute. I'm hoping the new leaves means that a second flush of flowers might be on the way. The bees - especially the bumble bees - went nuts over the earlier Vitex blooms, so I'm sure they'd appreciate a second round! 

Speaking of those earlier Vitex blooms, you can see the spent flowerheads here with their seeds forming. And camouflaged among the seeds is quite an interesting insect. Does anyone know what this? I imagine that it's predatory and is hiding among the seedheads waiting for an unsuspecting prey insect to alight?

Here's a mixed patch of Cosmos and Zinnias. As you can see, I love the casual and informal look of different colors all mixing cheerfully together.  

Let's finish up with the irrepressible purple coneflowers. Some of the petals are looking tattered, but these plants have been blooming for months, giving joy to countless bumblebees like the one on the right side of this photo. If you want to find a bumblee in my garden on a hot summer day, the best place to look would be on a sunflower or a coneflower.

I hope you enjoyed this little tour. I'll try to do another photo safari through the garden toward the end of September. Will the garden still be filled with flowers in another 6-8 weeks? Or will pathogens and pests get the upper hand? (Right after I took some of these photos, I noticed that powdery mildew is starting to run rampant through the zinnias.) 

Tune in next time - Same Bat Time, Same Bat Channel :)

Thursday, August 1, 2013

How Much Biodiversity Do We Need in Suburbia?

Knockout Roses have conquered suburban landscapes like this one. I have never seen a bee visiting a Knockout Rose - either in a photo or in real life. (Photo by mellowynk)

Douglas Tallamy thinks we need more biodiversity in our backyards (and presumably in our front yards too).

After taking a walk this weekend through my neighborhood and seeing the same 10-20 plants repeated ad nauseum (boxwoods, knockout roses and daylilies - oh my!), I'm inclined to agree.

Why does biodiversity or the lack thereof matter in the Grand Scheme of Things?

Tallamy makes the case that humans have taken over the vast majority of the land mass in the United States either for housing/retail/manufacturing or for agriculture.

To the extent that we then plant the land we've expropriated with grass and a smattering of (often exotic) plants that are useless to the native fauna, he argues that we are pushing many species toward extinction and thus impoverishing the planet.

Does the average suburban home landscape have any more wildlife value than a plastic tree? Note that plastic trees do not need to be watered or sprayed with pesticides. (Photo by BrickArt!san)

On my 90-minute early morning walk through my neighborhood last weekend, once I left my property, I saw exactly:

- 1 bee
- 2 species of birds (lots of mockingbirds, one goldfinch)
- 2 butterflies
- 1 coyote pup (very exciting!)

Do the yards in your neighborhood have enough biodiversity?

And how much is "enough" anyway? 

Should we set a goal that the average suburban property should contain 20 species of plants? 50 species? 100 species? What is the typical biodiversity of plant species on a 1/4-acre or a 1/2-acre of land anyway?

I don't the answers to all these questions, but I do think they are important questions to ask as gardeners in a nation where the population of humans continues to grow north of 300 million souls.