August 2009 - The Arboretum
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Cactus and Succulent Show Highlights

Held by three local cactus and succulent societies, the InterCity Cactus and Succulent Show drew hundreds of aficionados of these plants to Los Angeles County Arboretum & Botanic Garden. Collectors of these weird and wonderful plants brought their most prized specimens to the event to compete for ribbons and medals. Let’s take a look at some of this year's entrants:
Adenium obesum subsp. swazicum, commonly called the ‘Desert rose,’ is an African plant related to oleanders and garden vinca. It is summer deciduous, losing all its leaves in the summer and relying on water and nutrition stored in its caudex, the large fleshy structure that appears as a mass of swelling roots at the base of its stem. Plants with a caudex are referred to as ‘caudate’ and are much in demand by collectors because of their monstrous,  unusual nature and because they are fairly easy to grow in containers. 

Aztekium ritteri is native to a single valley to the state of Nueva Leon in northeast Mexico where it is found growing out of almost vertical limestone and gypsum cliffs. Its genus name comes from its resemblance to the stair-stepped structure of Aztec temples. It is thought to be one of the slowest growing cacti on earth. 

Cyphostemma seitziana is a pachycaul succulent, a type of caudate plant that has a swollen stem that appears as a bottle shaped structure. It’s found in Namibia where it grows in desert areas.  It produces small flowers followed by fruit, but be careful, even though Cyphostemma seitziana is in the same family as table grapes, the fruit are poisonous to humans and animals. 

How to Spend More Time on MySpace, Less Time on Your Place:  Moving to a Low Maintenance Garden.

Dear Arboretum Plant Info, As my wife and I grow older we’ve found that spending the time out in the garden necessary just to keep things looking decent takes a lot out of us. Instead of spending time in our garden exhausting ourselves weeding, pruning, and cleaning up we’d rather spend it chatting with our grandchildren on the internet. What can we do to make our garden “low maintenance”? Signed, Facebook Grand-DadDear FBGD, I assume you can’t pry your grandkids off of their computers for an afternoon of gardening with grandpa at your place; so in lieu employing your loved ones as day laborers I would suggest the following:

Replace your lawn with a low water use groundcover.

Replace all 'out of scale' plants or plants that require pruning to make them look good with smaller scale plants that do not need pruning. This will prevent weeds and cut down on weeding. Ideally the mulch layer should be at least 3 inches thick.

Be sure to add new mulch at least every year. Note: This mulching routine might fail if you have a landscape of California natives. These plants are adversely affected by organic mulches because of the nitrogen formed when the mulch breaks down. California natives prefer inorganic mulches like gravel or decomposed granite. 

Increase the amount of 'hardscaping' and unplanted areas in your landscape; fewer plants, less maintenance. 

Mulch with shredded bark or other slow decaying organic materials.  

Use low water use plants, they grow slower so they don't need as frequent pruning as higher water use plants.

Do not fertilize. Broadcast fertilization isn't necessary for even high water use landscapes. There are individual exceptions, though (fruit trees, roses, azaleas, etc.). Adding nitrogen to plants makes them grow faster, thus you have to prune more.

-Arboretum Plant Info

How To Control Your Neighbor’s Passion (vine)

Dear Arboretum Plant Information,Last year our neighbor planted passion fruit vines on his side of a retaining wall that separates our properties.  They’ve been very prolific and are constantly climbing over the top of the wall and onto our side. We politely asked him to keep the vines trimmed, which he did, but our problems still weren’t over. Early this month we noticed a few young shoots popping up on dry hard compacted dirt on our side of the wall & in the cracks of a bricked patio floor which is flush against the wall.  I tried using Roundup Weed & Grass killer a few times (streamed & foamed during some 80-mid 80 degree sunny weather) & later noticed that they were still growing (i.e. green & thriving).  Initially the portion above soil seemed to die, but after a week, the shoots came back.  I haven't sprayed any more since then & am waiting to let them grow long enough to match the growth on our neighbor's side. How do I get rid of these plants? Signed,  Passionate in PasadenaDear Passionate,What’s probably happening is that the vine is sending out shoots from its roots. Spraying Roundup seems like a good idea, but it does present some problems:

Treating the shoots may kill your neighbors vine. Since the shoots that you are spraying are basically the same plant as your neighbors, spraying an herbicide like Roundup that is absorbed by the entire plant before it starts to work could result in not only the shoots you are spraying dying, but your neighbor’s entire vine dying as well.

Roundup takes a couple of weeks to show results. You’ve just sprayed these plants, give the Roundup some time to work.

Applying Roundup when it’s too hot will result in the plant’s tissues burning. Scorched plant tissue does not absorb Roundup, so the plant does not perish. You should apply roundup when the temps are below 85 degrees F.  Preferably in the early morning when temperatures are low and any breezes are at a minimum. Errant exposure to Roundup spray can cause plants like roses to become deformed; even from minute amounts of Roundup.

Treating expanding shoots with Roundup can be futile; this is because the flow of nutrients in the plant (Roundup has to be taken up into the nutrient stream to be effective) should be in a direction towards the roots for Roundup to be effective. A newly expanding shoot has little capacity to make food, its expansion fueled by a nutrient flow with a net direction towards the tip of the shoot. So what you need to do is allow the shoots to grow until they are about a month old, and then spray them when temperatures are below 85 degrees F.  This is because after a month the ability of the plant to make food for the plant is much higher than when it first started expanding and therefore an effective dose of Roundup will be delivered to the entire plant…which, like I mentioned above, may include your neighbors plant too.  

So, how do you get rid of the shoots if you have decided you don’t want to kill your neighbor’s passion and not to use Roundup? Simply snap off the new shoots as soon as they appear.

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© 2019 Los Angeles County Arboretum and Botanic Garden • 626.821.3222 • 301 North Baldwin Ave, Arcadia, CA 91007

© 2019 Los Angeles County Arboretum and Botanic Gardens

Phone: 626.821.3222

301 N. Baldwin Ave, Arcadia, CA, 91007