Cactus Blog

We Get Questions from people about their Euphorbias.

Hi there:
I am kicking myself that I was so blind to have probably missed this entire blighted side on this cactus before I bought it, just a few weeks ago. What is growing on it? Mold? Rot? Plaque? (I’ll break out a toothbrush! :-)) What can I do about it? I’ve attached a sad picture.

Thanks for any words of wisdom-
Amy

Amy,

You “cactus” is actually a Euphorbia, a cool succulent from Africa. It
actually looks more like sunburn, so I don’t think your blight is an
infection. My guess is your plant was greenhouse grown, under shady
conditions and when you brought it home the “north” side got turned
towards hot sun and the plant burned, just like we do on our first spring
trip to the beach…. The burn will eventually scar over and turn to
bark and the plant will keep growing, but it will always have a scar.

Take care,
Hap

2) Attached is also a photo of a prickly pear we purchased from Cactus Jungle. We are unfamiliar with these plants and are wondering if the new growths shown in the photo are new pads and if so, how will we know when we are getting fruit instead of pads. As well, is there a cycle for when new fruits typically emerge?

Many thanks!
Beth M

Beth,

Number 2) Your Opuntia does look like it is growing a nice crop of pads.
Young flower-sprouts look very similar but look more like spear-points
when they first sprout. Your plant should bloom over the late spring and
summer, but you can encourage flowers by giving it some “Bloom”
fertilizer (a fertilizer with a high middle number like “4-16-3″. We use
Fish Bone Meal as a nice slow release Bloom Fertilizer or for faster
results the liquid “SaferGro”.

Take care,
Hap

Hello,

We have two questions below:

1) Attached is a photo of a plant you put in one of my existing pots. It is blooming beautifully and seems quite happy. However, it does appear that it will soon outgrow the pot. How shall I go about re-potting this plant?

2) [2nd question edited for later blogging]

Many thanks!
Beth M

Beth,

1) The Calandrinia is fine in that pot for several years. It will get
bigger, and bloom more boisterously as it does. If it gets too
rambunctious prune it back a bit. Just cut the stems where you want it
to re-sprout. You can save the cut pieces and plant them in dry soil and
they should root and start growing in a month or two. If you want to
repot to something larger, rather than pruning, run a garden knife
around the edge of the pot to loosen the root ball. Then ease the soil
and roots out and move carefully to a larger pot and add soil in around
the existing root ball. Calandrinia have very fragile roots so handle
with care, but even if most of the roots break off it will reroot,
though it will set in back a few months.

Hap

Q: We planted this cactus over 10 years ago, and the other day were surprised to see a stalk growing out of it. Do you know what types of cactus this is? And is it likely to ever do this again? We live in San Carlos. I would be interested in getting another one.

Many thanks!
Colleen

A: Colleen,

Your “cactus” is actually a Yucca, most likely Yucca whipplei (a wonderful California native) or perhaps Yucca rostrata. They look very similar and there is not enough detail in you photos for me to be sure… however my guess is yours is Yucca whipplei. If it is, this bloom will be it’s last, as the rosette that blooms dies after it is done blooming and hopefully setting seed (like it’s relatives Agave’s).

It will sometimes “pup” around the base and those will grow in to replace the “mother” rosette, but not always. If it is Yucca rostrata, it will not die, but will grow several new rosettes and eventually become a multibranched tree yucca and will bloom again when it has enough energy stored up to do so. Either way yours is a great looking plant and congratulations in getting it to bloom! It should bloom over the next few months and will look spectacular!

Take care,
Hap

From the Contra Costa Times, we get more of Ruth Bancroft’s answers, plus a picture too.

Sempervivum hybrid (Becky Rice/Ruth Bancroft Garden)

Q: I have a patch of little hen-and-chicks in my garden (this is what I have always called them, though they came labeled as Sempervivum) with an appealing purple color. Some of the heads do not look right, and seem to have a sticky substance on them. What could cause this?

A: Sempervivums, with their clustering habit and neat little rosettes, are popular garden plants. Coming from the mountain ranges of Europe, they are very cold-hardy, but they are also prone to attack by aphids, as you have discovered.

These small sucking insects secrete a sweet sticky substance that often attracts ants. However, aphids are not hard to combat, without the need for toxic chemicals. Simply keep a spray-bottle of Safer Soap handy to spritz the affected plants.

Note that another group of rosette-forming succulents from Mexico, the Echeverias, share the common name “hens-and-chicks.”

The subject line of this question was “My Barrel Cactus” so that’s how we knew what the question was about. There was no photo, so we had to make some assumptions. Photos are always good. Anyway, on to the question.

Hi,

I have cactus that that has been dying from the base up and turning and orangish yellow. I am wondering if there is anything i can do to save it. Someone told me that you can cut the cactus off above the dying part and then replant it. Can you do this? What do you have to do in order for the cactus to survive if you do this?

Thank you,
Mike

A: Mike,

It is possible to save a cacti by cutting off the top un-infected part and then re-rooting. On barrel cactus it is very hard to pull off since they are so big around so it is hard for them to heal. To make the attempt cut above the infection, take a look at the exposed soft tissue and make sure there is no sign of infected tissue (orange, red, brown or black spots), if there is clean your knife in bleach and try cutting higher up. Once all there is is clean green tissue coat with household hydrogen-peroxide to disinfect and to speed up the “callusing”. Let the cut heal in dry warmth until it is scabbed over by what looks like a well scabbed skinned knee after a bike crash…. Then place the plant in dry cactus soil to grow new roots. Do not water until there are signs of roots, six to twelve weeks. You can mist the barrel a little at night (when it’s stoma are open) to give it some water. Keep it warm and in bright light but not in full sun.

Good luck,
Hap

[ed: good luck indeed.]

Sometimes we get questions about sick agaves and they’ve sent along a picture too.

hello Hap,

i met you at your store a few weeks ago…i have a sick agave that i was hoping you could diagnose. per your suggestion, i have attached some pictures. as you will see, the leaves seem to be splitting. we have really poor, clay soil here in San Rafael. We just amended the soil today and moved it to a new spot in our yard.

Any advice you have on what else needs to be done would be very much appreciated.

Thanks so much.

-Sally

Sally,

It looks like your agave took some winter wet/frost/freeze damage. Moving and improving drainage will help a lot. They can usually handle the cold if they have dry feet(roots) and leaves. You can clean the infected areas with household Hydrogen-peroxide which should help them fight off the fungi. The Damaged leaves will always look bad but given time it should grow enough new leaves that you can cut off the older damaged one.

Good Luck,
Hap

Q: Hi Peter,

Wondering if running the tillandsia under water till it’s all wet is enough, or does it need soaking? I’m doing this twice a week, and it’s cohabiting with a cymbidium under the eaves on my deck.

It’s like having a pet - I can bring it in for a bath, talk to it, walk it around & put it back or put it anywhere else! What fun.

I’ll get some liquid kelp too.

Phyllis

A: Phyllis,

The key to growing tillandsias is what you say when you talk to them. I prefer to read to them from Vonnegut.

Running it under water twice a week is enough - it doesn’t need to soak but once a month with the kelp.

You can even mist it 3 times per week, or leave it in a bathroom where it gets light misting every day.

It’s all good.

Peter

Q: Dear Client Support, [ed: Woohoo! someone finally addresses a letter to us using our real name!]

I was wondering if there was a preferred air/soil temperature range for overwintered plant varieties such as Echeveria and Graptopetalum. I wasn’t sure if temperatures should be in the vicinity of 35 to 50 degrees for dormant plants, while Aeoniums, Haworthii, ect. should be temporarily provided warmer temperatures (above 60 degrees) during their growing phases in the fall and early Spring.

I also wanted to know if plants in dormancy should only be watered when either their leaves or root systems exhibit a certain degree of dehydration.

My thanks for your time and efforts in the matter.
Sincerely,
Joe

A: Joe,

Echeveria and Graptopetalum need to be kept above freezing and the colder it is, the drier they should be kept. Between 35 & 50 degrees they should be watered only once every 4-6 weeks, though again if it is very cold keep them dry. They need to concentrate the sugars in their leaves to keep from getting cold damage. Winter growing succulents do need more water in the winter since they come form locations that get most or all of their rain in the winter months. Our winter growers are outdoors year round and usually get down to the upper 20’s over night now and then. If it is expected to get that low we usually cover with frost blankets, though some have dealt with 25 degrees just fine.

Hap

Q: Hi. I called your store last weekend and had some questions about a cereus cactus I have that appears to have scales but also seems to be “dying” from the top down. I was told to email some photos of my plant, so I’m sending them now. I would really appreciate your looking at them and advising me of what I can do to salvage my cactus. If you have any problems accessing the pictures, please let me know.

Thank you very, very much for your time and assistance.

Sincerely,

Jenny

A: Jenny,

It looks like your plant has both scale insects and an infection, viral or fungal (most likely brought on by the bugs…). You should spray with Neem Oil to kill the scale. You can then clean off the dead ones with a small paint brush dipped in rubbing Alcohol. For the infection, I hate to say it but you need to cut off the top a couple of inches below the “icky” part and then look at the cut part to make sure there is no black or orange spots in the soft tissue, if there are you need to clean the knife with alcohol and re-cut lower down until you only have clean green tissue showing. Then pour household Hydrogen-Peroxide over the cut to sterilize. Do this again for the next few days to make sure the infection is dead.

It will scar up and then branch around the cut and in a few years it won’t be that noticeable.

Good Luck,

Hap

Sometimes we reply to people’s questions even though we really don’t have an answer for them. And then I post them so the whole world can see my failures. Like this one:

Q: Good Morning. My name is Jennifer & I live in Wylie, TX a suburb of Dallas. I am interested in installing a cactus garden in my front yard, but I honestly don’t know anything about cacti. I searched online to try to locate a local landscape designer, but haven’t been able to find any that specialize in cacti and succulents. Do you happen to know anyone in the Dallas/ Fort Worth area?

Thanks in advance for your assistance.

Jen

A: Jen,

Sorry but we don’t have any good landscaping contacts in the Dallas area. You might want to try the Texas chapter of the Cactus and Succulent Society.

Peter

They Get Questions that are answerable with the application of a good dose of California Natives. The San Luis Obispo County Master Gardener tells all:

We Get Questions about pests, yes we do.

We ask people to send us photos, and they do, boy do they.

Q: cactus jungle,

here are the pictures. please note the white dots in the picture. what causes these? (lack of light or water, too much light or water?). also given the size of the smaller cacti, should any of them be transplanted to their own pots or can they all live together in the same pot as shown in picture 2 [not shown]? how much water should they be given being that they only get about 2-3 hours of direct sunlight? thanks for your help!

-jon

A: Jon,

Thanks for sending the photos, they are quite clear: your Pachycereus has scale, an insect that attaches itself to the plant and sucks the juices out. This is treatable.

1. Spray the plant with neem oil to kill them. We mix 100% neem oil, which is safe for cacti. Don’t use the 70% solutions, like “Rose Defense,” which are not safe.

2. After 2-3 days, carefully clean off the scale with a q-tip dipped in alcohol.

Finally, your plants are all fine in the same pot, but they need more sun. Not enough light is making them prone to the scale. Slowly bring them into a location that gets more direct sun, waiting a week after they’ve been treated. I recommend a minimum of 4 hours of afternoon sun, which means near a west or south facing window.

Water every 3 weeks, drenching the soil and letting the water drain away. You should lift the pot up on pot feet or bricks so it is never sitting in water in the saucer.

Good luck,

Peter

The Ruth Bancroft Garden has a new entry garden. Ruth Bancroft answers your questions about her gardens in the Contra Costa Times:

Q: We like the look of your new garden alongside the gate on Bancroft Road, and we would like to do something similar in front of our house. Can you offer some tips?

A: Our entry garden is officially called the Lloyd Davis Entry Garden, after the late Lloyd Davis of Orinda, from whom many of the specimen plants came that were used in creating it. It features an array of cacti and succulents with a covering of gravel spread on the ground between them. This gravel is called “¾-inch Lodi” and came from Mt. Diablo Landscape Center in Concord.

You’ll have to read the rest of the article to find out her advice for replicating this garden at your home. I don’t want to spoil the surprise ending.

We sometimes get questions that we have never gotten before. Like this one:

Q: Hi,

I have a bunch of cacti that I keep indoors (I live in NJ.) I have a large yucca species that has developed an infestation of tiny centipedes in the soil. How do I get rid of them without killing the plant?

Any suggestions would be helpful.

Thanks,

Anne

A: Anne,

Centipedes! Really, now. We recommend a soil drench with neem oil. It’s also sold as rose defense, which will work fine as a soil drench, but don’t spray it on cacti since they need 100% neem.

Peter