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Watch How You Water!

OK, we all know that succulents are low-water plants. But they’re not “no-water” plants. Although they may survive without irrigation during the heat of summer, they’re unlikely to be lush and healthy.

I suggest that you ~

— Check your automatic irrigation system. Trust me, it needs it, and maintaining it can mean life or death to prized plants. Watch for leafy growth blocking sprayers, clogged riser heads, and plugged drip lines.

— Pay keen attention to soil moisture during heat waves and desiccating winds.

— If the root zone goes dry, supplement auto irrigation with hose watering. (See my canary-in-the-mineshaft way to evaluate evaporation in my latest video, Succulents, Sun and Summer.)

— Water early in the morning or late in the day. Note to desert gardeners: Watering in midday heat can literally cook roots. (Eek!)

— HOWEVER, aeoniums, dudleyas and other succulents that have closed their rosettes should be watered minimally or not at all, lest dormant roots rot. The plants will revive when the rains return. (They may not make it until then, though, if in full sun. So, shade them.)

— If the ground is concrete-hard, leave a hose dripping overnight to create an underground cone of moist soil.

— Trees and shrubs want water where their canopies would naturally direct rainfall: around the perimeter of the plant.

— Add gravel topdressing around succulents (or use organic mulch for woody plants) to help hold moisture in the soil.

— Take the opportunity, when hose-watering, to blast pests, fallen leaves and dirt out of leaf axils and the centers of rosettes.

— Use a hose-end sprayer—ideally one with multiple settings—to direct water where you want it.

— A hose lying in summer sun may contain scalding water. You already know this, but your house-sitter may not, so be sure to mention it.

— If you have a hose-full of hot water, aim a fine spray skyward. Droplets will cool by the time they hit leaves.

What about potted succulents?

From my website’s FAQ’s:  Aim to keep soil about as moist as a wrung-out sponge. About once a week should do it. Water thoroughly to soak the roots and flush salts. Let common sense prevail: Water more during hot, dry spells and less or not at all during periods of high humidity, cool temperatures and rain.

ALSO SEE: Page 56 of Succulents Simplified, pp. 219-222 of Succulent Container Gardens, and pp. 134-135 of Designing with Succulents (second edition). 

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Summer Care for Your Succulents

Don’t let midsummer heat, sun and dryness damage your succulents! 

If you live in an arid climate and grow succulents in the open garden (as I do), I recommend you ~

— Watch and enjoy my latest video: Succulents, Sun and Summer. On an 89-degree day I give a tour of my garden, noting what’s in bloom, lookin’ good (or dreadful), and checking the health of succulents small and large.

— Move sun-sensitive potted succulents into the shade: haworthias, gasterias, euphorbias, faucarias, sansevierias, echeverias, and anything light-colored or variegated.

— Give aloes and crassulas enough sun to turn bright colors but not so much that leaf tips shrivel or burn.

— Shade horizontal stems of trailing aloes, senecios, othonna and the like. Sunburn hinders stems’ ability to transmit moisture from roots to leaves.

— Create temporary shade structures from old window screens.

— Or use leafy branches trimmed from trees (insert in the ground next to a plant you want to protect, on the side that gets the most sun).

— Evaluate garden areas in need of shade, and plant trees when the weather cools in the fall. And for that (drum roll) I have another new video: Twelve Low-Water Trees for Succulent Landscapes.

How to Fertilize Your Succulents

It’s Spring!
Time to Feed Your Succulents

Fertilize succulents when they’re emerging from dormancy and beginning their annual growth spurt, which for most is spring. A light feeding of manure tea, diluted fish emulsion, or a balanced fertilizer will help them grow lush and lovely. See my video. 

Link to video of Debra video about fertilizing succulents

What do I use?

For container-grown succulents, one Moo Poo tea bag per three gallons of water, steeped overnight.

Uh…”Moo Poo?”

Yes. Otherwise known as Authentic Haven Brand Soil Conditioner, Premium Manure Tea. (Btw, I’m not getting paid to endorse it.)

What about in-ground succulents?

I apply Ironite before a winter rainstorm (I know, it’s too late) and a balanced granular fertilizer in March.

How to apply?

Water the plants, then pour manure tea until it begins to run out the pot. In the garden, spread granular fertilizer and water it in.

What kind of granular fertilizer?

The brand doesn’t matter, but the ratio of N (nitrogen), P (phosphorous) and K (potassium) should be equal.

How much?

Succulents need about half the dose recommended on the package.

Is there an organic alternative?

Apply a topdressing of compost. I like fish emulsion, too, for both pots and in-ground plants (diluted half strength).

How often?

Once in spring when daytime temps stay above 60 degrees F. Then again in June.

What if I don’t feed my succulents?

No biggie, but they’ll look and perform better if you do.

Is it OK to fertilize more frequently?

That’s what many growers do. A little bit of fertilizer with every watering promotes rapid growth. However, such plants are considered “soft” (a nursery term) rather than “hard,” meaning tough. It’s a trade-off. I grow my succulents hard to help them endure the vicissitudes of the open garden.

Anything else?

Soils vary from region to region and even within a garden. The best way to know what your soil lacks is to have it tested, but it’s common sense that succulents growing in, say, oak leaf mulch are getting ample nutrients and don’t need fertilizing; those living in pots for years or growing in decomposed granite probably do.

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Post-Rain Must-Do’s for Succulent Gardens

When is rain TOO much rain?

We’re not used to so much rain here in Southern CA. One series of storms has followed another. I’ve been gleefully gathering buckets of fresh rainwater for my potted plants. Could the drought finally be over? Well, no. It’ll take hundreds of years for underground aquifers to refill. The snowpack isn’t adequate for our future water supply. On the bright side, our gardens are looking glorious. Even those with mainly drought-tolerant plants.  If drainage is adequate, annual rainfall less than 25 inches, humidity is low, and temperatures remain above freezing, your succulents should be fine.

Check for:

Succulents with rotted leaves. Remove mushy leaves before rot spreads to the plant’s stem or crown. This and other concerns are addressed in my YouTube video, Oh No! Something’s Wrong with My Succulent! 

Drainage issues. If soil stays sodden and muddy areas remain long after a storm, roots may drown. Move plants to high ground, and install French drains.

Slope erosion. Create dams of rocks and diversion channels, and add gravel or mulch to diffuse the rain’s impact.

Stagnant water. Check pots, bins and barrels. If they’ve filled, dump the water before mosquitos find it and breed.

Weeds. Wherever soil is exposed to sun, weeds WILL sprout. Get them when small. All too soon they’ll have deep roots, go to seed, and look you in the eye.

Seepage. Check your home’s basement. Mine used to have an inch or two of standing water whenever the ground became saturated during storms. A few years ago, a friend suggested a simple solution: Coat the concrete blocks that form the basement’s walls with a special paint that prevents seepage. Works great. Any home improvement store carries it.

Shop for plants.  Now’s a good time to accumulate plants you want to add to your garden. Rain-soaked ground is soft and easy to dig. Early spring is the best time to establish new plants, after all danger of frost has passed (here in Southern CA, that’s usually by Valentine’s Day, but you may want to wait until March just in case). Plants will take off in spring and won’t have to contend with summer heat while putting down roots. And if your garden is like mine, when the soil dries, it’ll be as hard as concrete.

Take photos as reminders. When the weather clears, such issues are easy to forget.

View my video: Post-Rain Must-Do’s for Succulent Gardens Debra's post-rain must-do's video

The bottom line: Succulents are opportunistic when it comes to rain. They absolutely love it. My own garden looks better than ever. I hope yours does too!

How to Protect Succulents from Frost

Frost cloth protects jades and other vulnerable succulents in my garden

Frost cloth protects jades and other vulnerable succulents in my garden

Depending on the type of succulent, how low temperatures drop (water freezes at 32 degrees F), and how long the cold snap lasts, “frost tender” succulents may show damage just on leaf tips or collapse into mush.

When moisture in the cells of a vulnerable plant freezes, it expands and bursts cell walls. A few succulents have a built-in antifreeze, and survive temperatures well below 32 degrees F—below zero, in fact. But these are the exception, and tend to be in the genera Sedum and Sempervivum.

Crassulas, aeoniums, euphorbias, and kalanchoes are among the most tender succulents. The majority of aloes, echeverias, cacti and agaves can go a few degrees below freezing for a short period.

Unlike most agaves, thin-leaved Agave attenuata is the canary in the mine shaft where frost is concerned. After a brief exposure to 32 degrees, it looks like this.

Unlike most agaves, thin-leaved Agave attenuata is the canary in the mine shaft where frost is concerned. After a brief exposure to 32 degrees, it looks like this.

Check the forecast, and if there’s a frost advisory for your area, cover susceptible plants with frost cloth (sometimes called garden cloth, frost blanket or floating row covers) or old bedsheets.

When determining if a tender succulent needs to be covered, I sometimes stand over it and look up. Plants beneath eaves or tree branches are not as vulnerable as those open to the sky.

Cold air is heavier than warm, and flows down slopes and collects in low spots. Consequently, succulents in swales are more at risk than those atop berms.

You may have heard that Christmas lights raise the temperature a few degrees. Yes, if they’re the old-fashioned kind. Those sold nowadays (LEDs) don’t generate heat.

Wait until spring to trim damaged tissue. It’ll help protect the plants from further damage.

Watch how I cover my own tender succulents in my new video, “Protect Your Succulents from Frost.”

Agave beetle
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Agave Snout Weevil Prevention and Treatment

 

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Agave snout weevil is a half-inch-long black beetle with a downward-curving proboscis that enables it to pierce an agave’s core, where it lays its eggs. Grubs hatch, consume the agave’s heart, then burrow into the soil to pupate. The weevil (Scyphophorus acupunctatus)—once prevalent only in desert regions and Mexicois spreading rapidly throughout the US and abroad, earning it the dubious distinction of being one of the “Top 100 Worst Global Invasive Species.”

Agave snout weevil

An agave’s grub-eaten core resembles a sponge.

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According to the Global Invasive Species Database, “Scyphophorus acupunctatus is becoming a major pest of native Agavaceae and Dracaenaceae species worldwide. Native to Mexico, it has decimated populations of Agave crops there, in particular species used in the tequila and henequen industries. The importation of ornamental Agave plants worldwide has facilitated S. acupunctatus to establish in many parts of the world, particularly in Central America and the Caribbean, in Africa, Asia and South America.”

Is your agave infested? Look for damaged tissue where leaves meet stem. The lowest leaves will appear wilted, and may slope unnaturally downward while the center cone remains upright. The plant, no longer anchored by roots, will rock when pushed. When an infestation is well underway, it’s possible to push the agave over onto its side. It’ll break at soil level, revealing a mushy, foul-smelling core infested by plump, squirming, half-inch, cream-colored grubs with brown heads.

PamPenick_AgaveWeevilLarva_R

Nursery stock may be infested, so from now on, plant agaves bare-root. 

Succulent collector Jeanne Meadow is well versed in pests that affect her plants. She has a large succulent garden in Fallbrook, California, halfway between Riverside and San Diego. Jeanne says people tend to assume nursery plants are pest free, yet that’s the main way snout weevil enters gardens. The beetles can’t fly (there are such things as flightless beetles).

When an agave in her garden shows signs of infestation, Jeanne removes it and every plant for several feet surrounding it. Then she sifts the soil and picks out grubs and beetles. “It’s a huge undertaking,” Jeanne says. “Fortunately they’re slow crawlers.”

Snout weevil hasn’t stopped Jeanne from bringing home new agaves. Before planting, she removes an agave from its nursery pot, sets the plant (root ball and all) in a wheelbarrow, and hoses the soil off the roots. She examines the plant for beetles and puncture holes, and the soil for grubs. If a plant is infested, she destroys it and informs the source nursery. She notes that when chased, weevils head to the agave for shelter. “They don’t try to escape from the wheelbarrow.” Incidentally, after observing grubs kept alive in soil-filled jars, Jeanne says that when deprived of an agave to feed on, grubs don’t pupate (turn into weevils).

Note: Jeanne plants ONLY bare-root agaves. 

What about insecticides? Although neither Jeanne nor I advocate commercial insecticides, we agree that the responsible thing to do is to prevent the beetle from spreading. “This is an emergency situation,” Jeanne says. “The pest is spreading like crazy and has to be brought under control.” At the first sign of infestation, she drenches the soil around the agave with an insecticide that has Imidacloprid as the main ingredient. One brand, available on Amazon, is Compare-N-Save Systemic Tree and Shrub Insect Drench.

Insecticide drench

 

In my YouTube video, “Agave Snout Weevil Prevention and Treatment,” I demonstrate how to inspect nursery agaves, show resistant varieties, and interview agave expert Kelly Griffin at an infested colony of Agave americana. 

Kelly mentions applying a systemic insecticide as a prophylactic (preventive) option. If you want to do this, it should ideally be applied twice a year, in early and again in late spring, when the beetles are active. If you use the Compare-N-Save drench, go with the ratio for shrubs: 3 oz. per foot of height per gallon of water. Soak the soil the night before to help penetration. It’s best not to use it in summer as high temperatures may diminish its effectiveness and it may even harm plants already stressed by heat.

Systemics, as the name implies, spread insecticide through a plant’s system, so any bug that ingests it dies. But a systemic may not prevent the plant from being irreparably damaged, because…

It’s not the grubs that kill the plant by consuming its center core, it’s the bacteria that the weevil injects into the plant. The weevil is a vector (carrier) of Erwinia carotovora, a micro-organism that softens the tissues, so its grubs can easily consume it. After chewing into an agave that has been treated with a systemic, a beetle will likely die, but the insecticide won’t kill the bacteria that the bug introduced. If your goal is to kill snout weevils before they spread, a systemic ought to do it. But if you have one or more agaves you want to protect at all costs, a systemic drench is no guarantee they won’t decline.

Green alert: Insecticides kill beneficial insects too, and can disrupt your garden’s natural predator-prey balance. Birds and reptiles eat snout weevils, which have coexisted with agaves for millennia. Personally, I like the idea of my garden’s lizards feasting on the grubs, which look like meal worms sold in pet stores. However, even more, I like the idea of doing my part to prevent the beetle’s encroachment into my neighbors’ succulent gardens and beyond. So, with reluctance, I’ll drench my agaves if and when I see a snout weevil in my garden, or even a hole indicating that the pest has arrived. And I suspect it will, because several large Agave americana ‘Marginata’ in my neighborhood have succumbed to the pest.

If you don’t want to use inorganic pesticides, remove an agave at first sign of infestation and don’t plant agaves in that part of your garden again. Consider replacing them with aloes, which are unaffected by the weevil. Btw, one organic control currently under development is a pheromone trap designed to attract adult beetles in search of mates. Weevil-resistant Agave varieties also are being selected and bred, but it may be years before a good supply is widely available.

Update: Kibby Mayo of Oregon responded on Facebook that she’s “found using Beneficial Nematodes to be effective in preventing and treating these infestations.” Basically, the nematodes kill insect larvae. Unfortunately, I’ve not been able to find a way to contact the manufacturer (Flagline) to ask if it’s effective against snout weevil.  Nematodes that eat grubs

 

CRW_1686_A_r

Plant agaves only in pots. In areas where snout weevil is known to be active, plant agaves in containers, like the urns shown here. Potted agaves are more difficult for weevils (because they don’t fly) to access, you can easily get rid of infested soil in case they somehow crawl into the pot, and you know that the soil is OK in the first place because you put it there. Additional advantages to growing agaves in pots is that it elevates the plants for better viewing, enabling them to serve as garden focal points even when small. Moreover, potentially immense, pupping agaves (such as A. americana species) stay small in containers, which also serve to corral their offsets, preventing them from popping up elsewhere in the garden.

Which agaves are susceptible and resistant? The snout weevil seems to prefer Agave americana (especially mature ones and variegates), but will go after other Agave species. It seems to stay away from agaves with soft leaves, such as Agave attenuata; those with tough, hard-to-pierce leaves (such as agaves ‘Sharkskin’ and victoriae-reginae); and those with slender, nonjuicy leaves such as A. bracteosa and A. filifera. Unfortunately, it also infests other genera in the Agavaceae family, such as Nolina, Beaucarnea, Yucca, and Furcraea. It reportedly attacks Mexican fence post cactus (Pachycereus marginatus) and possibly barrel cacti.

A postscript from Jeanne Meadow: “The snout nose shouldn’t discourage anyone from planting agaves. There IS hope, and my garden is a great example of that.” She notes, too, that the insecticide drench—which degrades over time—has had no negative impact on her garden’s overall health and ecosystem, including its population of beneficial insects, reptiles, amphibians, etc.

More info:

UC Nursery and Floracultural Alliance Regional Report, Spring 2016, “Agave Pests

Global Invasive Species Database

Desert Botanical Garden, Phoenix, AZ

Pam Penick’s blog post: “Evil Weevils! Agaves Under Attack in Austin”

Tropical Texana blog: http://tropicaltexana.blogspot.com/p/agave-weevil-eradication.html

View my 7-minute YouTube video, “Agave Snout Weevil Prevention and Treatment.”

Succulents and Too Much Rain, A French Solution

I like how the Jardin Zoologique Tropical in southeastern France keeps their succulents from becoming waterlogged during seasonal rainstorms. Corrugated fiberglass panels atop metal bars tent the plants so excess rain doesn’t soak the soil.

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The structures are tall enough to allow good air circulation, and the panels are translucent, enabling maximum sunlight to reach the plants. The covers, which have a horizontal metal rod atop them so wind can’t lift them, also protect tender succulents from frost.

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Notice, too, that the plants grow in rocky, elevated, sloping soil, so water drains away from the roots.

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You might do something similar in your own garden with a patio umbrella secured in a concrete base. But keep in mind that the water has to go somewhere. The French garden’s panels channel rain onto the gravel roadway nearby.

Btw, this public garden, located near the village of La Londe-les-Maures, is deservedly proud of its succulent collection. Here’s a description from the website, courtesy of Google Translate. The common names of the plants are charming.

Our plant collection is rich in many varieties of succulent plants: agaves, aloes and euphorbias. Every season their blooms transform the gardens. We regularly introduce little-known species and observe them for their ornamental potential. Perhaps the best known are cacti native to the Americas. We grow several species hardy in our climate. Some are globular, like the famous “mother-cushions,” others are elongated, cylindrical and commonly called “candle cactus.” Visitors easily identify the “prickly pear,” also called “Mickey Mouse ears” or “cactus rackets.”

(Photos used with permission.)

 

Will Frost Hurt Your Succulents?

Succulents from certain parts of the world, notably lower elevations of South Africa and Madagascar, are vulnerable to freezing temperatures. If the forecast is for temperatures below 32 degrees F, throw a sheet over your crassulas, kalanchoes, aeoniums, stem euphorbias and aloes before nightfall and remove it in the morning. See how I do it in my own garden in this video, Protecting Your Succulents from Frost.

Frost that nips your succulents may turn their leaves brown and unsightly. How do you know if a plant is worth keeping? It may depend on how patient you are. Even badly damaged succulents are surprisingly resilient, but it may take months before they look good again.

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Temperatures below 32 degrees caused the fluid in this aloe’s cells to expand and burst, irreparably damaging the tips of many of its leaves. Luckily for the plant, those same leaves protected its core, which is still green and viable.

Aloe pruned_resized

If you decide to try and salvage a succulent with this sort of damage, wait until the weather warms in spring, then snip off the dead tissue. Because new growth forms from the center of the rosettes, pretty soon the old leaves will be barely noticeable.

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And now you know that this is one succulent that needs covering next time there’s a frost advisory for your area. Here’s how my garden looks when temps are predicted to drop below 32 degrees F.

Notice that Agave attenuata tucked beneath the tree on the left? It’ll be fine because the tree will protect it. The plants you have to worry about are those that are out in the open, with nothing above them. I sometimes stand over a succulent and gaze upward. If there are no tree limbs or eaves directly overhead, it gets draped. (I use old sheets. Several years ago a nongardening friend, stopping by for a visit, asked if I was doing my laundry.)

How do you know if you live in a frost-free area? Your neighbors grow Agave attenuata in their gardens, and the plants look fine. In my garden, this soft-leaved agave is the canary in the mineshaft where cold is concerned.

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It’s the first plant to show damage from frost in winter. A lot of succulents can handle cold below 32 degrees for short periods. But Agave attenuata will look like this the next day. This is a nuisance, but fortunately not fatal.

Agave attenuata cropped

See the healthy green part of each leaf? Wait until spring, then use scissors to trim off the tissue-paper-like frozen tips, cutting each leaf to a point. When you’re done, the damage will be barely noticeable. By summer new growth will have hidden the short lower leaves.

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What about a succulent that has frost damage only on its leaf tips? Don’t bother to trim them. It’ll lose those oldest leaves in a few months, anyway.

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Kalanchoes tend to be quite frost-tender. One similar to this melted to the ground in my garden at 27 degrees, and I assumed it was a goner. Fortunately I didn’t dig up the damaged plant and discard it, because a few months later…

Recovered kalanchoe_annotated_resized

…it came back from the roots.

Jade plant is another widely cultivated succulent damaged at 32 degrees. The leaves turn squishy and putty-colored. This is not pretty, but if the plant’s stems are firm, it will recover and grow new leaves.

Jade, semiburned resized

Actually, the jade plant in the photo was not a victim of frost. You know the term “frost burn?” This plant actually was burned…by a wildfire. The only indication that it wasn’t “burned” by frost is that frost tends to damage the top of a plant. This one was scorched on the side closest to the fire. (Which just goes to show, succulents cook rather than burn, but that’s a different post.)

If you live in an area where you can’t grow most succulents in the ground because it gets too cold, take heart…there are varieties that will do well for you. I recommend this excellent book: Hardy Succulents by Gwen Kelaidis, photos by Saxon Holt.Screen shot 2016-01-05 at 7.59.00 PM

Go to my post: Four Ways to Overwinter Your Succulents

Learn more in my book, Designing with Succulents (2nd ed.):
— Cold-Climate Succulent Gardens, pp. 111-113
— Cultivating Succulents in Challenging Climates, pp. 143-148