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ENCEPHALARTOS HORRIDUS

A STUNNING BLUE CYCAD
by Phil Bergman

Description of Article

Article about the stunning blue South African cycad, Encephalartos horridus.  This cycad doesn't get too large,
is a great silver-blue color and adds distinction to almost any garden.

Introduction

On the Internet there is very little well written and easy to understand information on the blue cycads of Africa.  This species is one of the more sought after and popular of all the blue cycads.  I hope this article will introduce the reader to this remarkable plant.  I've tried to include lots of photographs of the species and easy to read information on culture and usage in the landscape.

When one researches the derivation of the word "horridus", such terms as "bristle", "shutter", "shrink from" are found.  I think this all translates into the extremely prickly nature of the leaves and leaflets of this species.  Leaves emerge from the trunk, go upright and then, to a greater or lesser extent, curve downwards toward the ground.   Their length on mature specimens is usually two to three feet.  Dwarf forms can have shorter leaves.  The numbers of leaves vary with growing conditions but can be upwards of 20 or more.  Leaf width is about 6 inches.  As new leaves emerge, older leaves "lay down" closer to the ground.  There is a short bare petiole proximal to the inner leaflets.

The leaflets contained in the middle of a mature leaf on most forms are approximately three to five inches long and one to one and a half inches wide.  The most prominent characteristics are the barbs or lobes.  These are one to one and a half inches long.  There are two to three of these lobes present.  What distinguishes this species from similar species is that that one or more of these barbs are oriented in a different plant than the rest of the leaflets.  They flip back in orientation.  Also, they also can overlap.  This accentuates the prickly nature to the leaf.  The barbs also have a very sharp spine at the terminal point.  This "flip" of the lobes is much less apparent or nonexistent in the similar species E. trispinosus.  Proximal leaflets are reduced in size compared to leaflets farther out on the leaf in the mid-leaf area.  Below are photos of leaves and leaflets to give you an idea of their appearance.  As you look at them, look for the change in the orientation of the pointed lobes.

Encephalartos horridus (along with E. trispinosus, lehmannii and princeps) is described as a "blue" cycad.  In fact, this term "blue" is often used to describe many species of plants including popular palms like Bismarckia nobilis and Brahea armata.   But, I must clarify here that we are not talking about a dark blue like one would see in the ocean.  Rather, it is a "silver-blue".  I like to think of it as looking up at the blue sky above on a minimally foggy day.  So, if you were to refer to the color of this species as 'silver", you would not be wrong. You will see variations of this among representatives of this species varying from a definite blue green to a darker blue to a light silver and sometimes almost to a silver white color. 

This color is present because of a waxy substance that the leaflets produce on the leaflet surface.  It is almost like a fine powder.  It is most apparent on newer leaves and persists on the leaves over time.  But, with time and the physical action of rain and weather, can actually wash off of older leaves.  Or, it can become less intense and muted.  The wax is actually washing away.  It also wipes off with the stroke of your finger.  Another interesting thing about this waxy substance is that a plant grown in a very humid greenhouse may emerge quite blue, but over time convert to almost a green color.  This is very common to see.  But, when you move this green plant into the bright sun, this green color will gradually become more blue, especially on the newer leaves grown outdoors.  The same can be seen with a plant grown in the shade; it may be less blue. 

Also, a plant grown in a far interior area with very hot and intense sun will produce more protective wax and therefore be more intensely blue.  If you buy a plant out of a greenhouse that is not quite as blue as you like, the chances are that it will develop better color after planting in the sun in your garden.  Remember, the plant produces the wax as a form of protection from desiccation.  In a hot humid greenhouse, desiccation is less of a risk and the plant produces less or loses more of the wax.  Below are photos to demonstrate color of this species. 

OFFSETS OR SUCKERS OF ENCEPHALARTOS HORRIDUS

Like many other types of cycads, Encephalartos horridus can grow pups or offsets at the base of the primary trunk.  This is a form of natural propagation by the species.  Remember, the plant reproduces by the formation of seeds.  Offsets or pups are a form of propagation of the species but a vegetative type not requiring a nearby plant of the opposite sex.  With offsets, the sex of the offspring is always the same sex as the parent plant.  In other words, if you have a female, a removed offset will also be a female.  For those wanting to establish a reproductive colony of a species, getting a rooted out offset is a way to speed up the establishment of a breeding colony.  If you need a female, you can get one by getting an offset of a parent female.  Offsets begin as a small adventitious bud growing off of the base of the mother trunk.  These are often subterranean and might not initially be seen.  They are supported nutritionally by the mother plant until they are removed from the main trunk.  However, over time, they do produce their own roots and can be physically removed and grown as a separate plant.  Within a year or two, such suckers will form their own leaves.  When such suckers are removed, there is a technique for establishing them and giving them the best chance to survive.  Below I will discuss how to do this. 

A parent plant has the ability to produce a large number of offsets or suckers.  It is peculiar that some parent plants have a propensity for produces offsets.  And, others may never produce even one.  Also, some species are more inclined than others to make offsets.  E. horridus is known for producing good offsets.   When basal offsets are removed from the parent plant, typically within a few years that same plant will produce more suckers.  And, these likewise can be removed.  Below are some pictures of plants with pups at the base.   I will show a few close up pictures to demonstrate the suckers.  Note how the suckers are making their own leaves.  The third picture shows how you see leaves adjacent to the parent plant, but you cannot actually see the stem of the pup.  It is subterranean in this case. 

Like many other types of cycads, Encephalartos horridus can grow pups or offsets at the base of the primary trunk.  This is a form of natural propagation by the species.  Remember, the plant reproduces by the formation of seeds.  Offsets or pups are a form of propagation of the species but a vegetative type not requiring a nearby plant of the opposite sex.  With offsets, the sex of the offspring is always the same sex as the parent plant.  In other words, if you have a female, a removed offset will also be a female.  For those wanting to establish a reproductive colony of a species, getting a rooted out offset is a way to speed up the establishment of a breeding colony.  If you need a female, you can get one by getting an offset of a parent female.  Offsets begin as a small adventitious bud growing off of the base of the mother trunk.  These are often subterranean and might not initially be seen.  They are supported nutritionally by the mother plant until they are removed from the main trunk.  However, over time, they do produce their own roots and can be physically removed and grown as a separate plant.  Within a year or two, such suckers will form their own leaves.  When such suckers are removed, there is a technique for establishing them and giving them the best chance to survive.  Below I will discuss how to do this. 

A parent plant has the ability to produce a large number of offsets or suckers.  It is peculiar that some parent plants have a propensity for produces offsets.  And, others may never produce even one.  Also, some species are more inclined than others to make offsets.  E. horridus is known for producing good offsets.   When basal offsets are removed from the parent plant, typically within a few years that same plant will produce more suckers.  And, these likewise can be removed.  Below are some pictures of plants with pups at the base.   I will show a few close up pictures to demonstrate the suckers.  Note how the suckers are making their own leaves.  The third picture shows how you see leaves adjacent to the parent plant, but you cannot actually see the stem of the pup.  It is subterranean in this case. 

CULTURE AND GROWTH OF ENCEPHALARTOS HORRIDUS 

Soil:  Like many other types of cycads, E. horridus like a good draining soil.  What this means is that the water given to the plant needs to pass through the growing medium fairly quickly.  If you are making your own potting mix, this can be accomplished by adding coarse sand, pumice, scoria, good caliper decomposed granite, very fine rocks, or other coarse material.  Things such as fine leaf mold, very fine sand, clay-like topsoil or decomposed organic materials tend to slow the passage of water and retain moisture.  With a good mix, when you water a containerized plant, you should see water trickling out the bottom of the pot in a matter of seconds.  We give a good formulae for cycad soil elsewhere at this website.  Of note, we also use horticultural charcoal routinely in our cycad mix.  Shown below are a picture of pumice, coarse #12 grit sand, and a photo one of our cycad soils.  Over the years I have experimented with a variety of soils for cycads.  I have found that many different types of soil or mixes will work fine as long as they have good drainage.  In other words, no single mix "is the best".    

In terms of the best soil type in the garden, the same principals apply.  E. horridus likes good drainage.  You can actually dig a hole in the garden and fill it with water.  You'd prefer that this water disappears in a matter of an hour or two.  If it persists for more than 24 hours, you're going to have problems growing this species unless you change things.  Adequate creation of a good draining garden is beyond the subject at hand, but sometimes adding the additives above will help if you have drainage problems.  Also consider raised growing beds or "mounding" up the soil to produce a small hill and planting your cycad on top of this hill.  Growers in such rainy climates as seen in Florida or Hawaii often do this.  This allows the plant to spread out roots above the wet lower water table area. 

Sun:  In general, Encephalartos horridus, in general, prefer full bright sun and heat.  This is especially true along the coast where full sun is almost mandatory.  However, in far inland areas or desert climates, it may be necessary to give this species less than full sun.  In desert areas like Phoenix, Arizona or Las Vegas, Nevada a few hours of sun may be as much as this species can tolerate.  Knowing that your plant wants sun, you must remember to acclimate a purchased plant to your sun.  Plants grown under shade cloth or in a greenhouse are not used to outdoor sun.  In the greenhouse, their color may be green more than blue and they are seeing more humidity than they'll experience outdoors.  But, they will convert to blue in the sun.  One should slowly acclimate a greenhouse grown plant into the sun over time.  If you a growing this species as a houseplant, it would be advisable to put the plant directly in front of a bright sunny window.  If grown inside a greenhouse, put the plant in a hot and bright area of the greenhouse.  If you are trying to grow this species in a tropical area where you have long monsoonal seasons, consider putting the plant under a overhand or eave of the house where sun hits the plant but the rain doesn't reach it.  Or, if an open rainy area, make sure you're giving the plant good drainage.

Water:  This species of cycad doesn't need or want a lot of water.  One could almost consider it xerophytic because it can go a week or two between waterings.  Too much water and continual damp soil are an enemy of not only this species but also of many cycads.  In most gardens in warm climates, watering plants twice a week is adequate.  During the winter you may not have to water the garden for a month if you get adequate rain.  At our nursery, we water containerized cycads ever week to ten days.  During hotter summer periods we may water twice a week.  It is probably better to give less frequent deep watering as opposed to frequent shallow watering.   You can evaluate your watering by checking the top inch or two of the medium.  You should allow this superficial soil to dry out before giving more water.  I like to tell clients at the nursery that under-watering rarely gets these plants in trouble.  Over-watering can kill them quickly. 

Fertilizer:  Similar to palms, cycads like an N:P:K ratio of approximately 3:1:3 or 3:1:2.  This would translate into an actual fertilizer with a ratio of 15:5:15 or 12:4:8.  For the garden, we prefer slow release preparations that are time-released over a given period.  Most slow release fertilizers are either 90, 180 or even 360 day formulas.  Follow the directions.  Also, get a fertilizer that has microelements such as magnesium, iron, etc.  When applying fertilizer, spread it onto the surface of the soil below all the leaves.  Do not throw it directly into the crown of the plant and try to stay about six inches away from the stem.  You can rake the fertilizer into the soil if you wish.  Below are pictures of fertilizer preparations.  the second photo shows a soluble fertilizer like we use inside our greenhouses.  I show it so you can see a list of container microelements.

Pests:  
In California, our two main pests are mealy bugs and scale.  In other areas of the country, different pests may be more of a problem.  As of yet in our locality, we do not have problems with Asian Scale as one sees in Florida and the Southeastern U.S. states.  Fungal problems do occur and are usually the result of poor culture, especially overwatering and poorly draining soils.  Mealy bugs are especially prevalent in greenhouse culture and can be controlled by utilizing horticultural oil, sometimes in combination with Malathion.  Good air ventilation and keeping the humidity low in the greenhouse helps with culture and prevention of insects.

GERMINATING SEEDS AND GROWING YOUNG PLANTS OF ENCEPHALARTOS HORRIDUS

Remember that setting seeds on E. horridus requires both a male and female cone with either natural or assisted transfer of the pollen to a receptive female.  Pollinated seeds remain with the cone until they are mature.  At that point they will easily pull out of the cone.  It is best to remove this fruit but use protective gloves when you do this.  Usually this is done manually with a pocket knife.  Whether you buy seeds or collect them yourself, they need a period of rest before you put them down to germinate the seeds.  This resting period can be three to six months.   Store seeds in a well ventilated container (such as a woman's nylon stocking) and keep them in the dark.  Once a month or so you might consider spraying them with water mist.  This is to help prevent desiccation from dry air.  They need this "after-ripening" period (period to mature after the seeds become "ripe" in the cone) to mature for germination.  After this period, soak seeds in clean water for 24 hours prior to potting them up.  We germinate them in a seedling mixture that is one part coarse peat moss and two parts Perlite #2.  We lay the seeds on their sides, about half under the top of the mix and half above the surface.   If available, bottom heat will assist and speed up germination.  We usually germinate many seeds together in one container, but you could do one seed per small pot if you wish.  We recommend misting the seeds or watering them about ever two, possibly three days.  Germination typically takes three to six months.   For domestic seeds, if you get 50% of the seeds to germinate, you're doing a good job.  25% success is more typical,. 

Once you have a hardened off single leaf, you can repot it into a container. If you let them stay on bottom heat too long, the enlarging main radicle root can grow down to the heating pad and burn, causing rot.  When repotting, give your seedlings a deeper pot if available.  Remember to use a cycad soil, not the germination mix above.  Shown below is a picture of a new Encephalartos horridus seedling.  It takes about four years to produce the 5g plant shown below.   The 15g below took a few more years from the 5g.  Note how this plant is "clustering" with several offsets at this age.

USAGE OF ENCEPHALARTOS HORRIDUS IN THE LANDSCAPE

Encephalartos horridus is a great addition to almost any garden where weather permits it to thrive.  When selecting a location to grow one, do not put it too close to a pathway as the leaves are very prickly.  But, don't put it so far back in the garden that you cannot see it.  As this is a relatively small cycad, it should be no more than six to eight feet from a vantage point to properly see and enjoy the plant.  If it's placed behind other plants or behind larger cycad species, it would not be visible.  Also plant it in an area of full sun if you are along the coast.  Guarantee that you've selected a location where adjacent plants won't, over time, shade out your horridus.  Some like to plant E. horridus in colonies for future seed production.  Others like to have a "blue area" of the garden and put horridus with similar blue species like lehmannii and trispinosus.   However you plan to do it, you'll really enjoy having this blue cycad in the garden.

Encephalartos horridus is a very rare and desirable blue cycad that does well in Southern California and many areas around the world.  It is small to medium in size and never gets over about six feet tall.  It is a very prickly plant with pronounced barbs on the sides of its leaflets.  It has blue leaves which are the result of a protective wax produced by the leaves.  In hot desert areas it is best to give it some protection from full sun.  This species likes soil with good drainage and doesn't like to be over-watered.  It is easy to grow if given the correct growing conditions.  Like all cycads, this species produces reproductive cones.  There are both male and female plants and pollen must be transferred to the female cone to make fertile seeds.  The species is propagated by seeds from the cones or from vegetative means by rooting out naturally occurring offsets from the base of a parent plant.  When grown in the garden, proper selection of location is important so people walking by don't brush up against the prickly leaves and so the plant always gets adequate sun.  Among enthusiasts, this is one of the most sought out of all cycads and is always hard to find and usually expensive to buy.    

Thank you for reading this article.  Feedback always appreciated.  Check elsewhere at this site for over 4000 photographs and  50 articles on palms and cycads.

Phil Bergman

Owner

Jungle Music Palms and Cycads

Nursery: 450 Ocean View Ave, Encinitas, CA 92924

Phone: 619 291 4605

Email: phil.bergman@junglemusic.net

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