Sempervivums – spectacular, hardy and monocarpic!

Sempervivums – spectacular, hardy and monocarpic!

Being a lover of the hardier kinds of succulent, Sempervivum are certainly up there in my top 10.  They are just as hardy as any Echeveria, Crassula or Agave succulent in my opinion.  They can survive heat, drought, frost and general neglect and still look fabulous.  In Europe their common name is House Leek, in the United States it is Hen & Chicks. Here are a few facts and pointers for the Sempervivum genus.

Succulent Family
A member of the Crassulacae family Sempervivum are native to the mountains of central and southern Europe and can grow at 3000-8000 feet above sea level. There are about 50 different species.  They vary in size, form and colour and grow in rosette formation. The name Sempervivum comes from the Latin words semper, meaning “always,” and vivus, meaning “living.”  Which describes its everlasting nature. Pronounced: Semper Vee Vum.

Characteristics
Sempervivums come in many colours such as pink, orange, yellow, red, green and brown.  To see its colour in full glory they need to grow in full sun. If not grown in full sun they will grow as green in colour.  Mature plants can be from half an inch to 6 inches (1 to 15 cm) in diameter.

Sempervivum Tectorum

Sun Lovers
Even though Sempervivums are native to Europe which is not well known for its hot summers.  Sempervivum cope, and dare I even say ‘love’, full sun. They do not need  a lot of water and are drought tolerant.  This is great news for hot Australian Summers, however I would be inclined to cover them if the temperature if forecast over 40C/104F as their leaves may get sun burnt.  I would suggest that this would not kill the plant but probably just look a bit unsightly until the sun burnt leaves shrivel and drop off.

Frost Tolerant
On the other side of the coin Sempervivum are one of the most frost resistant succulents.  This would be due to their origins being in mountainous regions of Europe. They can survive in extremely cold temperatures, most will survive temperatures as low as -30F/-34C apparently.

Light and Water Requirements
Sempervivum can survive in full sun and tolerate drought conditions.  They do not require a lot of water but can also survive a wet winter as long as they are growing in well drained soil or on a slope if grown in the garden.  If grown in pots move them under the eaves of the house to avoid temperature fluctuations and avoid wet winters.

Sempervivum monocarpic succulent

Hairy Semps
Some species of Sempervivum are…….. hairy. That is the only way to describe them. They have tiny white hairs growing along their leaves and also on the tip.  This is the best way to distinguish a Sempervivum from any other rosette forming succulent.  Only Sempervivum have these tiny hairs.

Hairs on Semperivum

Hairs on Sempervivum

Sempervivum covered with cobwebs
Sempervivum Arachnoidium looks like it is covered in spiders webs.  (see below).  It is another amazing succulent.  The cobweb starts off in the middle of the plant and eventually spreads to cover all leave in the rosette.  It can then spread to cover the clump of Sempervivums.

sempervivum arachnoidium succulent

Sempervivum Arachnoidium Pygmalion

Propagation
Most Sempervivum are prolific at producing offsets which grow off the side of the parent plant and produce a large clump. However, some Sempervivum produce offsets on the end of long stems which are called ‘stolons’ these then set down roots at a distance from the parent plant. Once the roots have developed the plant can be grown independently from the parent plant.

Sempervivum propagation

Sempervivum Tectorum with stolons

Flowering – and the bad news
Flowers are shades of pink, red and sometimes yellow. If and when Sempervivum flower it happens in mid to late Summer. The bad news with regard to Sempervivum flowers is that Sempervivum succulents are monocarpic which means that the parent plant dies after flowering. It will shrivel and die.  It can then be easily pulled out and this will allow room for the pups to spread. Sempervivums are perennials so they live for at least 3 years or more before they flower. Sempervivum flowers produce a star-shaped fruit containing seeds which can be collected and grown. See Post : Which succulents die after flowering?

Uses
In Europe Sempervivums were traditionally grown on roofs.  They were thought to ward off evils spirits and raging storms.  Below are a couple of examples from Pinterest.  I assume they would need to be grown on a pitched roof for water to run off so as the roots are not sitting in water.

Image result for sempervivum green roof Image result for sempervivum green roof

Problems
Being as hardy Sempervivum are they do not have many additional problems to deal with.  Any succulent is prone to mealy bugs or powdery mildew and root rot from over watering.

Which succulents die after flowering?

Which succulents die after flowering?

I was shocked and a bit devastated when I found out that some succulents die after flowering.  It’s not something you should blurt out to a novice succulent lover!  But do not worry, of the thousands of different succulents there are only a very small number that are ‘monocarpic’.

Monocarpic plants flower, set seed and then die. Other words with the same meaning are hapaxanth and semelparous.  However monocarpic is the term that is used to describe the succulent process.  Probably because it is easier to say!

Monocarpic plants can be divided into annuals, biennials and perennials. Annuals flower and set seed in one year, biennials two seasons and perennials sometimes take many years to flower.

So the question is: how long does a succulent live before it flowers??  The good new is:  Succulents that are monocarpic can still live a long life as they are perennials.  Below are the succulents that I am aware are monocarpic.

Agave – Attenuata/Americana (Century Plant)
The above monocarpic Agave’s can take 10 -25 years before the parent plant flowers.  When it is ready the plant uses all its energy to produce a thick stem which grows from the centre of the rosette in a relatively short period of time – sometimes less than a week. The stem can grow up to 2.5 metres (8 feet) high.  The Americana (Century Plant) has a stem that can grow to 9 metres (30 feet).  Once it flowers the parent plant will wither and die, Compared to other succulents the Agave parent plant can take months or even years to die.  Agave pups grow along the stem of the flower, these can be harvested and replanted.  Any pups that have grown off to the side of the plant will not die, only the rosette that has produced the flower stem.

Some, but not all, Agave are moncarpic.

Variegated Agave Succulent

Sempervivum
All succulents in the Sempervivum genus are monocarpic.  At first this made me think twice about buying Sempervivum succulents. Each rosette only flowers once and then dies. However, most species produce lots of offsets which makes up for any loss after flowering.  It will take 3 to 4 years for the rosette to produce a flower and die, in this time the parent plant would have produced many pups/babies to continue on in your garden.

monocarpic sempervivum

Sempervivum Tectorum

In Europe they are known as ‘houseleeks’ but in the USA Sempevervivum are known as Hen & Chicks.  However, some people call the Echeveria genus Hen & Chicks as well. Thus, it can get very confusing and people think that their Echeveria succulents are monocarpic.  It is ‘only’ Sempervivum Hen & Chicks which are monocarpic not Echeveria.

There are some Sempervivum and Echeveria that look very similar, they both have rosettes.  If you think your succulent is a Sempervivum and it flowers – from the centre of the rosette- and does not die – suffice to say this is an Echeveria.

The photos of the sempervivum below show small offsets from the sides.  These can be mistaken for flowers.  They are not flowers but new plants/pups sprouting.  When a Sempervivum flowers it is from the centre of its rosette, not to the side.

 

Aeonium
Some Aeonium will flower within two years while others may take 10-20 years before they flower. They die completely after flowering but before do they will have produced offsets as well as large numbers of seeds. Not all Aeonium die after flowering, but for the one’s that do it is too late for the plant once the flower stalk starts to develop.

Aeonium Aboreum Fire Wise Succulent

I found this Aeonium (below) in a nursery.  It looks very pretty, but as it was flowering I figured it wouldn’t have a very long life span in my garden if it was an Aeonium that was monocarpic!  Something to be aware of for monocarpic succulents.

Aeonium flowering

Kalanchoe 
The Kalanchoe ‘Flapjack’ is a monocarpic plant, once the Kalanchoe flowers new “baby plants” can be seen at the base of the plant and along the flower stalk. They can easily be propagated from the stalk.

IMG_5799Propagating Kalanchoes after bloomed!

So, if you have any of the monocarpic succulents you should be prepared for its dramatic flowering death at some point!