Succulent Hybridising and The Origin of x Semponiums
How and why Surreal Succulents bred x Semponiums
Since founding Surreal Succulents, Daniel Michael has created some beautiful Aeonium hybrids which are enjoyed globally, such as Aeonium 'Phoenix Flame', Aeonium 'Emerald Flame', Aeonium 'Blood', Aeonium 'Cornish Rose' and Aeonium 'Pomegranate'.
Already with many years of experience hybridising, Daniel had often talked to RHS botanists about the theoretical chances of crossing other members of the Crassulaceae family.
While some of these such as 'Pheonix Flame' are tested frost survivors, generally Aeoniums are tender plants which need protection over winter in the UK. So, we started looking into how we could create plants with the beautiful architectural structure of Aeoniums with some of the hardiness of other succulent species, such as Sempervivums.
What are x Semponiums?
x Semponium is an inter-generic hybrid consisting of Sempervivum and Aeonium. This was possible as they are genetically similar with both being members of the Crassulaceae family.
Sempervivums are generally small, compact plants which are extremely hardy and can withstand freezing temperatures as low as -20°c.
Aeoniums tend to be much larger and mostly frost tender, with only a few species and hybrids being able to take frosty conditions.
Sempervivum
'Green Ice'
X
Aeonium
'Ice Warrior'
=
x Semponium
'Sienna'
x Semponium
'Destiny'
x Semponium
'Diamond'
x Semponium
'Mrs Frosty'
x Semponium
'Halo'
x Semponium
'Vortex'
How was this possible?
Sempervivum 'Green Ice' flower
Two plants were used to create these amazing inter-generic hybrids, and that might sound simple at first. However, their flowering seasons couldn’t be more different. Aeoniums bloom in early spring, while Sempervivums flower in mid-summer. They almost never flower simultaneously. Bringing these two worlds together takes careful timing, expert knowledge, and a little bit of horticultural magic.
Aeonium 'Ice Warrior' flower
At the nursery, we had a late flowering Aeonium ‘Ice Warrior’ which was moved to a cool, shaded spot to slow down the flowering process in an attempt to preserve the plant for a once in a generational cross. Sempervivum ‘Green Ice’ was chosen being a strong Sempervivum cultivar.
The breeding process
In our breeding, we have found that using hybrid mothers, rather than two specie mothers, gives you a larger genetic pool with many more possible exciting outcomes.
Think of it like a family tree, these hybrid seedlings would have four or more differing original specie parents, rather than just two.
Breeding two hybrids increased the seedling genetic DNA and random trait potential, maximising our chances of the x Semponium to show up.
Ripe Sempervivum 'Green Ice' Seeds fertilised with Aeonium 'Ice Warrior' pollen
The cross was by no means easy to pull off. The chosen plants had to be carefully contained to stop any cross contamination from other pollinators. We used methods like covering the flowers with fleece bags, cutting all other Aeonium and Sempervivum flowers and moving them into quarantine to minimise any contamination risk.
With the goal being hardiness, it was decided that the seed bearing plant would be the Sempervivum. The theory was that this would maximise the hardiness that the Sempervivum could offer and that we could clearly identify that a hybrid seed was achieved.
The Aeonium ‘Ice Warrior’ had an abundance of good, strong, healthy pollen. This plant has an extremely long flowering period, sometimes up to ten weeks.
Sempervivum ‘Green Ice’ produces a short flower spike with up to twenty flowers, only lasting for three to four weeks.
5 day old x Semponiums
In the summer, Daniel took fresh pollen from the Aeonium ‘Ice Warrior’ and carefully transferred it to the newly flowering Sempervivum ‘Green Ice’ using a soft paint brush and tweezers.
He then left the flower to ripen in a dry sunny spot for eight weeks. After this period, he then collected the flower heads and left them to dry out completely in a brown paper bag in a cool, dry place for a further two weeks.
After the two weeks, we removed the fine dust like seed from the chaff of the flower, then carefully packaged into a cellophane envelope and clearly labelled it, which was then stored in the fridge for two more weeks until sowing.
The seed was then good to go.
Come late Autumn, a total fourteen weeks later, Daniel took the fine seed and evenly distributed it over the surface of a tray of sterilized seed compost. He then covered the seed with fine sand and carefully soaked the seed tray in a bath of sterilized water. A thin piece of glass was placed over the top of the seed tray, trapping in the humidity to aid germination. The tray was placed in a bright spot and left. We now patiently wait.
Daniel eagerly checked the seed weekly, hoping to see signs of germination.
By week three we could see signs that the seed had germinated, but there wasn't enough evidence at this point to know if the cross had been successful, more time and patience was needed.
A further two to three months later, to our excitement, we saw growing variation in the seedlings, some red, some tall and Aeonium-like, and at this point, we knew we had done it; we were witnessing the birth of the world’s first official x Semponiums.
Once the seedlings where at a suitable size, we potted every single one on, giving each one star treatment. This was important as we didn’t want to miss any potential prospects.
Over the course of the growing season, we could select potential forms of interest and colour to grow on; this was an incredibly difficult task as we had so many different amazing looking variations.
We ended up choosing six varieties. These all had unique distinctions whether it was form, colour or vigour; each one looked completely different to the next.
Growing x Semponiums
The speed of growth of the x Semponiums is fantastic. They grow incredibly quickly and with strong hybrid vigour. The leaves look fresh and clean all year round. They also seem to have a shorter dormancy stage than their Aeonium parents.
Hardiness was the key trait that we wanted to bring up in these new hybrids. We wanted a garden-proof Aeonium-like plant suitable for all regions in the UK. Unfortunately, the hardiness trait of the Sempervivum mother did not transfer to the x Semponiums, rendering them to the same tenderness as Aeonium 'Ice Warrior', which is know to only just survive -4°c. This was extremely disappointing to discover as this would have been one of the greatest hybridising achievements in history.
Daniel, and the rest of the Surreal Succulents team, is still attempting to breed hardiness into Aeonium, one hybrid at a time. Our goal is to curate a selection of plants that are winter hardy for everyone to enjoy without the worry of losing them.
RHS awards
The x Semponiums had received great interest from the community and we decided to show them for the first time at the RHS Chelsea Flower Show 2020. Unfortunately, this show was cancelled because of the pandemic. So, we decided to keep them from public eye until the show returned in September of 2021.
x Semponium 'Sienna' was featured in our Gold Medal winning 2021 show garden. We had entered‘Sienna’ into the 'Plant of the Year' competition. The plant was awarded third place in the RHS Chelsea Flower Show Plant of the Year for 2021.
The following Chelsea Flower Show in 2022, x Semponiums 'Diamond' and 'Destiny' were revealed to the public. We had also entered these two hybrids into the Plant of the Year competition, and to our surprise, 'Destiny' had won 1st place!
We could not believe it! It was truly a Surreal experience.
The future for x Semponiums
We are always trying new and exciting hybrids for x Semponiums, now we know how it is done.
The next release to our x Semponium range was x Semponium 'Darwin', officially released in April of 2025. This plant is a completely different cross to the original 6 plants, as those were Sempervivum 'Green Ice' x Aeonium 'Ice Warrior'. 'Darwin' is a cross of Sempervivum 'Pink Puff' x Aeonium nobile.
'Darwin' is a distinctly unique addition to our range, with its deep red colouration and huge chunky leaves, showing a combination of the two mother plants.
Unlike the first x Semponium series, this seed batch was less successful, as 'Darwin' was the only unique seedling. The other seedlings had no resemblance the the Aeonium mother plant.
We are looking forward to creating new x Semponiums in the future, and we press on with our mission of breeding extreme hardiness into the Aeonium gene pool.
Thank you for reading!
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