Plant hybridization
Winter Hardy Agave Hybridization
Growing agave in a high-rainfall, cold winter climate has its challenges. We have been growing hardy agaves in our wet, Zone 7b garden since the early 1980s. In that time, we’ve grown quite a few agaves in the ground (2180 taxa), killed quite a few agaves (1528 taxa). In doing so, we’ve learned several lessons. First, each clone varies with their ability to tolerate cold wet conditions in the winter. Second, the species genetics matter.
We determined that there were 23 species, which had any chance of winter hardiness here, assuming we found the right clone.
asperrima (since 2003)
bracteosa (since 1999)
difformis (since 2010)
gentryi (since 1999)
flexispina (since 2010)
funkiana (since 2006)
havardiana (since 2006)
lechuguilla (since 2006)
lophantha (since 1994)
montana (since 2015)
multifilifera (since 2010)
nickelsiae (since 2016)
ocahui (since 2010)
ovatifolia (since 2006)
palmeri (since 2001)
parryi ssp. couesii (2012)
parryi ssp. huachucensis (2005)
parryi ssp. neomexicana (2015)
parryi ssp. parryi (2016)
parryi ssp. truncata (2010)
parviflora ssp. flexiflora (2010)
pintilla (2016)
polianthiflora (2011)
potrerana (2010)
schottii (2006)
striata (1999)
victoriae-reginae
There are also a few agave species which are plenty winter hardy here, but dislike our wet weather, which averages around 45 inches annually. These include:
chrysantha
mckelveyana
utahensis
In addition to selecting clones of the winter hardy species, we next tried growing hybrids with these species and were subsequently able to add an additional 16 taxa. From there, the only way to acquire more was to create more ourselves via a breeding program.
Other hybrids agaves (16) which are hardy here
x brachantha – bracteosa x lophantha (2010)
x gentana – gentryi x montana (2000)
x gentrifolia – gentryi x ovatifolia (2006)
x glomeruliflora – havardiana x lechuguilla (2006)
x gracilipes – parryi ssp. neomexicana x lechuguilla (2014)
x havardasana – parrasana x havardiana (2013)
x lechuphantha – lophantha x lechuguilla (2004)
x lechusperrima – lechuguilla x asperrima (2016)
x mitiflora -mitis x polianthiflora (2014)
x nickelima – asperrima x nickelsiae (2004)
x nickuilla – nickelsiae x lechuguilla (1999)
x ocalifera – filifera x ocahui (2016)
x parrmeri – parryi x palmeri (2013)
x protamericana – americana x asperrima (1999)
x pseudoferox – americana x asperrima x gentryi (1999)
x striateosa – striata x bracteosa (2006)
x victosa – bracteosa x victoriae-reginae (2004)
The beginning
Our agave breeding program began in earnest in 2009 with our successful cross of Agave lophantha (female) x Agave salmiana var. ferox (Hort.), We refer to the pollen donor as Agave x pseudoferox, since true Agave salmiana var. ferox isn’t remotely winter hardy in our climate. The pollen came from the winter hardy clone Agave ‘Logan Calhoun’. We named this hybrid group Agave x loferox ‘Stairway to Heaven’. Most of the F1 plants matured in the range of 3’ tall x 7’ wide, with most producing many tightly held offsets. A few of the seedlings showed a faint central stripe of the Agave lophantha parent, but none were good enough to become clonal selections for that trait.
From this initial cross, we planted 11 clones in the ground for evaluation and hardiness trials, of which 7 remain. Four clones, Agave ‘Hacksaw’, Agave ‘Family Affair’, Agave ‘Swords a Plenty’, and Agave ‘Sunbeam’ were selected and named from those initial plantings.
These Agave x loferox hybrids went in the ground in spring 2011, so we were quite surprised to find them coming into flower in spring 2016. These hybrids are unquestionably the most precocious flowering century plants that we grow. The flowers of Agave x loferox were remarkably uniform, appearing completely intermediate between the spicate and paniculate groups of flowering century plants. Spike height ranged from 12’ to 15’ tall.
2010
In 2010, we made a similar cross using Agave lophantha as the pod parent and a different clone, Agave x pseudoferox ‘Green Goblet’ as the pollen parent. This strain was named Agave x loferox ‘Heaven Sent’. The resulting seedlings were fairly similar to our original 2009 cross, so we on kept two clonal selections to plant in the garden, of which one still survives.
2012
In 2012, we were able to use Agave victoriae-reginae as a pod parent for the pollen of Agave x protamericana ‘Blue Steel’. We assigned the nothospecific name Agave x protareginae to the hybrid offspring. Of the twelve clones that went into ground trials in 2016, we have two which remain alive. These were anything but intermediate with regards to size as both took on the size of the Agave victoriae-reginae parent, but with the leaf coloration from Agave x protamericana.
2013
In 2013, we crossed a wide-leaf, heavily banded selection of Agave lophantha , A. ‘Band Aid’ with Agave striata, using Agave striata as the pod parent. We named these offspring Agave x striphantha ‘Band on the Run’. All seedlings showed some semblance of a central stripe from the Agave lophantha parent, but some were more intense than others. Of the eight plants we selected for planting in the ground, five remain alive in 2022, and one particularly good selection was christened Agave x striphantha ‘Striptease’. It has matured into a 2’ tall x 3.5’ wide specimen with Agave striata-like foliage, but with a central chartreuse foliar stripe.
2014
In 2014, we crossed Agave flexispina in the garden with the pollen from the large Agave x pseudoferox ‘Bellville’. We named these offspring Agave x flexiferox. Because of the paucity of seedlings, we chose not to give this a seed cultivar name. Beginning in 2016, we planted 8 selected clones in the garden. Two clones have been selected and named so far, both for exceptionally large and showy teeth, Agave ‘Megalodon’ and Agave ‘Velociraptor’. The size of these hybrids seem like they will be intermediate between both parents, and we anticipate a mature size of 4’ tall x 6’ wide. All clones seem to offset sparsely.
In 2014, we also crossed Agave ocahui x victoriae-reginae using the pollen from Agave victoriae-reginae. We named the seed strain, Agave x ocareginae ‘Oh Victory’. When the seed-grown plants they were large enough, we selected 9 unique clones, which were planted in ground trials. Of those, five remain alive in 2022. The size of the hybrids is so far is comparable to both parents.
In 2014, we also crossed Agave x protamericana JLBG-07 and Agave x pseudoferox ‘Bellville’. Our goal was to use our two largest hardy clones to see how large a plant we could make from combining the genes. The cross was made both with Agave x protamericana as a pod and pollen parent. The resulting seed strain from using Agave x protamericana as a pod parent was named pseudoferox ‘Bluebell Giants’ and the reciprocal cross, was named Agave x pseudoferox ‘Big Bluebell’.  Eleven plants of Agave ‘Bluebell Giants’ were planted in 2016, but only two survived our 2017 winter. Of the eleven plants planted from the reciprocal cross, Agave ‘Big Bluebell’, none survived. We have named one huge, blue-foliage clone that survived our brutal 2017 winter as Agave ‘Supersize’.
Nomenclaturally, we feel that Agave x protamericana and Agave x pseudoferox is a mess. We feel like more than one species is entangled in both entities, and in fact they may wind up being variants of the same mix.
In 2014, we also successfully put the Agave x victoriae-reginae pollen onto Agave x pseudoferox ‘Bellville’. This resulted in plants, we named Agave x victoferox. Because of the small numbers, we didn’t assign them a seed strain name. In 2016, we planted out six clones, of which four remain alive in 2022. These have proven to be exceptional plants with great form and a imtermediate size between both parents. The foliage markings are quite reminiscent of Agave montana. We have named three clones from this cross, Agave ‘Architexture’, Agave ‘Upstanding’, and Agave ‘Nestuary’.
Finally, in 2014, our volunteer agave curator, Mike Papay made crosses using the pollen from our Agave flexispina and his Agave schidigera ‘Durango Delight’. We named this seed strain, Agave x flexidigera ‘Durango Fandango’. We planted 8 of these in the ground in 2017, but a severe winter of 10 consecutive days where temperature never hit the freezing mark, wiped out all but one.
Mike was also successful when he applied pollen from Agave ‘Spine Tingler’ onto his flowering Agave schidigera ‘Durango Delight’. Agave ‘Spine Tingler’ is a plant which we believe to be a cross of Agave lophantha x lechuguilla, that we got from Ruth Bancroft, who got it from someone named Bob W. We consider this plant to be an Agave x lechuphantha.
We named Mike’s hybrids Agave x schuphantha (schidigera x lophantha x lechuguilla). Because there were only three seedlings to be planted out in 2017, we did not bother with a seed strain name. One of the offspring, which we view as exceptional, has been named Agave ‘Wheel of Fortune’. This elegant clone forms stunningly symmetrical rosettes, with leaf backs displaying the classic Agave lechuguilla leaf markings. Although Agave ‘Wheel of Fortune’ rarely offsets, when it does so, the new rosette pops up at least 3’ away from the parent.
2016
In 2016, we made three different crosses between our Agave x loferox and Agave ovatifolia. Mike Papay made two of those, using two different clones of Agave ovatifolia as the pod parent, and our Agave x loferox ‘Hacksaw’ clone as the pollen parent. We also made the reciprocal cross here using Agave x loferox as the pod parent. We assigned the strain name Agave x amourifolia to all crosses and gave unique strain names to each cross. Agave ‘Tongue Lashing’ was from A. ovatifolia ‘Blue Dreams’ x loferox ‘Hacksaw’, while Agave ‘Twisted Tongue’ was Agave x loferox JLBG-14 x A. ovatifolia, and Agave ‘Speak Easy’ was Agave ovatifolia MP01 x Agave x loferox ‘Hacksaw’.
We planted only 1 clone of Agave ‘Speak Easy’, and that was a fairly recent planting. We planted two clones of Agave x amourifolia ‘Tongue Lashing’ and both died…possibly a statistical anomaly. We planted 20 clones of Agave ‘Twisted Tongue (the reciprocal cross), however, and 18 survived. It should be noted that our winter temperatures have not dropped below 20 degrees F since these have been planted, although based on their parentage, single digits F should not be a problem.
With three species involved in the Agave x amourifolia cross, it isn’t surprising at the wide phenotypic variability we’ve seen. Some plants are small and barely offset, while others are running machines. Some have great leaf patterns, while others show exceptional teething. Foliage color ranges from green to glaucous blue. We have yet to select any named clones from this cross.
In 2016, we crossed our Agave x loferox ‘Hacksaw’ with Agave x protamericana ‘Grey Gator’. Agave ‘Grey Gator’ is the largest growing hardy agave that has survived to flowering in our climate. The resulting offspring, we named Agave x lophantha ‘Gatorade’. This was done with the same assumption mentioned earlier, that we believe Agave x protamericana and Agave x pseudoferox have the same genetics, despite their phenotypic differences. Seven clones were planted, but these are not mature enough for evaluations.
Also in 2016, Mike Papay made a cross of on his Agave ovatifolia, using pollen from our Agave x lechuphantha ‘Spine Tingler’. We were able to select four seedlings for ground trials, starting in 2016. Of those, only one remains alive. Phenotypically, the offspring resembles one of the pollen parents, Agave lophantha.
In 2016, Mike also put frozen pollen from our Agave flexispina onto his flowering Agave ovatifolia, resulting in a seed strain that we named Agave x ovatispina ‘Blue Rapture’. Fifteen clones were selected for the garden in 2018, and thirteen remain alive in 2022. These have shown to be exceptionally vigorous, and may get close to the size of Agave ovatifolia when mature. We have made one selection so far, which we named Agave x ovatispina ‘Blue Arrows’.
Also, in 2016, Mike crossed Agave x protamericana ‘Saltillo’ with Agave ovatifolia, which was the pod parent. We have given these the name Agave x protifolia ‘Emerald Giants’. Eleven clones were selected for planting and went into the ground in 2018. These are beautifully teethed plants with foliage color ranging from green to glaucous blue. It’s too early to know for sure, but these should prove to be massive plants with good winter hardiness.
Finally, in 2016, we were successful at crossing Agave ovatifolia on to Agave victoriae-reginae as the pod parent. We named our strain Agave x victorifolia ‘Queen’s Whalecome’. Seed was very sparse, but two plants were planted in the garden for evaluation in 2018.
2017
In 2017, we crossed Agave ‘Aristocrat’ (mitis x polianthiflora) and Agave ovatifolia as the pod parent. We only had a few offspring, which we christened Agave x elegantissima. Of the 4 clones that were in ground trials, 3 remain. It appears that the size will be intermediate between both parents.
Also, in 2017, we created hybrids of Agave ovatifolia and Agave x pseudoferox ‘Bellville’. Each plant was used as a pod and pollen parent. We used the nothospecific name Agave x ovox, with plants having Agave ovatifolia as the pollen donor becoming Agave x ovox ‘Big Ox’, and those with Agave ovatifolia as the pod parent becoming Agave x ovox ‘Large Ox’. The first selections went into ground trials in 2019, so it’s too early to draw any conclusions yet, but it’s the foliage ranges from shiny green to glaucous blue, and some of the forms we are seeing are rather spectacular. As you can imagine, this should be a massive sized plant.
2021
In 2021, we were able to make hybrids between Agave funkiana and Agave asperrima. It’s still too soon to draw any conclusion on the garden value or size of the hybrids.
Our breeding work continues, as does the process of final selection and propagation.