Erodiums

10 comments

BY JOHN BEAULIEU (pronounced BOWL-you)

I don’t think Erodiums are as popular as they should be, but being a Hardy Geranium enthusiast in this part of Canada has it’s own challenges, and I should not be surprised that these lesser known cousins are not very well known. Of course, the main challenge here is that there is so little known and published about the hardiness of these plants. The next challenge that I have come up against, is getting a proper identification for those erodiums that I do get hold of. Erodiums are extremely popular in the United Kingdom and parts of Europe, but there is a big difference between the winter temperatures in England and those in central Ontario.

You can see that even though Ontario is further south than England, there is a big difference in the hardiness zones. Using the popular USDA zones, here in central Ontario we are zone 4, while much of England is in zone 8. In North America, England compares to the southern United States, and in Europe, we would compare to Moscow! We will often reach -35° C in the depths of winter, while a friend up in Northumberland, England, tells me that a cold night would be only -8° C. We are however, very lucky to have good consistent snow cover for most of the winter months (December through to early April) and that helps us grow varieties that a wet English winter (without some protection) would kill.

I start to worry when we do not get that good snow cover as soon as we should. The foliage of the erodiums can look quite attractive covered with frost, but I’m afraid that a lot of this exposure would eventually do them in. Here in central Ontario, we would usually have some snow cover from mid-December on… But on that rare occasion we will have a ‘green Christmas’.

It can be even more nerve racking at the end of winter, if we lose the snow cover early, and then get a return of the deep freeze (-25°C or colder). More plants are lost at this time than any other.

There are quite a few erodiums that can’t take any freezing temperatures at all, and this is where the lack of information regarding those plants and the Canadian climate is really hindering the popularity of erodiums… People become discouraged when they lose plants because they did not get proper information on the hardiness.

One of the most likely Erodiums that a Canadian will come across is Erodium x variabile ‘William Bishop’. This Erodium is often seen at garden centres, and now with the popularity of ‘Fairy Gardens’, tiny plants of ‘William Bishop’ are showing up among the pots of fairy garden plants. Usually the correct name is not given, and there is no mention that it is not winter hardy here! The disappointment of the plant not surviving outdoors over the winter can discourage people from trying other Erodiums.

‘William Bishop’ can be grown outdoors, and it is best in a rock garden situation… However, it MUST come indoors for the winter. I have found that they will flower right through the winter if they are placed in a good location under lights, such as you would do with African-violets or other Gesneriads.

This variety of Erodium has been known for many years as ’Bishop’s Form’, but in the world of plant taxonomy the use of ‘Form’ is not acceptable. A little research was done to find the full name of the person that was referred to, and the new accepted name for this plant is ‘William Bishop’. These are not wild species plants, but rather a complex hybrid involving Erodium corsicum and Erodium reichardii, and a lot of selection and possibly other hybridizing over many years. The plants originating from those two species crossing are known as Erodium x variabile. An older name for E. reichardii was E. chamaedryoides, and many decades later, we still see this name being used for selections of Erodium x variabile!

The Erodium x variabile group can be very variable! They can be lacking the pink petals of ‘William Bishop’, but still have deep pink veining right through to almost pure white.

There is also a double flowered form of E. x variabile, known as ‘Flore Pleno’. I was able to find this little treasure at a little independent nursery not that far away, Mason House Gardens. They have stocked a good variety of geraniums and pelargoniums for many years.

This group of Erodiums are easy to propagate, even though they do not set seed easily. They will produce sprawling side shoots that can be cut off and rooted as you would for typical tip cuttings.

I have gone as far as to take cuttings and root them in the holes of a brick for an interesting container. Any good potting soil will do, keeping it fairly moist until your cutting is well rooted. Planting is well draining situations is recommended for mature plants, whether in-ground or in a container.

One time, I had luck pollinating a ‘William Bishop’… It was indoors when they were over-wintering, and I used pollen from another non-hardy (in Canada) erodium, Erodium trifolium. Only one single seed was produced on that beak, but it did germinate and gave me a very interesting hybrid.

I called this hybrid ‘North Star’ because of the interesting shape of the flowers. The star shape is actually created because the edge of the petals roll in. The growth habit and size of plant is much closer to that of the E. trifolium parent.

Erodium trifolium is another erodium that I have to bring in for the winter, as it would never survive a Canadian winter. I have read reports that it is somewhat hardy over in the UK. My plant usually flowers indoors over the winter (under lights) and not always during the summer outdoors. By not flowering outside, it does not get pollinated and I don’t get any seeds for backup. This year (2017), I got flowers during the summer, and was able to collect a few beaks to give me some seed for backup.

A close up of one of the flowers produced outdoors in 2017.

This plant has a confusing name problem too… It is very often distributed in the various club seed distributions as Erodium pelargoniflorum instead of the correct E. trifolium. Many treat the names as synonyms, but they are not… The real pelargoniflorum is an entirely different species.

I did eventually discover a couple winter hardy erodiums, the first one being Erodium manescavii, which for this novice erodium enthusiast was quite exciting. I knew that this species was not all that popular with seasoned erodium growers in the UK, because it can seed around, and it also can cross pollinate with a few more desirable varieties. However, here in Ontario ‘beggars can’t be choosers’. I have never found it spreads all that much over here, again, probably due to very different growing conditions.

Seed of E. manescavii is often available from the club seed exchanges. I tend to order seed each year, and sow it to provide backup, as I’m finding there are occasional winter losses with this one.

The second hardy erodium that I was able to find at some select garden centres was known in the trade as Erodium chrysanthum.

While it is a hybrid of E. chrysanthum, it is not actually the true species. The real E. chrysanthum has much yellower flowers. It has been suggested that this pale version in the commercial trade (which are also all ‘male plants’) be called ‘Moonman’. Erodium chrysanthum and its hybrids are dioecous, meaning that there are separate male and female plants.

‘Moonman’ has proved to be a very hardy species, and I have had no losses through several brutal winter. Sadly, because they are all males, no seed is produced. The almost white flowers are quite attractive and the foliage has a bit of a silver look to it in the right light.

A few years back we visited Wrightman Alpines down near London, Ontario, just before they moved out to New Brunswick. I was amazed to see many varieties of erodiums growing and over-wintering in their rockeries. London is 2 zones warmer than we are, so I was not sure I they would survive here. I came home with four new varieties to give them a try.

The four varieties were; E. carvifolium, a species with really fine cut foliage, E. acaule (I’m not sure about this ID, as it had more markings on the flower than most acaule), E. cheilanthifolium (which they wrongly called petraeum crispum, and ‘Natasha’ (which is really cheilanthifolium ‘Bidderi’). So, I guess you are by now getting the picture, that there is a big problem with correct naming and identification of erodiums!

I potted them all up in a planter, so I could bring them in for the winter. They thrived outside in the planter, but they did not like coming in to the plantroom under lights for the winter. I lost three of them, with the only survivor being the E. cheilanthifolium.

The Erodium cheilanthifolium proved to be very hardy when planted in the rock garden and left outdoors for the winter. It has now lived through three Canadian winters! This is a species that is also up against a lot of wrong and confusing names. I was not only Wrightman’s that were calling it Erodium petraeum ssp. crispum, but I have come across the same naming on the internet. First of all, it is not a petraeum, and that is in fact an old name, as petraeum was changed to foetidum… And the crispum part… Erodium crispum is an entirely different species, looking nothing like this cheilanthifolium. Some garden centres around here can’t even get the wrong names right, and are calling it ‘crispa’!

This wrong name stuff makes it so hard for a novice collector to know what they are growing. Of course the internet does not help by perpetuating all these wrong names. There is also a trend in the commercial trade to re-name plants and market them as something new. This form of E. cheilanthifolium seems no different than the plant marketed as ‘Stephanie’.

It does not help the situation much when there are several naturally occurring variations of E. cheilanthifolium found in nature. I have made some illustrations to show the most common forms of E. cheilanthifolium.

This appears to be the most common form of Erodium cheilanthifolium found in the wild. Typical dark blotches on the two upper petals and some dark pink veining on the petals.

This form is often seen in the commercial trade. This is the form that has been called E. petraeum ssp. crispum and seems identical to ‘Stephane’. The lower two petals are usually all white, leading some to call this form E. cheilanthifolium ‘Album’, which compared to a lot of the naming, seems to be a good choice.

This form of E. cheilanthifolium has dark blotches that almost cover all of the top two petals!

Not all that common, but the blotches can go to this extreme, being on all five petals!

Then there is the other extreme… No blotches at all!

This is E. cheilanthifolium ‘Bidderi’, a form that can have one or more extra petals. Exact same habit as plants sold as ‘Natasha’

This photo shows variations of flowers that were all on the very same plant!

These three erodium species above, have a tie-in with E. cheilanthifolium, in that they do get confused with it. I have not been able to get hold of an Erodium glandulosum yet, but often see the name used on wrong plants. To be fair, plants of E. glandulosum can be just as variable in the wild as cheilanthifolium, The illustration here is of the most typical form. The colour is different from cheilanthifolium, but they do share the dark blotches on the upper two petals. A brand new book (on rock gardens) showed a photo of E. cheilanthifolium but called it E. gladulosum. I’m not sure they did much checking on their names, as an E. x variable was called E. chamaedryoides, and not only was the hybrid of chrysanthum presented as the species, it was written as ‘chrysantha’. Oh well, it was after all a rock garden book, not a monograph of erodiums… But no wonder it is so hard the get correct and up-to-date names into common use.

You can see how easy it would be to confuse a real Erodium celtibericum (above) with an E. cheilanthifolium form that had no dark blotches!

The pink flower at the right of the above illustration is the true Erodium crispum.

Erodium acaule as proved to be among the most hardy of any of the erodiums I have grown. It too has survived several harsh zone 4 winters. The flowers are not all that large but they are a nice clear pink, and they are produced all summer long!

Like all my erodiums, the Erodium acaule love it in the rock garden, where the soil is well draining, especially near the crown of the plant. This is very important in wet weather. This little plant produces seed easily, and once you have it established, you will always have some seed to harvest for backup.

This is a good point to show why these plants thrive in the rockery. Most plants that grow in alpine conditions have roots that grow quite deep. I like to keep the top layers well draining to prevent the crown from roting in excessive wet, but also providing water retentive soil and nutrients deeper down for the roots to grow down to. If you provide nutrients and good soil only at the top layers, your plant will develop a shallow root system that could cause the demise of the plant in times of drought or excessive rain.

Keeping in mind how they develop deep roots and send them down between rocks in nature, I use the deepest style of pots that I can find.

This cut-away view shows how I fill the pots with well draining mix and include broken pot shards to simulate the rocks that would be found in the natural ground of these alpine-type plants.

I have built a special area in my rockery for these pots. At the edge of a crevice garden section, I have a mini patio for my pots. The actual erodium plants can get the sunlight they need, but the pots are shaded and cooler. Black pots exposed to the sun can get very hot!

When growing any plant outside, there is always a danger that wildlife of many forms might find it tasty! Growing in tall pots, did not protect this erodium from being a snack for a rabbit… Perhaps that is the price you pay for having carrot-like foliage!

It’s not always little critters… The tracks in the snow clearly showed that this erodium (that had just survived a harsh winter) became a snack for a deer! I put some protection over it, and it re-grew it’s foliage. In many cases the over-wintered foliage eventually gives way to new foliage anyway.

These erodiums that I have put in the pots are seedlings from seed of John Anton-Smith hybrids, that I received from the UK. These are complex hybrids of dioecious (separate male & female plants) erodiums from the eastern Mediterranean. Those of us that have been growing these refer to them as the ‘blue erodiums’… Even though they vary in blueness, and can photograph quite pink.

I sowed my seed indoors (bright window with lights) and transplanted the seedlings into the tall pots when they were a size that was easily handled. They eventually got eased out into outdoor sunlight when all frost warnings were over in the spring.

As well as the variation in flower colour, the seedlings showed variation in leaf and stem colour. Some were simply all green, and some had light green foliage… Others had darker green foliage with red stems.

This separate male and female plant trait is the same for the previously mentioned Erodium chrysanthum hybrids. I’m hoping that eventually I will have my male ‘Moonman’ plants flowering at the same time as a female of the John Anton-Smith hybrids.

I was lucky enough to wind up with both male and female plants among the first year of John Anton-Smith seedlings. I simply put the pots close together and bring the flowers in contact with each other. I was successful in getting a few beaks to form.

Here is a little trick that you can do to prevent the erodium seed from flinging of the column before you can harvest it. A small bag twist tie or a piece of thread will keep the awns attatched.

Erodium seed is quite interesting in itself… The long awn stays attached to the pointed seed when ejected off of the beak. Depending on changes in moisture, the awn can curl up like a corkscrew.

When the seeds land on the ground, they start to unwind as they dry out, and the end of the awn will anchor itself on the groun or perhaps on a stem. As the awn continues to untwist, the pointed seed is driven into the ground… Planting itself!

Depending on the species, newly germinated seedlings can look quite different when they emerge.

The seedlings themselves can be quite varied. Not all erodiums have that ferny or carrot-like foliage. At the back centre is an Erodium trifolium and at the right is E. televivense.

Erodium televivense (above) and the very similar Erodium gruinum (below) are both annuals, and are not likely to be popular with the average grower. I have grown them off and on for several years and find them quite interesting. Perhaps this is because they are so rarely seen and certainly would never be offered in the commercial trade. They can sometimes be seen on lists of erodium seed offered by the specialty club seed distributions. Not only do the plants only last a year, but their flowers only last a day! As a matter of fact I have gone out to the garden and spotted one of them blooming, and rushed back in to get my camera, only to find the flower has dropped when I got back out!

These two are also erodiums that do not have the typical carrot-like foliage. They also have good sized, long beaks, with E. televivense having the longest of the two.

Erodium malacoides is an annual weedy type, that no serious gardener would want in their garden, but of course I have to give it a try! It does not have very big flowers.

Of course, I would never let ‘weedy’ stop me from growing a new erodium… I’ve even had a go with Erodium cicutarium… An almost worldwide weed!

Well, let me switch from unpopular weed erodiums, to one of the very best performing erodiums that I have grown. This plant came as seed from the UK, and the name ‘Sans culottes’ is given to seedlings from a popular erodium, ‘Robespierre’. They will vary slightly, but most will resemble the parent.

My seedling ‘Sans Culottes’ was planted out in the rockery in the spring as soon as all chance of late frost was over. This first bloom appeared in late May. At first glance the plant might appear similar to the well-known Erodium manescavii, but they are in fact quite different in growth habit. E. manescavii can grow quite tall, but ‘Sans Culottes’ is a very compact plant that hugs the rocks.

You can see that the foliage of the two is quite different.

Erodium ‘Sans Culottes’ has flowered non-stop from late May right into September! My fingers are crossed that it will also prove hardy here. It has produced some seed, so I do have some back-up in case it does not survive the winter.

This seed will produce plants that could vary even more, and they can’t be called ‘Sans Culottes’ as that name only applies to that first seed strain direct from ‘Robespierre’.

Oh well, that constant hoping for winter survival is certainly the main challenge of growing erodiums in Ontario.

• 3 Sep, 2017
• 8 likes

More blog posts by bowl_you