Although I’ve been a gardener for many years, it’s only since growing exotics became fashionable again that I’ve heard the word “Architectural” used to describe plants. (I put this down to having lived a sheltered life.)
Quite what the art and science of building has to do with plants is a bit above a mere mortal like me so I’ll leave it to those on a higher plain to figure it out.
For the benefit of those who take this kind of stuff to heart though, let me introduce you to some plants which according to all I’ve read about them are the very epitome of “Architectural”. The Yuccas!
Native to the Americas and the Caribbean, it’s the hardier species from North America which are of interest to most enthusiasts including me.
Depending on which book you read or website you access there are between 40 and 50 Yucca species and sub species native to the U.S.A. and Mexico.
Y.Glauca is one of the hardiest and it can be found growing as far north as Canada and from there south through the Great Plains into Texas.
It provides us with a useful demarcation line between the hardy and winter wet tolerant species to the east and south east and the hardy but less tolerant of winter wet species to the west and south west. (This conclusion is based on my experience.)
At the present moment I have a small collection of 12 species, the majority of which I’ve grown from seed.
Here’s a breakdown of the plants I’m growing now starting with the hardier types from the east/south east.
All of these are growing outdoors without any protection.
Y.Glauca, Y.Filamentosa “Gold Sword”, Y.Gloriosa, (and Y.Flaccida) are fully hardy and should come through the winter unscathed in most parts of the U.K.
Y.Aloifolia, Y.Gloriosa “Variagata”, these are also hardy but in my garden they’ve suffered some minor leaf damage.
Y.Gloriosa itself is something of an enigma.
I've seen it described as a zone 7 plant on some websites and a zone 9 on others.
Whatever its zone is, my Y.Gloriosa pictured right, which I’ve grown from an offset has turned out to be one of the hardiest plants I’ve grown suffering no winter damage at all.
Unfortunately, the same cannot be said about the Y.Gloriosa I’ve grown from seed.
Now small plants, they have suffered some damage to the leaves.
Compared to some of the other's I’m growing though, this has been minor.
The plants in this section are those I’ve grown from seed.
All are native to the west and south west of the U.S.A. and Mexico.
Many find their home in one or more of the 4 great deserts that are found in this part of N.America, The Mohave, The Chihuahuan, The Sonora and The Great Basin Desert.
From these dry semi-arid areas of N.America, come most if not all of the more spectacular members of the Yucca clan.
Y.Brevifolia "The Joshua Tree" largest of all the Yuccas and a magnificent plant which really does grow to tree like proportions.
Native to the Mohave Desert, it has a National Park named in its honour.
Y.Whipplei from California (Baja) and Mexico is best known for its giant stem packed with flowers hence the popular name "Our Lords Candle".
Finally, from the Great Basin Desert comes the smallest of the Yuccas, Y.Nana.
Found in only one area of Southern Utah, Y.Nana was only discovered in 1985.
Described and named in 1998 it has been given species status but this in itself, has caused some disagreement among experts over its validity.
In between these examples, there are a host of other equally magnificent plants deserving of a place in anyones garden.
The names of the plants I'm growing now are listed below together with their U.S.D.A. zone rating.
Y.Baccata (5), Y.Brevifolia (7), Y.Carnerosana (8), Y.Elata (7), Y.Rigida (8), Y.Rostrata (8), Y.Torreyi (8).
If like me you're overwintering small plants outdoors, then I'd advise you to provide them with some form of cover to keep the worst of the elements at bay.
Failure to do so will almost certainly result in leaf damage and in severe cases, the loss of plants usually through the roots rotting.
This is due to the fact that these Yuccas come from areas where they have cold dry winters where as here in the U.K we have cold wet winters.
(How winter wet affects the large or specimen sized plants that are popular nowadays I don't know for the simple reason that I've never bought one.)
If you bring you're plants indoors to overwinter them, then beware of Red Spider Mite as this little beast can do considerable damage to young plants.
There's no great secret to growing Yuccas just two essentials, Sun and excellent drainage.
With some of the hardier species from the East/S.East you might get away with light shade and a slightly moister position.
However, I've found that species from the West/S.West aren't so accomodating and at least with me, they've proved to be very intolerant of excess moisture, even in the Summer.
With these latter species, if they're planted in positions where there's constant dampness, root problems, particularly rotting are an ever present danger and these are difficult, almost impossible things to cure.
A south to west facing position in well drained soil is o.k. for the eastern species, while the western species need as much sun as you can give them, a south facing spot being ideal.
If you live in a cold area, planting them against a south facing wall will help give them some protection from the worst of the elements as these areas tend to be a bit drier than the open garden.
As noted above, I've found that the ability of the soil to dry out quickly is critical for the western species and for those whose gardens have less than perfect drainage, I'd definitely recommend building raised beds.
There are those who advocate digging in piles of gravel to improve the drainage, but if like my garden clay makes up a large part of the soil, then to my mind you're simply wasting time, effort and money.
Some of the eastern species make attractive pot/tub plants for the sunny patio with Y.Gloriosa variagata and various forms of Y.Filamentosa being popular.
I prefer plain clay pots for larger plants, only using plastic when I’m growing plants from seed or offsets.
A straight mix of half and half J.Innes no2 or 3 is fine and if you want to add more gravel, then it won’t do any harm.
If you use plastic or glazed pots, then increase the amount of drainage material.
Remember, unlike plain clays, plastic or glazed pots do not “breathe” so water takes far longer to evaporate, the compost must dry out quickly otherwise you could get problems. Posted by Mike