Agaves

The agaves that we grow and are used to seeing are those found in North and Central America.  Some come from subtropical regions but most are from deserts and as such are used to minimal rainfall and high day time temperatures - during winter many species see night time temperatures fall way below freezing.  Quite often this paltry rainfall is seasonal, unfortunately for us it tends to fall in either autumn or spring, so the plants are used to having dry weather to accompany the cold.  To overcome this when growing in the UK the plants must have perfect drainage, good air movement and maybe some overhead rain protection.

Some species have shown they can adapt to a greater rainfall pattern - Agave celsii var albicans, salmiana var ferox and americana will all grow well in the wet west country, but this is in conjunction with, generally, milder temperatures.  What the precise relationship is between cold and wet tolerance elsewhere in the country is something that can only be found out by trial and error as no-one seems to be growing many.  Agave parryi and it's forms is one that has something of a proven track record for a good balance of cold/wet tolerance.  Others eg Agave utahensis are extremely cold tolerant when dry, others eg Agave celsii var albicans are extremely wet tolerant when warm !

The following is a small selection of agaves that are more likely to be encountered - there are dozens more.

This is the most commonly encountered agave.  It gets quite big, 1.5m -2m across on mature plants, grows fairly quickly for an agave and offsets like crazy.  Larger plants are quite cold tolerant, and once the size of a dustbin should be able to remain outside.  In the mild wet conditions of the west country they seem to do well, in the drier colder parts of the country I don't know, but I think anywhere they are planted out they need good air circulation.  I have heard of people in the north of the country growing them to a good size when planted out  by covering with plastic to keep the rain off.  Eventually they will flower, but I have only seen one flowering in the Scilly Isles.  Plants are variable from different sources - some are quite glaucous and silvery, some have very broad leaves - there are distinct sub-species in the wild - so shop around and you will get some nice variations.  There was a particularly nice silvery form distributed a few years ago in the trade as Agave franzosinii - it wasn't A. franzosinii but a nice plant nevertheless.  None of the following variegated forms are as hardy as the plain species. ( 1999 )

I know this plant as having irregular but distinct bands of creamy-yellow that aren't restricted to the leaf margins, and the leaves are narrow and wavy.

This is the one I grow - it has yellow variegation that shows mainly on the edges of the leaves, which are themselves broad and slightly recurved

I have only just managed to get hold of this - it is rarely seen in cultivation.  The colours are the reverse of 'Marginata' in that the leaves have a yellow central band.

This is similar to the above except that the central band is pale cream to white.  It remains quite compact and is often difficult to track down.

This one has very thin streaks of yellow distributed throughout the leaves, not just confined to the leaf margins or a central band.  Again, rarely seen - even more rarely offered for sale.

An extremely tender agave that won't take any frost at all ( I have lost it in an unheated polytunnel at around -4°C )  but is absolutely gorgeous.  Pale powder-blue rosettes that can reach 80cm across and also forms a trunk.

This is a small colony forming agave with dark green rosettes and leaves edged with neat rows of tiny dark teeth.  It seems to love the growing conditions in the southwest - enjoys the high rainfall but doesn't enjoy low temperatures.  It also flowers quite regularly too.  Not sure how it will grow in colder areas. ( 1999 )

This is a nice chunky agave with pronounced teats....yes, teats, and leaves become attractively banded horizontally as the plant ages.  May be quite hardy. ( 1999 )

This is a chunky agave with very thick and rough textured grey leaves and small teeth.  It should be ok in the cold, but as usual not sure about cold/wet. ( 1999 )

A very pretty agave that forms a dense hemisphere of fresh green leaves about 60cm across and with loose hairy filaments along the leaf margins.  I have left this outside in a pot and it has gone through -7°C with minimal damage, so now it is planted out I am quite hopeful it will prove to be quite hardy. ( 1999 ) 

This is absolutely gorgeous, with almost luminously silver glaucous, yet coarsely textured leaves that are strongly recurved and twisted.  A monster plant - one of the largest agaves that can reach over 3m high and even more across.  The large silver plant in the arid part of the Princess of Wales Conservatory at Kew labelled A. americana is in fact this beauty.  Hardy ?  Maybe.  Available commercially ?  Hardly ever.  I am lucky enough to have finally tracked down a small plant of this which should be big enough to plant out in a couple of years.

Small, stocky-leaved agave; dark green with a lighter central band.  One of the marginate agaves with a horny leaf margin from which arise the teeth.  A bit like a condensed version of the univittata/lophantha. ( 1999 )

Broad leaved, grey green agave forming rosettes around 1m across in time, this is related and similar in appearance to Agave parryi.  It should be quite cold and wet tolerant. ( 1999 )

This is related to Agave salmiana var ferox and, if anything, should prove to be even better to grow in cultivation.  Gentry ' ...a high, montane species...generally between 2150 and 2800m....snow may fall at these elevations....it is a mesophyte, requiring relatively high rainfall, cold hardy and tolerant of some forest shade.'  It is large, with dark green, narrowly triangular leaves that are very broad at the base and armed along the margins with  large, prominent teeth.  In other words, sex on toast.  Is it available commercially ?  Nope.

A smaller, thinner leaved, freely-suckering relation of Agave parryi that should be fairly cold and wet tolerant. ( 1999 )

This is a good prospect for growing outdoors.  It forms a magnificent, dense rosette about 1m across of pale green leaves that are fairly narrow with quite straight margins and slender reddish-brown teeth.  It should be quite cold/wet tolerant and high up on a list of suspects. ( 1999 )

Another compact agave related to Agave parryi that has very short broad leaves that form into a spherical 'globe artichoke' shaped rosette.  This is one that has been grown outside in several gardens in the south of the country for a few years. ( 1999 )

This is possibly the best all round agave to grow outside in UK conditions and actually has something of a track record for being grown other than in the southwest.  It is tolerant of cold, down to -20°C it is said, and also wet - some forms grow in regions that have winter rainfall.  Although not a large plant, it is by far one of the prettiest with many different forms being in cultivation.  The type species has broad ,blue-green, glaucous leaves and grows into a densely leafed rosette - another globe artichoke - about 60cm across. ( 1999 )

This form is larger overall, and has fewer, thicker, more pointed leaves. ( 1999 )

This form is possibly the prettiest and makes me sigh in admiration when I see pictures of large specimens - I have only seen one full-sized specimen in the flesh and that was sadly rather tatty - with very wide, blunt-tipped leaves that are even more 'globe artichoke'-like than the others.  This is the one that is normally seen pictured in RHS books under Agave parryi. ( 1999 )

This form has very broad but also extremely short leaves - sometimes broader than long - so the rosettes look even more squat and round.  Rarely seen, even more rarely offered for sale, absolutely gorgeous.

Small clustering rosettes of dark green leaves, with white 'bud printing' lines and threadlike margins.  Very pretty, will probably need to be kept as dry as possible.

Not very hardy, but a gorgeous plant nevertheless, with very broad blunt tipped leaves and extremely prominent teeth and teats ( the 'fleshy swellings' under the teeth ! ) all finished in a nice powdery blue-grey.  There is a plant sometimes encountered Agave verschaffeldtii that is said to be a form of this species.

This is fairly widely grown in the southwest and is an absolute stunner.  It has very broad, very thick, very tough leaves in a very dark green, very large teats ( see above ) and large teeth and grows into large open rosettes maybe 2m across.  Large, really.  One of the most architectural and one of the best (1999 )

Related to Agave parviflora, longer leaves with thread margins, no white bud printing lines.  Cute.

A fairly meaty agave with thick grey-green glaucous leaves that are broadly sword-shaped narrowing at the tip to a long fine terminal spine and edged with reddish brown teeth.  Very attractive and architectural, should reach 1.5m across eventually. ( 1999 ). 

A large, smooth edged agave farmed commercially as a source of the fibre sisal.  Hardiness is doubtful but untried. 

A porcupine of a plant, with dozens of thin, stiff, rapier-like leaves that are tipped with un-yielding spines.  Within a short time it will cluster in a ferocious colony.  Looks magnificent and should be quite cold tolerant. (1999 )

Large attractive agave with small teeth along quite stiffly held straight leaves and a short woody trunk.  Glaucous pale blue-grey.  Hardiness not known.  Listed for curiosity value really as it is the main commercial crop plant used in the production of the drink tequila. 

A medium sized agave that is extremely robust looking - very thick leaves, very pronounced teeth and teats - which should develop in maturity a heavily glaucous covering so as to appear almost white.  Looks lovely in the pictures, my seedlings are nothing like it at the moment.

These are often seen as separately named plants but are treated as being  synonymous by Gentry.  I have raised seedlings of both that are to my eyes identical - extremely similar to those named as lechuguilla as well, incidently - and they are all have straight dark green leaves with a central pale band and marked with even darker longitudinal dashes, wavy margins to one extent or another and a horny, woody margin from which the teeth arise.  Very attractive plants, whatever they are called, and should be quite hardy. ( 1999 )

This is a very small and variable species that has grey rosettes of narrow, straight, pointed leaves eventually reaching 30cm diameter.  The type species offsets freely, has a long, drawn brown terminal spine and small flat teeth.  It has the dubious pleasure of being the most cold-hardy of all agaves, enduring temperatures of below -30°C in it's native desert habitat. ( 1999 )

A small form distinguished mainly by having a very elongated ivory white terminal spine.( 1999 )

This is the largest form with rosettes reaching 45-50cm, slightly greener in colour than the others.

This is the smallest and hardiest clone - very blue-grey in colour and with more prominent teeth. ( 1999 )

A densely clustering, small species that has distinctive angular stubby leaves of a dark green with white bud printing lines on the edges.  No teeth but a short sharp terminal spine.  There are several variants in circulation - including a rare variegated form - and some are encountered under the name of Agave fernandi-regis.  Should be quite hardy.  ( 1999 )

A personal favourite, this forms a densely clustering group of dark green rosettes with a pale central band and ferocious looking large horny teeth on the woody leaf margins.  Superficially similar to the lophantha/univittata brigade but loads more attitude.  Should be hardy ( 1999 )   

 

< index-aloes  >