Growing hardy cacti outside in the UK

Home on the range

This opuntia was completely undamaged by 18 degrees centigrade of frost for three weeks in 2010

You might think growing cacti outside all the year round was nye on impossible in York! You might be right!

For several years now I have had a degree of success with growing cactus outside. Cactus were my childhood passion!

My first plant ever was a cereus barrel cactus. It was quickly followed by the succulent Sedum rubro-tinctum, a rather insignificant plant but one that fascinated me because the globular succulent leaves would root and then grow. It is easy to forget the thrill of rooting ones first cutting. I subsequently grew a dozen or so cactus for several years in my parents barely heated conservatory. When I went to horticultural college I put such childhood things behind me. Marilyn my sister took over my collection and it's remnants survive in her house to this day!

Now in my dotage I have been growing cacti outside for several years.Today, I am being rather self indulgent. Hardly anyone shares my interest and nobody read my previous post. What is the point of having a blog if I cannot write for myself?

All these have proved to be hardy and have been completely outside for several winters now

Just occasionally a visitor shows an interest. Cactus growers are very peculiar and dedicated people. I love them all, they are fascinating folk!

Allan in Orkney used to grow magnificent cactus at Askham Bryan College. He is my editor in chief and I regularly receive an e-mail missile with my latest spelling mistake which I immediately change. I had better watch what I say today!

About my indulgence

I originally researched on the net about hardy cacti and discovered there were several sources such as the Cactus Shop. I mean true cacti and although I also grow other succulents they are not my subject for today.

Unfortunately the Cactus Shop lumps cacti and succulents together.

Cacti are all members of the family cactaceae and include the very different desert and epiphyte species.

I discovered that certain cacti are very cold hardy indeed, coming from very cold places such as high in the Andes. Such habitats are either very dry in Winter or are under a blanket of snow. The difficulty of growing cactus in the UK is winter rainfall and high humidity. Worse the fluctuating conditions of moisture and temperature. If cacti don't like their Winter conditions they soon turn to mush!

The site that I chose was at the foot of the south wall of the house. Desert cacti must have lots of sunshine. I judged that the slight overhang of the roof would to a small degree shelter them from the worst of the winter rain. No matter that the site was a hardcore path! This was my most successful site but with hindsight had the soil had been a little richer but still very well drained, my cacti would have developed more quickly. Desert conditions although dry can be surprisingly fertile.

This really is quite deep hardcore covered with gravel. I do infiltrate a little soil when I plant

I have perhaps a dozen different cacti that have successfully over wintered outside in my garden. Some for several years now. Opuntias, the prickly pears have been the most reliable bankers. I emphasise that they need to be carefully selected. Those from the garden centre are unlikely to survive outside. I did however recently increase my stock of Notocactus leninghausii at Aldi!

Both the notocactus and the echinopsis are lifted into my cold greenhouse for the worst three months of the winter

Although I continue to grow many varieties completely outside, for others I have changed my technique. I bring them into my unheated greenhouse from mid December until the end of March. They love their nine months outside and grow better than any left in the greenhouse but by giving them this mid Winter protection I can grow a wider range of varieties that thrive.

I just dig them out in mid December using a hand fork or spade. Indeed because of their nasty spines anything other than my hands! I no longer plunge them in pots when I plant them and it is a very speedy operation to deposit them loosely in pots or plastic seed trays and to prop them vertical with extra soil when I bring them inside.

They will remain like this unwatered for three months. This notocactus is said to only survive four degrees centigrade of frost but it has survived two winters now

When lifted their roots will usually be wet. They will receive no more water until a week or so before they are planted outside in March. The time of planting varies a little with variety, nature of the season and whim. All I give them in Winter is an open unshaded position in my unheated greenhouse.

Unheated greenhouses in the UK are described as cold greenhouses. They will usually be several degrees above outdoor temperatures especially when the cold outside lasts for a short period such as a single cold night.

Where there is continuous severe cold over long periods in Winter (unusual in these parts) then the cold does penetrate and the inside of the greenhouse will be similar to outside. In the exceptional Winter of 2010 my greenhouse temperature was – 15 degrees C for several days. The benefits at such times are wind protection and dry conditions. As there is no internal heat source in such circunstances bubble insulation is useless. Some of the truly hardy cacti withstand down to -20 degrees C.

Outdoor management

Cacti have simple requirements providing they have plenty of light. Good drainage is essential but ordinary well drained soil is absolutely fine. Don't waste money with cactus compost when any gritty mix will amend a heavy soil. Because yanking out once a year rather restricts their roots I do sometimes water them in dry spells in Spring. I also water the ones permanently planted under the roof overhang. I also feed them by top dressing with my usual NPK fertiliser - especially those growing in my hardcore!

Pictorial post

Readers will know of my admiration for hybrids! The fragile pads sometimes become detached and will root to rapidly increase clump size

The flowers of echinopsis are only open for a couple of days A huge range of colours are available

Brenda criticizes me when I let nigella seed everywhere! In this case she is right as it is important that cacti receive the maximum light. Any volunteers for weeding? Try a trowel

You might imagine fine hairs exacerbate problems of wetness. They seem to do the opposite

This opuntia permanently thrives well in full sun in ordinary garden soil.

Hardy opuntia associates with sempervivum, creeping thyme, dwarf dianthus and heuchera

New plants are easily propagated from pieces merely popped in! Most of my cacti are propagated inside in pots of my ordinary sandy garden soil

I later pulled the competing delosperma away

All my cactus have a gravel mulch which is said to be beneficial with regard to Winter wet

Rooted Maihuenia poeppigii cuttings planted to make a ground cover. It is the hardiest cactus that I know

This picture is for Po Simpson (the moonshot man). The name might suit him!

Silver torch or woolly torch cactus stands 10 degrees of frost but won’t stand Winter wet

Mistakes I have made

I originally bought about sixty different hardy cacti from a range of suppliers. All small plants. Cacti on the net are really quite cheap and I spent no more than £200. Some were no more than unrooted cuttings and as a Yorkshireman I only buy one plant of each!

I attempted to remember their names and failed.

I now regret leaving several outside for the first Winter when they were still very small. Most turned to mush. Larger plants seem to do better and before risking them I should have propagated spares in my cold greenhouse.

Although echinopsis need to be brought into the unheated greenhouse in Winter many fine varieties are available and I should have tried more. It’s not too late!

I did push the barriers with regard to sunshine and lost some to poor light. Only the maximum will do.

Although it was not necessary to amend my own sandy soil, I do recommend that gardeners with heavier soil amend it with grit and coarse sand. It is often beneficial to create a raised bed and plant on the plateau. I think had I planted in my sandy soil rather than retain my hardcore at the base of the house my plants would have faired better.

My only wall with the root overhang actually faces south/south west. A significant difference from south. We get superb morning light – a south/south east aspect would be excellent. Unfortunately it often clouds over by lunchtime. Worse a few of my shrubs cast a little shade when the sun is low in the sky. It is really important that cacti are in full sun.

I really feel at home on the range

More about my hardcore

I have added a link on how Edinburgh botanic garden grow hardy cacti in a simple plastic shelter

A visit to Four Oaks Nursery Trade Show

Boy’s day out

Peter suggested that I might like a trip over the Pennines to the trade exhibition and I jumped at the chance. The main show of the year for the nursery trade has been held on the same twenty three acre nursery site for 46 years now. It must be thirty years since I have been to anything like it. Just to see a huge area covered with modern glasshouses is exciting and it is a revelation to see methods of modern large scale production.

We drove down to Bakewell and deposited Julie and Brenda. We would later retrieve them in Buxton at Peter’s daughters'.  We enjoyed a coffee before leaving the girls. When we asked the café owner if he sold Bakewell tart he replied in the negative and claimed to have been out with too many!

We were then on our own and talked gardening, horticultural science and blogging none stop all the way over. Peter’s sat-nav took us a delightful rural route and the first evidence of the show was when we arrived and joined the huge car park of thousands of cars in a huge field next to the Jodrell Bank telescope. I dread to think how they must manage all those cars after heavy rain.

Everyone in professional ornamental horticulture goes. The garden centre and nursery traders order their plants and sundry supplies for the year. Horticultural producers meet their suppliers and purchase their materials and equipment. The displays are as lavish as Chelsea. Nursery suppliers from all over the world are there. Forty percent of nursery stock now comes from Europe and every large European wholesale nursery has a presence.

Everything was on a large scale and mainly under cover of glasshouses. Here 'Juakali’ displayed more than a hundred African inspired model animals

Much horticultural production now takes place in huge specialized nurseries. In some cases we are talking about millions of plants and growing methods are extremely refined. I think many amateur gardeners seek to copy the commercial trade’s methods and in my opinion this is ill advised. For example the trade’s choice of fertilisers and composts are extremely precise. Efforts by the amateur to duplicate this is both uneconomic and ineffective. Many ‘special composts’ and ‘targeted fertilisers’ available at the garden centre are inferior and inappropriate and hugely expensive.

Nor would I advise amateurs to attempt grower’s extreme hygiene and prophylactic spraying! As to mechanized irrigation, give me a can and a hosepipe for the wide range of plants I grow. All have very different watering requirements. I feel many gardeners play at being professional.

A taste of the show

Machines can pot several thousands of plants in an hour

The proprietor of ‘Weathervane plants’, aka Peter Williams is a keen grafter and admired these magnolias. He really did once have his own nursery and his plants are wonderful value and are sold at his May Open day and other Open Gardens in Yorkshire

Success or failure of newly bred varieties often these days depends on whether they fit and travel well on a Dutch trolley. New varieties tend to be shallow!

See what I mean. Colourful new varieties on Mole Seed’s stand.

Modern environment control can be very sophisticated. To me it’s a fog

The displays are of the standard of Chelsea. Although tens of thousands attended there was plenty of room to step back to take my pictures

Many stands displayed high quality conifers. It looks that these fine plants may be returning to fashion

I understand that these are part of the proprietor’s private collection

The catering facilities were excellent and cheap. Note the sophisticated shading system that can be turned on or off at the press of a button

Modern potting machines pot many thousand plants in an hour

Few good college horticulture courses are available these days. Hadlow College has an excellent reputation. When I retired I had a very happy time when I worked for them on their then contract to educate Homebase garden centre staff

Yaramila fertilizer is the general fertilizer that I use and recommend. Although the trade has the choice of many different analyses and variations just one general analysis purchased in 25 kg bags at about £25 is the best policy for we domestic gardeners for almost all of our fertilizer needs.  Ordinary garden centres do not sell it!

There are many fine hydrangeas available these days

Although amateurs eschew peat composts they are widely used in the trade.

Plant breeders have not yet produced varieties of impatiens resistant to downy mildew but so few are now grown that if you plant them they are not very likely to become infected

Let’s hope that box caterpillar does not make a visit

I could not resist a second picture of box topiary

Lovely carnations

Not my kind of thing but very impressive topiary

This reptile would look great with my giant ten foot high gunnera

We fell in love with her

Jim at Mole Seeds

There is a sub story here! Back in Bolton Percy, Jim sought me out when I was working in the cemetery garden early last year. He had just moved into my old house in the village. He took me back for a coffee and gave me a tour of the house and garden. It emerged he worked for Mole Seeds. Although their main market is commercial growers they also supply amateurs and their minimum order is pre vat only ten pounds. They have a brilliant catalogue and instructive web presence. Their smallest and extremely generous packets cost a little more than other seedsman but I take the view that virtually all seed is viable in at least the second year. Fifty F1 hybrid tomato seeds, for example, at perhaps four pounds a packet lasts me ten years.

I asked Jim about the cowboys I have recently discovered selling repackaged seed on the net. A dubious practice but tempting at 99 pence for a packet of ten F1 hybrids.

Things go full circle and Jim is now one of the keen and knowledgeable volunteers who help me in the cemetery garden.

I call him Mr Mole!

'Mr Mole' posed for a picture

I should have tried Mole Seeds’ sample tomatoes and found if they were as tasty as my own

The chief buyer for ‘Brook Horticulture’ kept his wallet closed

You might like to read about

My own lack of hygiene

My Yaramila fertilizer

Why one sack of compound fertiliser will fulfill most of your needs

When you should use peat

Ode to digging

There was a lot of digging to excavate my pond. When I made my borders there was no cultivation at all but some soil was used to raise their levels

No, I have not changed my spots but there are elements of gardening where digging is needed or at least is highly convenient. I will try to tell my story without my usual caveats that excessive soil disturbance is a very bad thing.

Visitors to my garden express surprise that the garden has been made without prior digging. They imagine that a no dig gardener never used a spade.The garden was never ‘dug over’ but I did use a spade!

I have published a whole series ‘why gardeners dig’ where I discuss the many procedures such as planting that requires soil disturbance. In these articles I have taken a rather broad view of the definition of digging and have included references to any deep soil disturbance whether it be ploughing, rotavation, burial or just digging holes! Today in justifying digging I confine myself to ‘real’ digging, a procedure that usually involves ‘turning’ the soil when preparing a plot.

Digging is perhaps part of the essential education of a young gardener. How else do you teach him a love of the soil? He is not ready for the sophistication of leaving things to nature or controlling weeds with herbicides. These things are long term and for motivation you need instant gratification. Not only can digging itself be highly enjoyable, it gives immediate opportunities for such as planting a border. I have found that in many things in my life I have learnt ‘the basics’ only to modify or discard them as I have learnt more. My bridge partner teaches bridge to beginners but you should see how she actually plays!

Students plotting

The students on the course I ran at Askham Bryan learnt a great deal about basic horticulture and how to grow plants on their individual plot which they maintained over the whole academic year.

Every year the plot transformed from absolute magnificence when it was judged in June to an overgrown wilderness over the Summer vacation. For the new students in September the transformative capacity of digging was certainly needed! All that debris and those magnificent weeds!

I have to tell you that the teaching methods of one of my colleagues - the student’s practical instructor - were positively Victorian. Imagine Mr Squeers with a gardening class! It is a strange thing that a man who many of the students positively hated would in later years be recalled with nostalgic memories of how much they learned.

Their thirty square meter plot had to be two thirds single dug and a third double dug and the students were assessed on their work.

Woe betide anyone who

1. failed to take their opening trench out to the correct dimensions
2. failed to separate the weeds when the trench-soil was barrowed to the place of later trench closure
3. parked their finishing pile in an inappropriate place 
4. failed to completely bury weed skimmed into the bottom of their trench
5. filled the trench with insufficient manure
6. failed to invert the soil as they dug
7. did not dig to the full vertical depth of the blade of their spade
8. lost their levels
9. failed on completion to have a pristine plot of completely weed free clods of soil
10. was slow!

For anyone unfamiliar with proper digging, each time a new trench is retrieved and after skimming in weeds and incorporating any bulky organic matter it is covered by soil achieved by several passes neatly turning the soil in,  The size of each bite will vary with soil conditions and the strength of the gardener.

If that is real digging then most gardeners do not dig properly!  Many gardener’s so called digging is so shallow that it is virtually minimum cultivation!

I have had experience myself of a foreman with very high standards when three of us dug a two acre plot on Hartlepool Parks Department nursery. I was in my ‘practical year’ before college. I can confirm that it is a healthy and hugely enjoyable experience. My horny handed fellow digger was an absolute craftsman. His digging was a joy to behold! He was the one who ‘turned’ the soil every year in the park!

The raison d’être for digging

In the days before herbicides the only way to control weeds was by cultivation. As agriculture developed over the millennia, weeds evolved to exploit the new niches created by man. Because of weeds crop yields were only a small fraction of their potential.

One of the greatest advances in managing weeds was when in the seventeenth century Jethro Tull promoted the use of deep ploughing and ‘clean cultivation’. Inventor of the seed drill he was a landowner and musician. He transferred his knowledge of the working principles of musical instruments into his inventions of methods of tillage. Ironic now that if you google the great man of agricultural history you need multiple pages to get past his more recent musical namesake.

To enable Tull’s soil surface preparation and mechanical hoeing prior ploughing or digging was at that time essential.

Advantages of digging

My above ramblings hint at some of the merits of digging. In particular digging’s ability to transform a weedy plot into pristine condition in a day. Farmers, landscapers and many allotmenteers all benefit and indeed frame their methods on this concept.

Digging is healthy and enjoyable and an excellent introduction to gardening for the young.

Many new gardens have compacted soil. It is sometimes  a result of plough pans from previous farming or more often builders’ excesses. There is a case for single or double digging. Just once.

I am rather ambivalent as to whether on such sites you can leave it to nature and the passage of time to correct this severe defect. I think I am persuaded that a deep cultivation might sometimes be needed.

Sometimes a new site might have buried rubble and dumped debris which might need to be dug out. Occasionally previous usage might have introduced a layered structure of soil or gravel or clay or sand. It will need mixing  together by cultivation. Similarly if you are amending your soil with bulky material such as gravel, woody prunings or in my case newspaper or charcoal it needs to be dug in.

In praise of the spade

All my spades together, a very rare event as I am usually unable to find them all at the same time

I have mentioned before when a Bolton Percy resident proclaimed in mock horror ”you - with a spade!”

Spades have many uses other than digging! In fact a small stainless steel border spade is my favourite and most versatile tool. Someone once questioned my judgment and suggested that an ordinary steel spade is sharper. I agree a very sharp edge is occasionally useful but with my levels of maintenance an ordinary steel spade would be both rusty and dirty!

My favourite spade is stainless steel, metal and plastic and was bought at Tesco! Note the rim of the blade which is very foot kind

When I cannot find  the stainless steel one I use this

In sheer desperation I use this unfortunate purchase which is falling apart

I have decided to list the multiple uses of a spade! Not just as a game but as a vehicle to illustrate various aspects of gardening.

I use my spade for each of the following

a) In emergency in someone else’s garden to create a new feature or transform a border within a day.
b) Make and restore an edge on a lawn.
c) Insert vertically and ease out a tap root.
d) Dig something out such as a potato or a carrot or a hunk of concrete! Indeed things too numerous to mention.
e) Make a slit or a hole for planting.
f) Undercut soil or a sod to pop under a handful of bulbs or a seed potato. If the propagule is not upright that is quite immaterial. No bulb planters for me. Never!
g) Lift and cut turf.
h)  Make a hole! When we moved into Boundary Cottage I dug out my two very large ponds. I moved six barrows a day for all of three months.
i) Ditto above, I moved six barrows of soil every day for three months shifting soil left in piles by the previous owner. In both the latter cases I used  the soil to elevate borders and fill in the dreadful cut out sunken rectangular ‘borders’ that I inherited. To put precious soil in a skip and throw away is an unforgivable sin.
j) Slice away moss or liverwort - both gifts of minimum cultivation
k) Use as a hoe where a dutch hoe is not to hand or where a heavier momentum is needed to avoid pain when I might jar my arthritic wrists.
l) As an inferior substitute for a shovel when scooping up molehills, collecting sweepings or mixing compost.
m) Levering out stumps or roots. I have lost many spades this way!
n) Propagation of herbaceous perennials and certain shrubs by division. It’s my favourite way.
o) Chopping things.
p) Slitting out shapes in a lawn before spraying off with glyphosate to later make a border.
q) Move and plant plants.
r) Break up compaction.
s) Move soil to create a level
t) Root pruning. For me this is a theoretical notion but in the old days fruit tree rootstocks were cut to reduce tree vigour. 
u) Nurserymen sometimes cut and undercut open ground plants months in advance of lifting. So can the gardener who anticipates future moving of a large shrub or a small tree.
v) Banging sticks and stakes in the ground! Better to use a hammer!

If anyone can take me to the end of he alphabet, please help!
Enough is enough. I have irretrievably destroyed my reputation.

Further reading
All my previous thoughts on good and not so good reasons for digging or other deep soil disturbance can be found by clicking ‘Why gardeners dig’ in my theme column on the right. 

You might be also interested in ‘Digging in manure on Christmas Eve’ and about Natural Selection of weeds in my ‘Musings from York’