Sunday, 4 October 2015

Seed and Potting compost: Part 3

In Part 1 of this series I discussed composts made from green waste. Some are of high standard but others are inferior because of lack of quality control in the organic components. Although there is an issue of pollutants most of the problems arise from erratic levels of soluble content.

In Part 2, I made a case for the use of peat. Deeply unfashionable I believe the case against it is flawed.

In a much earlier post I discussed soil as a compost component when for example it is used as an ingredient of John Innes compost. I have also written of my own penchant for using my own coarse silt/fine sand garden soil fortified with slow release fertilizer as a complete compost. This is inappropriate for most gardeners because their soil has the wrong texture. Never the less I think that where gardeners are growing plants in tubs or large containers, perhaps greater than ten litres if they have high quality garden soil it is far superior to garden centre compost.

More about soil as a compost
Garden soil does contain weed seed and perhaps certain pests and diseases but this is no worse than when it is still in the ground. It does last indefinitely and does not decay away like organic composts. If recycled it does need refreshing with slow release fertilizer or when used to grow more permanent plantings such as containerised shrubs and small trees it needs regularly top dressing with compound fertilizer or liquid feeding.
This cut leaf maple has been in its soil for four years. It is top dressed with yaramila compound fertilizer about every three months
In some ways stripping soil from the land in environmental terms is worse than removing peat from wetlands. Much soil is available that comes from land stripped for building such as new roads or motorways. If it comes from such sources and is of appropriate texture such as soil from my own local area it might be very suitable. Unfortunately if you buy garden centre John Innes compost the soil component won't be prepared from turf as in the compost's original specification! No matter, neither is my own.

I have no environmental concern when I make compost from soil from my own garden because I either reuse it or return it to my ground.
My sandy/silt soil
Over the last ten years I have been genuinely surprised how good my soil garden compost is. The fine sand/coarse silty nature makes it very water retentive and I need to water it less frequently than normal organic composts. Better, the cut off between enough water and severe wilting is much more gradual than the sudden severe wilting of organics. Nutrition is excellent with slow release fertilizer and my plants are generally very healthy.
I do of course get pearlwort and liverwort on the unsterilized soil surface. It is easily removed.
Now going dormant my marsh helleborine is weedy with pearlwort
Liverwort is spread by spores. Both unsterile and  sterilized composts are equally vulnerable
Liverwort and pearlwort can be scraped off and put into the base of a planting hole or when potting-up recycled into the pot bottom. My weed seems very little worse than the gumpf growing on the top of typical garden centre plants.
(You don’t get surface weed from plant sales at the superstore, they kill their plants too soon!)
I am not proud of the scruffiness of this two year old daphne seedling that has been growing-on in my nursery all summer
I took all of five minutes to scrape off the surface and repot all seven fine plants
Peter Williams my scientist friend has been doing my watering this year when we have been away. Although he is scathing about my general irrigation arrangements I think he has been quite impressed with my soil pot-grown tomatoes. To my amazement he even mused about using soil himself for his own tomatoes – it is the same texture as my own.
He even said that some of the fertilizer he might use for his tomatoes in their final ten litre pots might include general purpose fertilizer! Although I recommend top dressing with general fertiliser that is a practice I have never dared admit to in writing this ‘plog’!

Making your own potting compost
Many gardeners prepare compost from garden compost! A contradiction in terms. In the UK we have the different meanings of the term 'compost'. It might mean mixes for sowing and planting or stuff from a heap. I expect in the old days the meaning was the same when compost from a compost heap was used to grow plants in containers. No doubt other organic materials such as leaf mould were used too.
Indeed I remember when as a garden apprentice the old foreman added leaf mould to his new fangled John Innes mix. Perhaps he was ahead of the game as we now recognise the value of mycorrhiza. Readers might recall that I think adding mycorrhiza from a packet is a complete waste of time.
My friend Peter makes the best of both worlds. He has huge amounts of leaves from his trees and mowings from his lawns. He composts them together and when they are well decayed he sieves them and adds fertilizer and lime to make his own mixes.
I remember an old colleague who in the early days of grow bags made up his own in a very similar way. Personally I don't like grow bags and when in the past I have used them for tomatoes I have tipped their content into ten litre plastic pots. I don't think long flat containers have as suitable properties of wetting and drying as do deeper containers.

Nutrients for composts

I am into my fourth year with my 25kg bag of coated slow release fertilizer
Whatever mix of bulky ingredients are used in making your own compost the amounts of fertilizer needed will be very much the same. Peat compost may need a little more lime or if you are strengthening a multi purpose compost a little less slow release fertilizer.

Dolomitic limestone is our favourite lime. It contains both calcium and magnesium
My own methods of measuring fertilizer might be best described as intuitive.
More credible are Peter Williams' ways. He has various measuring methods as short cuts to his target but in principal his formulae is very simple. He uses ‘coated’ slow release fertilizer at between one and three grams per litre of bulky content depending on his judgement of plant requirements. He uses lime for his peat composts over the same range of between 1.25 and 3 grams per litre.

Interestingly he actually uses lime at 1.25 gm/litre even for his rhododendrons that he grows in fertilized peat. This is perhaps because of the benefit of the calcium it contains. Unless a plant is known to need calcareous conditions he uses lime at only 1.25 gram per litre when he mixes his no-peat composts.
The slow release fertilizer we both use is one of the many controlled release coated fertilizers readily available these days.
The form of lime - if any is required - is ground limestone or ground chalk. Peter’s and my own preference is ground dolomitic limestone marketed as dolodust.

Other bulky ingredients that might be used as part of a mixture
A special coarse compost is needed for orchids
Some gardeners and commercial growers use bark. Use the type sold for potting rather than that used for mulching unless you are growing a large plant that prefers a very coarse mix.

Never again
Both vermiculite and perlite are natural minerals which in manufacturer are heated and exfoliate to light fluffy materials. In am personally not enamoured with either but some very good gardeners swear by them!
Perlite has a closed structure and does exactly the same as grit when used to create air spaces in a compost. It holds no water or nutrients and is completely inert. It's light weight might endear it for hanging baskets but in plastic pots tall plants are liable to topple over. I tried it recently in a mix for some special dicentra seed I had collected and was disturbed that my rather heavy handed watering almost washed my seed away. I can never find my watering rose!

I understand some gardeners get very good results sowing seed in pure vermiculite. Vermiculite has an open structure and will absorb water and does naturally contain some nutrients. It seems to me to be a fairly messy material and Peter too curled his lip at the thought of using it!
(You might have noticed I sometimes make dogmatic statements. Do not hesitate to contradict me in ‘comments’).
My soil compost was excellent for bedding these florist cyclamen from Aldi
Now what shall I do with last year’s cyclamen that are now fully established in soil?
This red saxiifage has made a fine root system and is ready to plant in Cathi’s garden
This bog plant likes my soil 
Grown in a six pack of loamless compost these rather chlorotic Harlow Car hybrid primulas were given to me last week. They will soon green up in my soil.

I love my soil composts
Some of you will know of my interest in terra preta and charcoal and biochar. I had intended to include biochar in this post as an ingredient in composts. I now find I want to say too much and will write about it in my next post.

Sunday, 27 September 2015

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 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! All my cacti are propagated inside in my 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

Sunday, 20 September 2015

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 cafĂ© 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 Yaramila fertilizer
Why one sack of compound fertiliser will fulfill most of your needs
When you should use peat

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