My hydrophobic sandy soil

My sandy soil has an unusual property

Brenda says I agreed to move to Boundary Cottage because of the sandy soil. Rather unconvincingly I deny it and claim to not have even dug an inspection hole to see what I was getting. She says I had clients in the area and I knew!

I did know that the sandy soil would  increase my portfolio of plants, adding acid lovers and borderline tender subjects and those needing excellent drainage. I did envisage a huge range of new opportunities but not new constraints! 

I can now grow acid loving Wych Hazel

Sandy soil is reputed to be well drained, have low water holding capacity, have naturally low organic content and be subject to leaching. Mine did not tick all the boxes and because the particles of sand are very fine it is pleasingly water retentive when wet. The significance of this proviso will become apparent. Although I describe my soil as sandy - and if you dig down a couple of spits it is pure sand - there is actually some local dispute as to whether it is sand or silt. It depends on what diagnostic system you use. Is it fine sand or is it coarse silt? We speak of nothing else! The local soil certainly makes excellent agricultural land and much of the nation’s turf is produced in this area.

I have mentioned before that my minimum cultivation techniques have less advantages on sandy soil than on clay and I did have some unwelcome discoveries. It is amazing what surprises you get when you move form one garden to another. Some plants that are superb on one soil, will hardly grow on another. Different nutritional values make such a difference. Although lovely here at Seaton Ross, my Autumn anemones will only grow two foot high, whereas at Bolton Percy they make a magnificent six foot tall. ‘Easy’ monarda, achillea, hepatica, hakonechloa and skimmia hardly grow at all. You have to adjust your techniques in a new garden, What works in one garden is less successful in another. 

Japanese anemones in Bolton Percy soil.

My less welcome surprises included finding a small part of the garden was a natural podsol with a hard iron pan. (Well,in truth, for a mad horticulturist, it actually was quite crunchy and a fascinating horticultural challenge). The worse surprise was that my lovely water retentive soil when very dry would not easily wet.

How I made the discovery

I planted some one year asparagus crowns alongside my vegetable garden. It is slightly raised from the path. Not the fashionable raised bed that looks like a timber yard and ironically had it been one, the wooden lip would have prevented water being cast off. I have never seen young asparagus grow so well and I was starting to envisage only two years of establishment before I could crop. Disaster, hardly a shoot emerged the following year. I dug up a plant, the soil was dust dry. Not just dehydrated, like at the end of the season, it was as dry as a bone. There had been no wetting up by the heavy winter rain. No water at all!

I had already noticed that when my soil surface was dry I could not  easily water-in newly planted plants as the water ran horizontally away. I had started to plant in small holes to enable  establishment-watering to soak in. 

I then noticed in a late Spring following a very wet Winter that the shallow fall in level of the lawn - where the higher part of my garden gently slopes down - looked rather brown. An inspection hole revealed completely dehydrated soil. I recalled a former client in York who had had exactly the same problem. 

Soil hydrophobia is when fine particles of silt or sand refuse to admit water between their dry surfaces. Depending where it occurs it might be mild repulsion overcome by steady rain or in severe circumstances it needs  incorporation of bulky organic matter and dare I say loosening by cultivation to let in water! (This was to be a post in my ‘why gardeners dig’ series but I do not want to give gardeners too many excuses to dig, they invent enough for themselves!). I mentioned  adding organic matter but if this is also bone dry ‘from the bag’ it can be hydrophobic too. 

I checked on the net before writing this post and noticed people reporting hydrophobia on clay. I think they are probably wrong and they merely have compaction! When I water my none dug, beautifully structured, clay soil in my Bolton Percy garden water instantly soaks in. Pure joy.

Living with hydrophobic soil

I do not want to suggest I have a serious problem, more of a minor inconvenience to be overcome. Three quarters of my garden is low lying, receives ample drainage water from higher ground and the natural sub irrigation from my ‘perched’ and active water table ensures that even in Summer it does not become seriously dry. 

As long as I avoid small areas of elevated soil in the upper parts of the garden everything is fine. In this part of my garden established shrubs and perennials have deep roots and have followed the water table down. My trees grow particularly well. In Summer the ground water is perhaps six foot down.

The  metre wide slope on a small section of the lawn required special attention. I stripped away what pretended to be turf to reveal two foot of dust! It certainly took some wetting by repeatedly filling my holes with water and ‘working it in’ with my small border spade. As it started to wet up I added ‘water absorbent gel’ and crushed bark to ensure the problem would not reoccur. I re-sowed the surface with a fescue/bent fine grass mixture.

A grass path on the same slope was even worse. It gave Brenda a fine excuse to lay a lovely stone path. Her very successful avoidance ruse.

The slope on my lawn and Brenda’s fine path

Much of my upper garden is well mulched with bark and gravel and most surfaces therefore do not have the opportunity to become hydrophobically dry. The garden is rich in organic matter and stays moist. I never had a problem in my vegetable garden anyway, but now that I regularly spread my own lumpy biochar I do not even need to plant in holes!  I do find that my ferns do best where I have buried newspaper!

By ferns grow their very best in tubs of my sandy soil.

My sandy soil creates an unusual opportunity.

As mentioned earlier, when wet, my soil holds a lot of water and yet is well aerated. If used in tubs and containers and even pots and seed trays it does wet up as water soaks through.The water can go no where else as it is retained by the rim!  Unlike peat based composts  - which are hydrophobic when dry and making matters worse, shrink - water does not run through my sandy soil until it is at full moisture holding capacity. My soil in containers holds as much water as most regular seed and potting composts.

I have discussed this theme before in ‘Breaking the Rules’ where I tentatively suggested that skilled gardeners can use soil in large tubs and planters rather than compost. I plan to be bolder in a future post soon

Thank you Chiltern Seeds

Whenever gardeners have asked me where to get seed of unusual  or rare plants I have recommended Chilterns. Somehow the address, Bortree Stile, Cumbria, seems to stick in my mind and over the years I have enriched my garden with their seeds. I receive a treasure chest in the shape of their unusual long narrow catalogue every year. I must never have been a viable customer. I am not a big spender and my small annual order  - I am always tempted - will scarcely have enriched them. People say there is no such thing as bad publicity so here is my own attempt to promote them as a ‘thank you’ for years of pleasure and many fine plants.

Seed will never be the only way to furnish a garden, especially with perennial plants. There are far too many pitfalls. Cultivars of herbaceous perennials do not usually come true, some seed takes a long time to germinate and  even though of high quality and fresh sometimes fails to germinate at all. Some plants  such as trees and shrubs take many years before they mature. 

These woody plants can only be grown from seed

Despite my provisos there are thousands of fine plants that can easily and rapidly be raised from seed without needing any special knowledge or equipment. Some plants can only be raised from seed. Many plants are best raised from seed. Seed is arguably the most pleasurable method of propagation.

Mainly annuals

Mainly perennials

I don’t expect your own seed order will be the same as the plants I mention today. The plants I highlight are really reminiscences of my own gardening pleasures past and a few are extra delights anticipated this year. If you order their fascinating catalogue or go to their excellent website you will quickly alight on plants that take your fancy. Perhaps you will not be as frugal as me. Plant descriptions and tips in Chiltern’s catalogue are detailed, anecdotal, delightful and amusingly written. Sometimes they are brutally honest. I love their prose.

Tales of seed raised plants.

All plants mentioned are in Chilterns catalogue.

Nicotiana sylvestris.  This highly scented half hardy annual spontaneously returns every year. It pops up in May in my glasshouse as a volunteer in recycled soil, in June in my borders and even in my vegetable garden. It is wonderful for gaps.

Ecballium elaterium. The squirting cucumber. This insignificant, inelegant, inedible plant occasionally reappears as a tolerated weed. An eminent former colleague, a keen botanist stooped down to examine it. Right on cue, the squirting squirter shot him.

Smyrnium, Alexanders. I bought this one for it’s umbelliferous green flowers. We subsequently walked in East Anglia.It lined every farm field as a weed.

Verbena bonariensis. A posh lady client had eight herbaceous borders. She was very proud how they were generously suffused with this magnificent plant. She asked her new gardener to cut them back in November. He thought he would do better than that and yanked them all out!

White rosebay willow herb. Flower arranger  and Chelsea Gold medal holder Jackie Barber hired me to spray out the weeds in her herbaceous borders. I carefully sprayed her precious, not yet flowering, white willow herbs with glyphosate. She continued to employ me for another ten years and we are now very dear friends. (Sorry, it’s not in the catalogue but I could not resist the story).

Variegated honesty. When I started in Bolton Percy cemetery I generously scattered seed over ivy I had mown flush to the ground. The bold stand of flowers were outstanding on my very first Open Day. It has been with me ever since. Cultural note. If it germinates in Summer when it is warm, it is green;  if it germinates when it is cold it is variegated. Do not throw the green ones out, they will be your very best intensely variegated plants when they flower the  following Spring.

Cyclamen persicum - wild form. I shall be tempted this year to try this parent of the florist cyclamen as a cold greenhouse plant.

Chrysanthemum segetum. Corn marigold, I won’t be buying this! The field next door is full of it. I love it so much I have posted about it twice!

Dodecatheon. Shooting stars. Wonderful late March flowers for moist areas. I save seed every year to increase my stock. I have hundreds.

Sorry the white one is not in the catalogue.

Polygonum orientale. Kiss me over the garden gate. This magnificent six foot high annual germinates from self sown seed in late May, but only sparsely. I have lost it yet again and am delighted to be able to buy some more from Chilterns. If you are feeling naughty you can start a rumour that you have Japanese knotweed! You won’t have, it’s much nicer and of course it is annual!

Briza maxima. It has magnificent seed heads and self seeds itself in bold clumps in Worsbrough cemetery. The locals regard it as just another of my weeds.

Miriabilis jalopaa. Marvel of Peru. I sowed it last year in my unheated greenhouse in early April. Subsequently in my borders it made strong free standing un-staked multi-coloured plants. I have saved thousands of seed for this year. Sorry Mr Chiltern, I won't need to buy any more.

Silybum marianum. Askham Bryan students used to have lessons on Saturday morning. Not very popular to students or staff! I was taking the easy option, a walk round the grounds. A friendly but rather overconfident student sensed my discomfort as I hesitated over naming a self sown plant. I paused, looked him in the eye and triumphantly declared “its called silly bum”

Dactylorhyza. New self sown orchids sometimes appear in my garden in the most curious of places - cracks in the stone path and in the lawn. Chilterns are honest enough to tell you that your chances of getting it to grow from a seed packet are a cat’s chance in hell. They do provide a very generous packet at a relatively low price. It’s like giving a challenge!

Galtonia. This tall beautiful elegant bulb is magnificent in July. My long gone, much loved colleague, Jim Hingston called it one of the great plants of the world. It’s jolly nice Jim, but I could never understand why.

Dicentra. As holder of the national collection, I can inform you that D. scandens, D.macrocapnos, D. spectabilis  and D.eximia come true from seed.  Dicentra cultivars do not.

Eucomis, pineapple plant. Twelve years ago I sowed in my greenhouse a mixed packet of  eucomis seed. Three germinated and all proved to be distinct forms. They flowered after three years and I have now increased them by dividing on numerous occasions.

Peter Williams says thank you too!

Last week his lapageria in his frost free greenhouse flowered for the first time. Peter says he feels like a dog with two tails. Four years ago the beautifully packed seed came from Chilterns.

My seed order last year

Can you use fertilizer in Winter?

Garden myths discussed. You should not use fertilizers in Winter

I agonised before writing this post. In the first place is it a myth? Are there any gardeners who really believe you cannot use fertilizers in Winter? 

I seem to remember when I learned how to garden, vague notions of Winter fertilizer application causing soft unhealthy growth. I recall in the sort of gardening articles I only half read, warnings to put my fertilizers and liquid feeds away for the Winter. I think this advice might  be appropriate to those gardeners who should also put them away for the Summer as well!

I found myself thinking whether unhealthy soft growth is promoted by Winter nutrition. When plants at any time are given excessive nitrogen in the absence of other nutrients you do get extra vegetative green growth. This is not inconsequential and sometimes such growth is more prone to pest and disease. But is this problem more likely to occur in Winter? To what extent is growth promoted by nutrients at all when conditions are cold?

I think there is confusion with the  soft unhealthy growth encouraged by the use of too much heat in Winter. Inexperienced gardeners do not seem to realise that Winter light is often insufficient for many plants to healthily grow. I despair when I see five pound notes being burned heating greenhouses in January to enable excessively early sowings of  plants for later in the year. Don’t people realise that nature  makes a much better fist of heating? Sunshine comes in a neat little package, heat to make plants grow faster and light to make the sugars that are the ‘building bricks’ of healthy growth. It is no use whatsoever and positively harmful having too warm a greenhouse on a sunless January day.

Circumstances where Winter use of fertilizer is inappropriate

It would be foolish to apply fertilizer to un-cropped fallow land in mid Winter. Most fertilizers contain nitrogen in soluble form which will be wasted when leached out by winter rains and melting snow! On sandy soils that tend to be low in nutrient-absorbing organic matter, magnesium and potassium might be washed away too. This is less true of clay soils, which other than nitrogen, hold onto nutrients against leaching extremely well.

I define fertilizers as concentrated sources of nutrients and draw a distinction with bulky manures and composts where much of the nitrogen is part of the fabric of the organic matter itself. Soluble nitrate will be beneficially released from manures when the bacteria get active in Spring.  However, even manures and garden compost  also contain dissolved soluble nitrate in Autumn and I mischievously suggest that this will be subject to Winter leaching too.

Apart from wasting resources, fertilizer application to bare soil in Winter is irresponsible with regard to pollution. This is a danger when farmers fertilize large tracts of land in late Winter. We gardeners in comparison are very small beer.

Miscellaneous plants inside for the winter

Now in January my unheated greenhouse is packed with overwintering tender outdoor plants. Some are deeply plunged in the soil. Others are free standing in pots. Most - but not all - are dry. My desert cacti on the bench will not be watered at all until March. On a cold night it will freeze. None of these plants need fertilizer

Unfortunately my front porch is north facing. 

In my double glazed front door porch I have a small wall heater  with its thermostat set very low and the porch is barely frost free.Very tender plants such as my pelargoniums overwinter there. For the next two months there is very poor natural light and I do not want them to grow. They do not need feeding

When Winter fertilization might be good practice

I will mention a couple of less obvious fertilizer uses first. Lime is a fertilizer that provides calcium and in some cases magnesium. Its prime function is to elevate pH. It is normal practice to apply it in Autumn so that fairly insoluble calcium has time throughout the Winter to wash into the soil.

Iron sulphate is a fertilizer as well as a moss killer on lawns. It is a valuable source of iron and sulphur. Iron sulphate is used at all times of the year. I  last moss-killed my lawn on December 20th. The iron and sulphur may or may not benefit the grass straight away, but will certainly be still there when the grass starts to grow. If your lawn is more moss than grass, do not heed my advice - it will be black for a long time in a cold December and January before new grass replaces the moss.

On some occasions gardeners will be potting or sowing new plants in Winter. It will sometimes be wise to use a weaker compost than in Summer. Whatever your choice the growing medium will of necessity usually contain fertilizer. I find it interesting that sometimes it is a marginal and yet a fairly inconsequential decision whether to use John Innes 1 or John Innes 2 and yet the latter is twice as strong!

Plants such as my outdoor large tubs of Spring bulbs are making strong roots right through the Winter. Daffodils start root growth as early as September. It seems logical that they require Winter nutrition.  If I have neglected to fertilize my pots in Autumn as I ought to, I have no reservations about top dressing them with fertilizer in Winter. I have stated before that in fertile soil there is no need to fertilize bulbs naturalised in the ground at all. It might be worth mentioning that fertilizing bulbs in pots will have only a small beneficial effect on flowering next Spring, the value of feeding is strong bulbs for the following year.

Dicentra cucullaria

I have written before about pots of Dicentra cucullaria in my collection. These will be standing outside through the Winter and their soil nutrients will be depleted by rain. The pots will contain actively developing roots in early Winter and the plants will have completed their life cycle and go dormant by early May. In my opinion the best time for me to top dress the pots with my Yara Mila compound fertilizer is in December or January.

The principle I want to promote is that if plants are naturally making growth they will require nutrients to grow well.

I divided and planted Corydalis flexuosa on December10th. The second picture was taken three weeks later. By early March (if our current very mild winter continues) the pot will be a solid mass of gentian blue flowers. The strong winter growth needs nutrients.

Most perennial plants in the garden will be starting to make active root growth by late February - and some much earlier. Plants require nutrients for healthy strong Spring top-growth. I would expect to fertilize my blackcurrants, asparagus and rhubarb by early March. 

Those of you who are not regular readers of my blog might be imagining by now that I am a heavy user of fertilizer. I write elsewhere about gardening with no fertilizer at all. My comments in this piece are about the timing of applications. With a well managed soil in the majority of cases most established plants in the ground have sufficient nutrients without using any fertilizer at all. This post is not saying that you must use fertilizer. Just that you can.

Part of my cold greenhouse serves to grow alpines and the pots are variously in the greenhouse or standing outside. I also have tubs of Daphne mezeurium and Ribes  laurifolius which burst into beautiful growth in late January. I lightly top dress at that time.

The very fact that soil soluble nitrate is naturally low in Winter, means that  plants may not have enough of this nutrient. Some vegetable growers give their spring-greens nitrogen fertilizer in late Winter. Personally I am not a fan of single nutrient fertilizer but in some years do make an early application of my general NPK.

Just before Christmas

Our warm conservatory has acquired a solid new roof this year and the vertical east facing glass side has been raised. We eat all our meals, entertain, and generally live in this room. It is also packed with vegetation! The low Winter sun streams into this room. Most of the house plants are actively growing. Some like the epiphyllums, Christmas cacti and hippaestrums make more growth now than in summer. I posted a picture last month of my burgeoning bougainvillea - admittedly  about to go semi dormant January to March. Brenda’s ten year old calamondin orange will be heavy with oranges for another four months and very shortly will also carry flowers. We can count fifteen spikes on our orchids, three were in full flower for Christmas. Clivias which looked so tired when brought inside in early November have made vigorous green growth and now will be flowering for a three month period. All these plants need feeding in Winter.

What about the lawn? Notes for nerds

I do not wish to encourage you to fertilize your lawn in Winter, there are too many potential pitfalls. Never-the-less I would point out that most of those beautiful green pitches seen on Match of the Day receive Winter nutrition. I remember when our college hockey field looked very sparse in January and our turf lecturer arranged for a light application of a high nitrogen general fertilizer. With very good effect.

Perhaps emboldened by my own careless talk, soil scientist Peter Williams last month applied a light application of a general fertilizer to his lawn. Peter does not use iron sulphate as a moss killer and his philosophy is that if the grass grows well there is no need. His lovely lawn in Winter has a golden sheen due to moss. You can have too much of a good thing and his grass growth was weak. (Grass does grow in Winter on warmer sunny days. In the UK we even sometimes need to mow).

He applied a very low rate of even balance NPK at five gram per square metre. He is delighted with the new grass growth. He is considering applying a little more! I have provocatively asked him, bearing in mind that it is nitrogen in which his grass is deficient, why he does not go the whole hog and try a very light dressing of 20:10:10!

Peter is very pleased how his grass has grown after Winter fertilizer

On hearing of Peter’s ‘trial’ I rushed out and applied 30gram of Yaramila to a square meter of a pale patch of my lawn (marked by the plastic labels). 

Update June 2015

In keeping with blogging and trying things new I applied my YaraMila general fertiliser to my asparagus in early February this year. I have never had such superb fat asparagus spears! We can't keep up with them.

Related posts

My Yaramila compound fertilizer

Choosing fertilizer

Ordinary general fertilizer for lawns

London Open Squares Garden 14th-15th June 2014: Amsterdam Open Gardens 20th-22nd June 2014

Travel blog. Gardeners’ Paradise

If you are like me, it takes a lot to drag you away from your garden. To prize me away there are two significant criteria; to visit other gardens and not be away too long!  I wrote last July about our first visit to London Open Squares gardens. This year we are going again. Our cheap Waterloo Travel Lodge is already booked, my  OAP train pass is about to be renewed and R.Broom’s bus pass  - my writing is somewhat  illegible  - is at the ready. I hope you never see my bus pass, I look like a criminal!

We have been to Amsterdam Open Gardens three times in the last eight years. Each time with different friends and not always gardeners. The beautiful classical Old Amsterdam buildings you pass through to enter the gardens and the associated Dutch culture are a delight in themselves  and the thirty-odd gardens are a horticultural feast. An Open ticket for all of the Dutch gardens is only 15 euro. The ticket gives directions, cheerful volunteers mark your tickets as your record of achievement and most important all gardens are in a navigable area. You walk from garden to garden. We sometimes take a canal boat to a distant garden and wend our way back via gardens to our hotel in the evening.

Our own personal Dutch formula Is to sleep overnight on Hull Ferries, enjoying  the good food and wine. We are bused from Rotterdam to Amsterdam, take a taxi to the Eden Hotel where we stay two nights. That’s four nights away and three days feasting on gardens. Back home Monday morning. No need to ask Peter Williams to do any watering!

Unfortunately our visits to Amsterdam were before I became infected with bloggery and when I never used a camera!

In my previous London Gardens post, most of the pictures were from my good friend Harry Kennedy. Here is a composition of a few of my own.

I wonder what you think of the London plane pruned in the french style. I love it in street scenes when I visit France but am not sure about London. As I have grown older, I have moved from derision to begrudging admiration!

Although the Open Gardens Scheme provides a unique annual opportunity to see many of London’s gardens, many of the gardens are open more frequently and some all the time. Brenda’s son Iain has a flat a stone’s throw from the Shard (if you have a very good arm). Formerly a run down area, it now has new  tall modern buildings springing up every time we go. Alongside modernity there are many fine old buildings. It’s not far to the site of the old debtors’ Marshalsea prison, a relic of  Dickens time. On our last stay in Iain’s flat we had a local walk round. It is quite fascinating how many small gardens are so close to the Shard.

The picture taken from Iain’s window is Old Hallows church. Its garden is horticulturally un-special but it is a splendid green oasis in the busy city and it hosts a very fine acacia. From the same window looking up to a high horizontal roofline of flats you can see the top of the Shard. At night it looks like a huge colourful dalek standing on the roof. Sorry but my camera let me down yet again.

I liked this approach to the growing and displaying  of dwarf plants. Some fine alpine collections now use this technique which perhaps has some of the cultural advantages of a raised bed.

Pictures on our stroll 

If Borough market is open it is well worth a visit. All human life is here. There is so much tradition, craftsmanship, colour, character and fine produce that as the subject matter for a blog there would be stories for years.

Link  to London

Link to Amsterdam

Link to my earlier post

Remembering myths

Garden myths listed

It is traditional at this time to look back over the previous year. Today I would like to review  the nine myths in my series through the life of this Blog. It gives me an opportunity to blatantly advertise my wares and in addition clarify a few points that were previously blurred. 

You might have noticed that many of my myths relate to the soil. No surprise there then, it is one of my former lecture topics. I do find in the popular gardening press that very little is written about the basic elements of soil management and when it is, it is frequently wrong. When I struggle to read some of my older posts it makes me realize why so little is written!

Gardening is a minefield of mythical magic. Some so-called ‘facts’ are totally wrong. Many more are half truths based on unverified personal experience, outdated techniques, wrong explanations of verified facts, simple recipes that have more exceptions  than actual cases and at other times just pure opinion and much imagination.

I started my series with ‘debunk’ in the title. I soon realised that not only did this sound rather arrogant it did not cover most cases of factual dispute. I now prefer to attempt to ‘discuss’. Early on I failed to put the topic of the myth in the title. It makes it easier to use my search box now that I do. Except that for a couple of months now my search box has failed to work at all!  What a headline it makes, Google fails to find! 

Fear not I have provided links to each of my myths. I have recently been reminded that new readers do not always appreciate that to go to an old post you just click on the coloured highlight!

nb the very small search box at the very top of the blog finds and takes you to old posts  - best if the search term is either a single word or a an exact phrase. The large box at the bottom does not work at all.

Another way to find old articles in blogs is to go to any search engine and insert the blog title followed by the subject. ‘Roger Brook myth’ will find all my relevant posts.

Whilst I am going on about blogging, I would like to point out that blog comments are much appreciated in ‘old posts’. Blog writers receive an e-mail for each new comment and will almost always respond. When I started blogging I thought stuff in the archive was like old magazines and never read. Nothing is further from the truth and as search engines find them, old posts take on a life of their own!

The blogs

My first myth about water on leaves acting as a lens and sunshine scorching leaves is fairly uncontroversial and clearly untrue. Even with this myth, leaf scorch is a common phenomenon and sunshine can be involved when it causes desiccation in conditions of severe dehydration in drought.

The folly of using tree paint was also straightforward. I remember a former employer who had wounds on the trees in his arboretum expensively painted in a horrible blue. Above a cut on a beech tree I remember the biggest bracket fungus I have ever seen.

The common confusion between a (harmful) wireworm and a (beneficial) orange/yellow centipede was merely a matter of report.

The myth that it is better to water in the evening is common gardening lore. It seems so obvious to give plants a drink at night when surfaces will remain wet. Counterintuitively  water on a wet surface does not sink in at night in some magical way. If you give so little water that increased evaporative loss in the day is significant you are not giving enough water.

I had a hard time with my assertion that ground cover plants do not conserve water. It seems so obvious that they do conserve water when leaves shade the ground! The crucial point fundamental to all irrigation practice is that the very same leaves transpire oodles of water that thirsty roots have sought out deep in the soil. Many gardeners overwater small plants, especially in containers, when they fail to recognise this simple fact.

Water conservation is in practice more complicated than this. Plants have wonderful adaptations to conserve water when subjected to drought. Conversely, and less well appreciated, the same plants have a wonderful facility to transpire at normal high rates when drought does not prevail! 

Cacti in Madeira botanic garden will also dehydrate the soil

I acknowledge  there will be some circumstances where ground cover is subjected to drought (drought that it has itself helped to create!) or starts to go dormant, that its leaves will start to act as a mulch.

There was some dispute about this post - which I welcome - in my comment column. I (inadvertently) failed to reveal an argument contrary to my case, On hilly sites ground-cover has a significant role in reducing run-off in heavy rain.

A more exotic fact that illustrates nature’s wonderful diversity is that some desert plants are capable of absorbing sea mists and exuding water into the soil.

Ground cover is beautiful, is horticulturally and ecologically beneficial but does not usually conserve water.

Gardeners are told to dig to aerate the soil. If there is any validity to this nonsense there has been something very wrong with their previous soil management!

The dust mulch theory is very plausible. Fortunately for someone like myself who believes excessive soil cultivation damages the soil, the dust mulch story is almost completely wrong.

Dust mulching is the idea that cultivating the soil surface reduces water loss. This must not be confused with the horticultural truth that when the soil surface is dry it starts to act as its own mulch and reduces water loss by evaporation to almost zero - only to continue when the soil  surface is re-wetted by rain or irrigation. In contrast, water loss by transpiration from the plant continues until roots fail to find water.

Leaving aside the fact that many gardeners overuse fertilizers (and some fail to use fertilizers when they would be extremely beneficial) this post challenged the notion, dear to the heart of vendors, that every plant needs its own special potion. In a different post I discussed whether a special fertilizer was needed for the lawn.

Not all myths arise from ancient tradition as illustrated by this modern meme about rhododendrons

Some items of misinformation are discussed in posts not in my myth series. Many gardeners fail to understand the terms texture and structure when describing a soil. My recent post on mistletoe mentioned four different myths associated with this plant!