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Gardening Myths and Misconceptions

UIT Cambridge Ltd

A WEB OF MYTHS AND MISCONCEPTIONS

Gardening myths link together and support each other, establishing a network of jobs that one is supposed to do, and a number of things that one is not supposed to do. Therefore I find that not doing one supposedly necessary job frees me up from needing to do another. This book, then, seeks to unravel a long trail of gardening mysteries and complexities, revealing an underlying simplicity that makes our tasks quicker and less numerous.

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You may wonder why some or even much of the advice in this book appears to contradict what you have previously heard – and so do I! I think a lot of confusions arise from the widespread application of good knowledge in the wrong place, and there are several reasons why this has happened, and continues to happen. Advice may have been valid once and then become inappropriate in changed circumstances; or is based on a translation of inappropriate methods from farming to gardening; or has simply mutated through language, with words being misunderstood.

SOME WELL-ROOTED MYTHS

To give you an idea of how myths grow, here are just three examples of gardening methods that were or are appropriate in their original time or context. They need understanding in that context to see whether they are relevant now or in different settings.

* In large gardens, owned by wealthy elites, there was spare labour in winter for jobs such as washing pots (to restrict the spread of disease) and digging soil (for all the commonly cited reasons), with no need to ask how necessary these jobs are.

* Many mixed farms, at least until the advent of chemical fertilizers and weedkillers, practised an average four-year rotation of crops – which makes sense in large fields where the same plants are grown in large blocks and animals are available to graze pasture. However, in gardens, especially small gardens and also where double-cropping is practised in the same year, a four-year rotation is often impractical and restricts the output of produce.

* The use of undecomposed mulches, while good for protecting the soil surface in dry climates, causes problems in damp climates, where there is less need to conserve moisture at all times, because the mulches provide habitat for slugs.

REALLY? WHY IS THAT SO?

Many questions I am asked about tips for better gardening start with something along the lines of 'My allotment neighbour / favourite TV presenter said ...'; 'My mother/uncle advised ...'; 'I heard/read that ...' Often the advice sounds highly doubtful to me, but the listener trusts his or her source and does not have enough experience to perceive the unspoken assumptions, hidden misunderstandings and occasional nonsense. If you receive information in this way, and are unsure of its truth, I suggest you reply with a question of your own: 'Why is that so?'

Much freely given advice is not wrong in itself, just inapplicable in all situations. For example: that you 'must have a four-year rotation', 'must water in the evening', 'must run your rows north–south', 'must stake all newly planted trees' and 'must make a trench for growing climbing beans'. All can be answered with: 'Have you ever tried not doing any of these things to check how necessary they are?' I know from experience that none of these pieces of advice are rules that have to be followed.

The important thing is to understand why the supposedly necessary task is recommended, so that you are empowered to make your own decision in your particular garden – and thereby be freed from the clutches of rules and recommendations of variable worth. The following examples show how commonly held but inaccurate beliefs are to be found in almost every aspect of gardening.

FEEDING MYTHS

In the last 150 years, new fertilizers made from water-soluble nutrients have completely changed the way that plants are fed. But this has happened without all the understanding necessary to accompany such a radical change of method.

For example, some farmers and gardeners still use the traditional word 'manure', originally a description of nutrient-rich excrements and bedding, as a term for synthetic, water-soluble fertilizers.

Because these fertilizers make soil more acidic over time, this has led, by association with the word 'manure', to a belief that animal manures make soil more acidic when used regularly. Many gardeners are confused by this, as I know from frequently being asked to clarify this matter!

More confusion arises when unspoken assumptions about feeding plants are applied to these two fundamentally different approaches. Most of the nutrients in synthetic fertilizers are water-soluble, while the nutrients in composts and composted manures are insoluble in water and become available to plants when temperature and soil biology combine to allow access by growing roots. In practical terms, this means that compost feeds the soil rather than the plants and that you can spread it in autumn, unlike synthetic fertilizer, which would leach away in winter rains. Even some organic gardeners do not appreciate this. See Chapter 7 for more on feeding.

MYTHS AND MISUNDERSTANDINGS ABOUT EQUIPMENT

It is easy to spend money, then frustrating sometimes to discover a simpler approach for less expense. Save your money until you're sure of what you really need for your garden! For example, when growing vegetables we are often encouraged to invest in raised beds with wooden sides. These have some advantages, but check the evidence described on page 38 before you spend the money. Composting can be made expensive too, as I know from spending over £300 on an 'easy turn' tumbler. Well, it was easy to turn, but did not make good compost in the advertised time, even when I was precise about the ingredients added, which is actually quite difficult in gardening. So I continue to make lovely, slow compost in slightly ramshackle, home-made heaps, which cost only my time to assemble and give me more satisfaction. For general gardening tools, I suggest borrowing or buying a friend's or second-hand ones before investing too much, because we all have different ways of using spades, hoes, trowels and secateurs; no tools are 'best' – only you can decide, based on your own way of using them.

MYTHS ABOUT DE-LEAFING

There are common misconceptions about plant growth, such as the oft-quoted maxim that stripping tomatoes of their leaves in late summer helps fruit to ripen. Some extra colour is the most you can achieve by doing this, whereas true ripening is part of the growing process, so requires photosynthesis, not just sun hitting the fruit – and ripening fruits need the sugars and nutrients from many (not all) leaves to help them develop the best texture, size and flavour. I suggest removing only the old, lower leaves, which also reduces the risk of blight by increasing the passage of dry air at surface level (more on this on page 41).

It is the same for vines, whose leaves are photosynthesizing in late summer to make sucrose for ripening grapes. They can be partially de-leafed to increase grape colour and above all to improve plant health, by increasing air circulation around the grapes to reduce powdery mildew and rotting of dense bunches. But many leaves are left on vines at this time, to enhance grape sugars and flavours.

There is also a recommendation to remove the fading lower leaves of celeriac, when roots are swelling in late summer and autumn. This certainly makes the plants look more attractive, but when I experimented by removing lower leaves on just one side of a celeriac bed from August onwards, the resulting roots were 20 per cent smaller by November than the untouched celeriac on the bed's other side.

MYTHS ABOUT LOOSE SOIL

One of the biggest misunderstandings within gardening lore is a belief in the value of loosening soil before sowing and planting, and sometimes around existing plants in herbaceous borders. I don't wish to deprive those who enjoy digging and tilling of their pleasure, but seek to reassure those who have been told that loosening soil is necessary, yet don't want to or are unable to. Apart from planting trees and digging out woody roots and parsnips, I disturb soil very little and have found that growth is abundant, with fewer weeds, less need to water and often less slug damage.

Another benefit of this approach is that undisturbed soil is less sticky. In one year of endless rain throughout summer and autumn, I was able to carry on picking, planting and clearing in almost any weather, on an acre of clay soil. While fellow growers were mired in mud, my land was full of new plantings, with fewer weeds and less slug damage than is 'normal' in such weather.

MYTHS ABOUT SLUGS

Except in extreme weather, slugs do not randomly eat any old (or young) plant, because their role is to recycle decaying and weak leaves. Growing plants in well-fed soil and keeping slug habitat to a minimum reduces damage, although vigilance is always required.

I have found in my dig/no-dig experiment that there is less slug damage in the undug beds than in the dug beds growing the same plants. There are probably the same number of slugs in each case, but the crucial point is that when plants are healthier, slugs eat less of them, and this is just one part of an interconnected sequence of cause and effect in untilled soil:

* Fewer weeds germinate because undisturbed soil has most of its weed seeds lying dormant at depth, away from the light, which would trigger their germination.

* Fewer weeds results in less habitat of their moist leaves for slugs to hide in by day and then eat by night.

* Compost on top has a rougher surface than dug soil of most types and especially silts and clays; slugs prefer soft soil for slithering over, and appear somewhat less active on surface compost.

All the examples in this chapter illustrate the interconnected nature of gardening practice, both for better and for worse. They show how understanding myths and being released from their tyranny can free up our time, enable better growth for our crops and make our gardening more creative.

SOWING AND PLANTING

Some well-known pieces of advice about raising plants, which may have been sensible in their original context, have turned into misleading myths. Seeds want to grow, and when sowings are timed to give them the correct temperature, you need worry less about having a perfect seedbed or clean seed trays.

'Vegetable seeds should be sown in spring.' Partly true

Gardeners worry, and are led to worry by those who have sown early, that seeds must all be in the ground at the first hint of spring. This is untrue, because for best results there are different times of sowing for different vegetables, from February to November. In fact, a great tip is to be patient in spring, since later sowings of heat-loving plants often catch up earlier ones. Be ready with different seed at all times, in order to keep the plot full and have harvests in every month. Here are some guideline dates for sowing vegetables outdoors:

* Early or late winter: broad beans.

* Early spring: peas, spinach, lettuce, parsnips, onions, early potatoes, calabrese and carrots.

* Mid-spring: maincrop potatoes, beetroot, leeks, autumn cabbage.

* Late spring: chard, Brussels sprouts, squashes, courgettes, French and runner beans, swedes.

* Early summer: cucumbers, carrots and beetroot for winter, kale, Savoy cabbage, lettuce for summer.

* Midsummer: chicory for radicchio, coriander, chervil, wild rocket.

* Late summer: salad rocket, oriental leaves, endive, spinach for winter, spring cabbage and onions.

* Early autumn: wide range of salad for winter leaves.

* Mid-autumn: garlic.

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'Pots and trays for seeds and plants must be clean and sterile.'Untrue

Washing and sterilizing containers is a long and unexciting job, so it is good that even the Royal Horticultural Society is now agreeing that it is not a necessary task after all. Perhaps historically it had become a habitual task in large gardens, where pot washing was something to keep spare labour occupied in winter months, and other gardeners then copied their supposed superiors. Common diseases of plant raising are avoidable with good practice and do not originate in the materials used.

For raising and growing vegetable plants, I never even brush or clean any of my trays and pots between uses, let alone sterilize them: over three decades they have produced up to a hundred batches of healthy plants, with trays being used three or four times a year, simply refilled with new compost for each sowing. The occasional diseases I have experienced are results of the weather and my mistakes – mainly damping off (leaves killed by fungi) in humid conditions when seedling leaves were too close together, watered too often or sowed too early.

'Plants grown under cover always need careful hardening off before planting in soil.' Partly true

'Hardening off' means keeping indoor-raised plants outside for a day or two before planting them in soil. Some hardening off is good; however, as with many statements that have become rules, this needs to be qualified, and there are cases where hardening off can be avoided to save time and speed up growth. I know this from successful plantings of lettuce, spinach, beetroot, onions, courgettes, peas and so forth, brought out of the greenhouse and put in the soil straight away. In spring, when the air is cold but the sun is bright, I use fleece to cover new plantings, so that although the plants' roots are briefly cooler than they were used to, their leaves are protected from wind, which is often more harmful than low temperatures.

Also, you need to know which plants are frost-hardy, because one often encounters advice such as 'cover broad beans, peas, sweet peas and garlic plants to keep frost off, or bring them back indoors at night'. Yet none of those plants are killed by frost – and nor are lettuce, spinach, brassicas or onions. Only cucurbits, tomatoes, summer beans and sweetcorn are killed by freezing, so wait until frosts are finished before planting them out.

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'Soil is best pre-warmed by covering before sowing and planting.' Untrue

I have tried this and noticed little difference – certainly not compared with the more important job of covering after sowing and planting, when growth is actually happening. Pre-warmed soil does not hold on to that extra heat for long, and plants benefit more from being protected once they are in place: not only having some extra warmth but also with less wind blowing their leaves.

Warmer soil in spring is something to strive for, and when I was member of a growers' cooperative in the 1980s, the other growers always commented on the earliness of my crops. This set me wondering whether untilled soil stays warmer for plant growth because there is better conductivity of warmth from deeper below ground. When soil has been tilled, a 'dividing line' is created between denser, homogeneous soil below and the looser, tilled soil above, making it harder for roots to access moisture at deeper levels, and this probably also interrupts the rise of warmth from below.

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'You cannot transplant root vegetables.' Untrue

Root vegetables can all be transplanted, but special care is needed with carrots and parsnips to preserve the main taproot in one piece before planting. This can be done either by planting them small or by using long 'plugs', such as toilet rolls or root-trainers. All other root vegetables transplant easily, especially when started off in modules to ensure reliable germination, minimal root disturbance and to bring the harvest forwards. For example, you can sow beetroot under cover in late winter for planting a month later under fleece, harvesting them before midsummer when their flavour is especially sweet and other vegetables are scarce.

To save space, time and compost, sow four seeds of beetroot, shallot or radish, or up to six seeds of onion, in the same module and plant them out as a clump, with the developing roots then swelling together and outwards in their clump. Sow two swede seeds in a module and thin to the strongest, for growing into one large root from a planting in early summer. The tiny seeds of celeriac are best sown in a seed tray for pricking into modules when seedlings have two leaves, then planted out before early summer.

'Certain other plants need to be sown direct.' Often untrue

Although similar to the previous myth, this one is more vague, but one sees advice such as 'coriander / Californian poppy / etc. are best sown direct because they do not like being transplanted'. Well, judging by how well they have grown for me after being transplanted, I take such statements with a pinch of salt. Often I transplant twice: pricking out from seed tray to module, followed by planting out into soil.

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Excerpted from Gardening Myths and Misconceptions by Charles Dowding. Copyright © 2014 UIT Cambridge Ltd.. Excerpted by permission of UIT Cambridge Ltd.
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