Garden Myths: Number 10

Plants will go to a particular size and stop.

People often ask for plants to do things that are not realistic and the commonest one is for a plant that will grow to a particular size and stop. That is understandable but sadly some people in the horticultural industry will actually tell them a particular plant will do just that. Providing such action is wholly unprofessional and reprehensible.

All plants will grow at different rates throughout their life and ultimately there growth will slow down a lot, but this can be when they are centuries old. Clearly some plants will always outgrow others but their growth is strongly influenced by the conditions they are grown in. To take an extreme example take an oak tree in open parkland and grown as a bonsai.

Garden Myths: Number 9

Evergreens don’t lose their leaves.

It is an old misconception, older enough for me to be for warned by my amenity horticulture lecturer, that people think by choosing evergreen you will not have to clean up fallen leaves. The logic is easy to see; if the plant is evergreen it has leaves all the time so they don’t fall off. The error of this will quickly become painfully apparent the first time they weed under a holly bush! While evergreen don’t shed all their leaves on one go: they do still shed them, as can be seen if you look under any established evergreen tree or bush and what is more they tend to take longer to rot down than leaves of deciduous plants.

Garden Myths: Number 8

Waterfalls and streams need a mains water supply.

The first time, on discussing creating a garden pond, the customer carefully explained where the mains water supply was “as I would need it” I was taken aback; but it has happened now a number of times. The logic I presume is that as there is water running it must be from the mains. To clear up any confusion the water is circulated by an electric pump. Using the water mains wouldn’t work for a number of reasons. Tap water contains chemicals such as chlorine and fluorine which are added that could harm the plants and fish, if you’re constantly adding more and more water from the mains where will the excess go to, what is your water bill going to be, what happens as the water pressure goes up and down, what’s going to happen to the water pressure in the house and a domestic water supply does have sufficient water pressure or flow rate for all but the smallest water feature.

Garden Myths: Number 7

Cacti don’t need water.

Every plant needs water. The amount they need varies greatly with a pond plant at one extreme and a cactus at the other; but they all still need some water. The plants grouped together as cacti have evolved to survive with very little water and very infrequent rainfall but like all living things on earth they need and use water.

Garden Myths: Number 6

It’s a simple environmental choice.

The road to hell is paved with good intentions

The problem with the environment is its complicated; I mean REALLY complicated! Not just fiendish Sudoku complicated, more theoretical physics complicated. In the environment everything interacts with everything else, so the simplest change can have completely unforeseen results. Take a simple example: many years ago a group of botanists wanted to protect a colony of rare orchids and so they put up rabbit netting around the plants to stop grazing animals eating them. So far so good, it seemed to everyone a sensible course of action. Everyone except the orchids which quickly died out in the fenced off area. Fortunately they did continue to grow at the site but not in the fenced of areas but in the grazed ones. The orchids relied on the grazing animals to keep the competing grasses down so they could flourish. Scenarios like this keep reoccurring time and again when people try to make changes to help the environment. The problem is that environmental campaigners keep making over simplistic claims about the needs of the environment; when the truth is far more complex.

The problem with the environment is its complicated; I mean REALLY complicated! Not just fiendish Sudoku complicated, more theoretical physics complicated. In the environment everything interacts with everything else, so the simplest change can have completely unforeseen results. Take a simple example: many years ago a group of botanists wanted to protect a colony of rare orchids and so they put up rabbit netting around the plants to stop grazing animals eating them. So far so good, it seemed to everyone a sensible course of action. Everyone except the orchids which quickly died out in the fenced off area. Fortunately they did continue to grow at the site but not in the fenced of areas but in the grazed ones. The orchids relied on the grazing animals to keep the competing grasses down so they could flourish. Scenarios like this keep reoccurring time and again when people try to make changes to help the environment. The problem is that environmental campaigners keep making over simplistic claims about the needs of the environment; when the truth is far more complex.

Garden Myths: Number 5

Slugs and snails can be kept off Hostas by raising them high up or setting them in gravel.

Hostas are a versatile and attractive genus of garden plants; used and loved by gardeners. Unfortunately the large succulent leaves that make them so attractive are also irresistible to slugs and snails. This has led to an all-out war between gardeners and gastropod, with peace loving elderly spinsters turned into pathological nocturnal hunters. In an attempt to keep the Hostas safe many ploys have been tried, including raising them off the ground. It doesn’t work, I’ve seen snails more than 2 metres up vertical brick walls. Sadly gravel is no more effective and so far the only reliable way I have found is regular use of chemicals.

Dicksonia antarctica

OLYMPUS DIGITAL CAMERAAs one of the most popular examples of this fascinating and fashionable group of plants, it is seen more and more available for sale. Appearing like a fern on top of a short trunk its slow rate of growth is reflected in its relatively high price. There is a lot of confusion over its hardiness with some saying it is only hardy in the mildest areas of the UK while others, including Kew, say its foliage is hardy down to -2°C but the plant itself is hardy down to -10°C. Part of this may be expectation as it is only found in the tropical regions of the southern hemisphere, but may also reflect the location a particular plant has been collected from as it is found at up to 1000m above sea level where plants would be expected to be more cold tolerant. With that in mind, and considering the cost of the plants it may be as well to adopt a cautious approach as frost below -10°C are not unknown in most parts of the UK and provide some frost protection. This is commonly achieved by wrapping the plants in horticultural fleece or straw secured with chicken wire.

Dicksonia antarctica

Dicksonia antarctica

Dicksonia Antarctica Labill. Thrives in cool damp situations: given time and the right conditions it can achieve a 3 metre trunk and 2.5 metre long fronds. To do well it needs plenty of water and given enough water it is quite tolerant of exposure to sun. As you might expect from its natural habitat it does best in a humus rich acid loam but it is quite capable of growing in most soils, even poorly drained ones. There slow rate of grow makes them very suitable a pot plants, which allows them to be moved indoors in cold weather, but they do resent being pot bound. The strange structure of the trunks means the top of a tree fern can be cut off and will regrow if being planted; but the lower potion will not as it is composed of dead material.

The extant species of tree ferns are a remnant of a far greater group which helped lay

Dicksonia antarctica trunk cross section

Dicksonia antarctica trunk cross section

down the coal seams mined today. They do not form a taxonomic group as such and the term only refers to any tree with a wood like trunk raising the fronds off the ground. In UK gardens Dicksonia Antarctica Labill.is the species most commonly found and as originally described by Jacques J.H. de Labillardière. M. Labillardière published his description in the second volume of his to volume Novae Hollandiae Plantarum Specimen, which was the first flora published of Australia (or New Holland as it was then known). The journey from Australia to the floras publication in 1806 was anything but straight forward. Labillardière was a naturalist attached to the expedition the French sent out to find what had happened to the expedition lead by Jean-François de Galaup, comte de Lapérouse. They failed to find the lost expedition but did explore parts of Australia, New Zealand and surrounding islands. While they were away The French Revolutionary wars were causing upheaval in Europe and on reaching Java the expeditions scientific collections were seized by the British. It was only by appealing through influential British contacts that he was able to secure their return and so publish their descriptions.

References:

Dicksonia trunk showing aboriginal carving

Dicksonia trunk showing aboriginal carving

http://www.kew.org/plants-fungi/Dicksonia-antarctica.htm

Encyclopaedia of Ferns by David L. Jones

Hardy Garden Plants (3rd Edition) by Graham Stuart Thomas

http://www.forestferns.co.uk/

‘The International Plant Names Index (2012). Published on the Internet http://www.ipni.org [accessed 24 June 2013]

Novae Hollandiae Plantarum Specimen by Jacques J.H. de Labillardière

Garden Myths: Number 4

You can get grass to grow well in the shade.

No you can’t. Grass will put up with a lot; how any plants will put up with being regularly cut down and walked all over? Like everything it has its limits and it is never happy in shade, needing full sun to do well. What about shade “tolerant” grass seed varieties you say? Yes, some grass is more tolerant of shade than others; but that’s not the same as happy in shade. If the shade is slight these are probably a good idea, but once you start to get under trees and the like you cannot expect them to be any better than any other grass.

Garden Myths: Number 3

Garden ponds need a filter.

Properly designed and planted a garden pond does not need a filter. Long ago when I was a child we had a garden pond, along with many other people of course, but no one had a filter on them. This was for a good reason; they didn’t exist for garden ponds. What changed things was when people in this country discovered the hobby of keeping Koi fish. These fish are large, colourful, expensive thugs that dig up any plants growing in the pond. This meant people wanted ponds with just the fish in them but the fish could not survive in these conditions so Koi keepers invented the pond filter. This allowed pond water to be artificially kept very clear so people quickly realised it was easier to fit one of these to the pond to get clear water without the fuss of making sure the pond was properly planted up.

Garden Myths: Number 2

Parsley seed must be soaked before you sow it.

Some plants seem to attract myth and superstition and parsley is one. The truth is parsley is slow to germinate and gardeners can be impatient, so people have looked to ways to speed things up. To this end it is often said you need to soak parsley seed to get it to germinate; however it will germinate without any soaking. What if any difference soaking makes how quickly it germinate I do not know, but have you ever tried to thinly sow wet seeds? You can’t, they just form a wet clump.

Personally, I just scatter the seed over a patch of fine earth and water it just as if were grass seed and wait. In a few weeks it starts to germinate and once the first true leaves appear you can easily spot what parsley and what isn’t so you can weed and thin as needed.