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Invasive and toxic plants

  • France
  • 15.2.2019


Most plants have varying degrees of toxicity, even those that are sometimes used in home-made remedies, pharmacology and homeopathy in infinitely small doses. It all depends on the part of the plant (root, stem, leaves, flowers, fruit/seeds) and its use (handling, ingestion, maintenance).

There are a large number of allergenic or poisonous plants, that are kept in the garden because they have beautiful flowers (jimsonweed, foxglove, spurge), because they bear decorative fruit (spindle tree) or because they are edible when cooked (parsnips).

And just because birds eat certain berries that doesn't mean that we humans can do the same: if birds swallow the whole fruit, they excrete the poisonous seeds about 20 minutes later and, therefore, consume only the sometimes non-toxic pulp (example: the yew; the seed is poisonous, but you can make jelly out of the red pulp), while children would consume the whole fruit with the seed that is poisonous for them.


Botanists and gardeners have always brought plants from elsewhere into their gardens that have acclimatised very well and like some wild plants that "invite themselves", they become "invasive". When a plant settles at the expense of a native plant, it becomes "invasive" and it is difficult, if not impossible, to eliminate it.


Sometimes plants are both poisonous AND invasive.

And then gardeners have to take precautions to avoid incidents. Identify the plant first and do not let the unknown plants grow in your beds or under small fruits.

If you discover the few common, simultaneously invasive and toxic ones described below in your garden: Do not throw them into the compost! Do not let them get seeds and sow again! Throw them away and put on gloves!

Very often their flowers are generous and their colours bright; they have original and decorative fruits; their flowers attract butterflies, bees and all kinds of insects, but also the attention of children (or even adults who think they know the plant) who may confuse them in nature or in the garden with small edible fruit. The list of intrusive/invasive plants, that are a little allergenic and of toxic plants that cause mild digestive disorders, including cramps, cardiovascular problems, coma and death, is long. In case of swallowing and if in doubt, do not hesitate to call the poison centre nearby.

Here are two wild plants that are best not used in the garden:

Solanum dulcamaraThe BITTERSWEET NIGHTSHADE 'Solanum dulcamara', also called bittersweet or liquorice of the witches. From the Solanaceae family such as potatoes and tomatoes, it is a wild hedge plant with woody stems that sometimes invites itself into your garden, clinging to the fence or to shrubs. Since the plant blooms for a very long time, we can see the whole evolution of the plant at the same time: Lots of small purple flowers, hanging grapes of oval, smooth and green berries and bright red berries when ripe, which become wrinkled at the end of the season.

As so often, the green berries are more poisonous than the ripe berries. With its multitude of berries, it is a plant that should not be allowed to reproduce in the garden.

Like the kermes berry and many berry plants, the bittersweet or red nightshade is endozoochorous: its seeds are distributed by birds after passing through their intestinal tract.

The fruits are rich in alkaloids and poisonous: abdominal pain, nausea, vomiting, cramps, diarrhoea. For a child, a few berries can cause cramps or even a coma.


Bryonia cretina ssp dioiaTHE BYRONY 'Bryonia cretina ssp dioia' - "Devil's turnip", "Snake" Perennial herbaceous plant from the pumpkin family, climbing plant, in gardens and towns, on fallow land, dioecious (female and male flowers on various plants). Its many stems, with very dark green leaves, grow up to six metres high and can hold on to very special tendrils, which initially seek hanging support by wrapping, and when they find it, the twists wind ten times in one direction and ten times in the other (an exception in nature), ensuring that the hanging power increases. Its root is a melon-sized tuber. Pretty small, greenish-white and hairy flowers precede clusters of smooth, spherical berries that are light red when ripe.

Very toxic poisonous plant: Gloves are essential to handle all parts of the plant, allergenic or toxic. Skin contact can cause dermatitis; berry ingestion causes vomiting, diarrhoea, delirium and cramps, convulsions, hypothermia and coma. Children can confuse ripe bryony berries with currants; the lethal dose is about ten fruits.


An invasive and toxic plant so decorative that there is a great temptation to keep it:

phytolacca americanaThe AMERICAN RICH, 'phytolacca americana' or 'American Grape' - also called 'cayenne spinach', 'varnished grass', 'dyer'. A perennial herbaceous plant of the Phytolaccaceae family, native to North America and introduced to France in the 1990s. They are perennials that can grow three to four meters high with long, thick but hollow stems, ranging from pink to purple; their long, semi-evergreens are pale green, and their clusters of bright white or pink flowers are followed by fleshy berries of bright green, which turn bright black-violet after maturity.

It is very productive, but at the same time obtrusive, invasive and toxic: its root rotates (like the carrot) and sinks very deeply; it needs spade and pickaxe to extract the impressive trunk. It spread throughout France and uprooting campaigns had to be organised (Fontainebleau and Landes forests) because it eliminated all plants except blackberry bushes and ferns in its surroundings.

The berries are toxic and fatal to humans (vomiting, hypothermia, cyanosis), the leaves are toxic to pets, even earthworms and snails.


A poisonous shrub that must not be placed in the garden:

Ricinus communisTHE CASTOR BEAN/CASTOR OIL PLANT 'Ricinus communis' - It is a beautiful shrub of tropical origin (Africa) of the Euphorbiaceae family, cultivated in hot countries to collect the oil. Here it is often used in the middle of a massif or isolated, because of its decorative aspect with its large green or purple palm leaves; its fruit in groups of prickly, raspberry-coloured spheres contain large, light-coloured seeds, marbled brown and red, which are newly sown again by themselves.

Decorative, but oh so poisonous! The whole plant is poisonous; it contains ricin, a poison 6,000 times more poisonous than cyanide and 12,000 times more poisonous than rattlesnake poison. Castor oil is not recommended for our gardens as it is toxic to hedgehogs, it even kills cats and dogs and 3 seeds are deadly to children. If you have to pull it out, put on gloves!

Fédération Nationale des Jardins Familiaux et Collectifs (French allotment garden federation)


  • France
  • 31.1.2019

Numerous manual or motorised tools transport earth, leaves, seeds, pollen, arthropods and plant exudates from the place where they were used to another. Many living antagonists of crops can be disseminated by these means. Most of the time this dissemination is without consequences because of the banal character of these antagonists. However, it is prudent to apply simple cleaning or disinfection measures to the different tools to prevent the spreading of bio-aggressors.

Take advantage of the winter break to make an inventory of the maintenance work to be done on your tools and at the same time carry out the cleaning of your garden shed.

1How to proceed?
Tools should be classified according to their category. This is more convenient and so you do not get confused with maintenance products and equipment.

Hand tools
Usually they are equipped with a handle that requires special attention. Already when buying them, it is wise to prefer solid and flexible sleeves in beech or ash wood. The wearing of the sleeves often occurs at the fasteners: tighten the screws or change them. Sometimes it is enough to soak the sleeves in water for one night, so that the wood swells and thus prevents the tool from moving. A careful washing will remove dry earth. Then a light sanding with sandpaper followed by a coating with paraffin or linseed oil will protect the wood. Some tool makers opt for synthetic sleeves. If these gain in strength they, however, facilitate the formation of blisters on your hands. This material does not absorb transpiration. For the spade, the fork, and all the tools used to work the ground, the cleaning of the metal part begins with a wire brush to evacuate the dry earth, followed by an application of draining oil or white vinegar. The material will thus be protected from rust.

Cutting tools
Such as tree-trimmers, shears or secateurs. The maintenance of the blades is done with rubbing alcohol, you shoot two birds with one arrow, you get rid of the resin of the blades and the alcohol plays a role of disinfection agent). The sharpening of the blades may be necessary. To restore the edges, it will be necessary to use a file. Don't forget to grease the axels and the spring with Vaseline or consistent fat.

Motor tools
Before you start maintenance, carefully read the instructions of your lawn movers or other trimmers. Basic precaution before any intervention: unplug the power tools and remove the spark plugs for the thermal equipment. Empty the engines, empty the tanks, grease the axels and sharpen the blades. Note: an excessively damaged blade reduces the performance of the machine. The knives of the plant grinders have to be regularly sharpened.

Pots, buckets and stakes
Start with an energetic brushing to remove all soil leftovers. Then pass with a sponge soaked in bleach (bactericidal) and rinse thoroughly. The wooden stakes are quickly damaged. Remove most of the earth by scrapping with a knife and immerse them in a container filled with a mixture of water and bleach. After drying, an application with a "bouillie bordelaise" (A fungicide prepared with a copper and chalk mixture) will complete the operation. You can also use rubbing alcohol for your metal stakes. Do not forget your seed boxes, the wheelbarrow and the planks you place between the rows. The wood is an excellent refuge for insect larvae.

The sprayer does not make an exception to the rule
Never store a sprayer containing a preparation residue: the preparation quickly loses its properties and it is likely to damage the device (corrosion, clogging). After each use, rinse with clear water and use a light pressure to clean the lance. The joints dry out: lubricate them occasionally with grease or vaseline.

The watering equipment
This equipment has to be placed, so that it cannot be affected by frost (pumps, programmers, ducts, pipes). The latter will be emptied from its contents and placed at height so that it empties itself.

2Last step: The storage
Finally, and so that your efforts will not be in vain, store your tools in a dry place. The ideal is to hang them on a wall (to evacuate the humidity) the metal part at height and taking care to place the sharp parts as much as possible facing the wall.

Tips, tricks and advice

- Here is an easy trick to sharpen and to protect a tool while cleaning it. Just fill a bucket of sand and add 500 ml of vegetable oil; mix well and place it at the entrance of the storage room. Every time you enter, immerse the tool in the mixture: the sand will sharpen and polish while removing rust.

- Jean-Paul, French gardener emeritus, recommends the grindstone to sharpen the secateurs. This enables you to make a beautiful cut that will heal quickly and prevent the installation of diseases. Disinfection with rubbing alcohol is required after each use.

- White vinegar, a very effective product to remove rust is above all very ecological.

- Protect your hands: push the tip of the tools into an old tennis ball. Insert the saw blade into a garden hose cut lengthwise.

- Before using electric devices outdoors, make sure that the grass is not wet, that the connections are in good condition, that the wire is not damaged and does not drag in a puddle of water.

- Cleaning of the gardening gloves: put on the gloves and rub your hands with water and a detergent, rinse; when they are dry put them in their place.

- Get rid of rags soaked in oil and gasoline; they could catch fire; bring them with the remains of pesticides, stored in a suitable and sealed container, to the waste service.

- A simple rule to be applied in the garden is to start the work in areas that are a priori not contaminated and finishing the task in the zone that is supposedly infected.

- Remove squatters (reds, mice) from your shed with traps (available in garden centres).

- Eliminate everything that is bulky around the shelter to restore its good looks.

Nest boxes

  • France
  • 14.12.2018

At the beginning of the year we were alerted by the results of a European study which noticed the very sharp decrease in the number of birds, especially of sparrows, around inhabited places. There are several reasons for this situation. On one hand, the disappearance of a large number of suitable nesting sites and, on the other hand, the reduction of the available prey volume, as a result of agricultural practices and the use of insecticides.

01On our allotment sites and on our plots, though modestly, we can act on both of these factors. First, by installing nest boxes, then, second, by making sure that, there is a well-stocked natural pantry all around.

Before setting up a nest box, you must choose a place that best guarantees the, safety both of the brood, and the parents who look after it. In our gardens there can be wild predators as, for example, beech martens or weasels. Above all, however, there are cats. It might be wild cats or cats with owners, filled bowls and soft cushions, but who, as soon as they leave the home of their master, go hunting. Recent studies show not only that this expedition is much longer than previously estimated, but also that the cats found were often not the ones expected.

So, watch out for anything that can be used as a footstool, hiding place or perch for cats.

For the same reasons a nest box must be very strongly and securely fixed. It must resist all weather conditions and possible unwanted solicitations, as for example, from magpies and crows in particular. The presence of a few bushy shrubs will allow the young birds to go to safety when they leave the nest for the first time.

For a nest box to function, it must comply with a certain number of constraints: it must be adapted to the nesting sites needed by those species of birds present on the site or for those you want to attract.

One of the most important elements is the diameter of the flight hole. For small birds (blue tit, crested tit, marsh tit, coal tit) and tree sparrow it should be 26 to 28 mm. For birds a little bit bigger, like the tit or the red tail white face, it should be 32 to 34 mm. The distance between the base of the flight hole and the bottom of the nest box must be at least 17 cm, so that the young birds remain out of the predators' reach.

Inside the nest box at least one of the boards must be sufficiently rough, so that the nestlings can cling to it to climb and leave the nest. Do not hesitate to "rework" it with a chisel if necessary.

Here are the dimensions of the different elements for a simple nest box, which can be cut from a board of 2 meters long, 180 mm wide and 20 mm thick:

02Roof: 180 x 220 mm
Base: 120 x 140 mm
Back: 120 x 270 mm
Front: 120 250 mm
Sides: 270 x 180 mm

To accommodate other species of birds, different types of nest boxes can be integrated during the construction of a garden shed. In the North of France, we still can find "sparrow pots" that work very well. That's all for the shelter. Let's now go to the table.

Herethe strict application of the allotment gardens rules established by the Fédération nationale des Jardins Familiaux et collectifs (French allotment garden federation) finds its full justification.

In order for young birds, as well as the gardener's children, to receive a healthy and sufficient diet, the use of any chemical product and insecticide must be permanently banned. These products are considered as being insectivores so you must leave them their prey at least during the feeding period of the young. They take extremely well care of them. It is rare for cabbage white butterfly caterpillars to fully develop in a garden with a busy nest box. And it is the same for many insects.

In addition, the mulching of crops and a few piles of decaying plants in the corner also bring prey in large number.

Remember to have a bowl with clean water near the nest box. If the bowl is large, always leave a bundle of wood that will serve as a perch and will prevent drowning.

New nest boxes must be installed in early winter. The existing nest boxes that have already been used, have to be cleaned and disinfected before they are put back into place at the same time in early winter...

If you want to get started with the installation of nesting boxes at a large-scale, it is absolutely necessary to get into contact with the bird protection league, which has up-to-date information and scientifically validated technical data.

Serge Ratié

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