The Wicked Garden 1: Poisonous Plants

A Garden Designer’s Guide To Poisonous Plants


There are dangers lurking in almost every garden, and even in the conservatory - dangers to humans, animals, birds and beneficial insects. They are also evident in the wider countryside, along hedgerows, in innocent-looking streams and in woodlands. One such danger is that of poisonous plants, many of which are far from obvious except to the expert. Those discussed in this blog are by no means exhaustive, but illustrate a range of concerns that should be foremost in the designer's mind. You need always to be sensitive to these dangers, whoever your clients may be and unquestionably if they have young children, or pets. Awareness is also in the interests of your own health and safety when designing and working with plants.

A surprisingly large percentage of plants are toxic or poisonous to handle, or to eat. The humble potato is poisonous raw and cooking will not eliminate the poisonous green parts, which should always be discarded. The milky sap of the beautiful euphorbias (spurge) will burn and blister skin and will despatch you to hospital if you should get it into your eyes. Always make sure that your clients know they should wash their hands and those of their children, after handling plants or playing in the garden.


If ' mushrooms' appear in the lawn they are probably not the edible fungus that is tray packed in the supermarket. Don't eat them. Some of the most bewitching plants are the most deadly and therefore particularly dangerous to small children who want to pick 'the pretty flower' and even put it in their mouths. Digitalis (foxgloves) with their purple, pink, yellow and white flowers are attractive to bees but poisonous to humans. The tender and exquisite blue aconitum (monkshood), sometimes found growing wild in shady chalk soils, dainty, dancing aquilegias, and the stunning range of irises – all are poisonous. So too are winter-flowering Lenten roses (hellebores), the delicate blue pulsatillas (pasque flowers) and moisture-loving, spring flowering, golden Caltha palustris (kingcups), often planted at the margins of ponds and found growing wild in wetland meadows.

There are several trees with poisonous fruits, flowers or berries, the most well-known being laburnum (golden chains). With its gorgeous, abundant, pendulous yellow flowers it has been an extremely popular garden tree, but its brown seed pods contain shiny black seeds – poisonous!

The delightful red yellow and orange berries that the birds love are frequently poisonous to humans , including those of the silver-leaved Hippophae rhamnoides (sea buckthorn). In wilder or untended parts of the garden there will almost certainly be familiar stinging nettles, and hogweed, which will blister and irritate the skin.

If garden boundaries abut pastures where sheep, cattle or horses graze, not only should these boundaries be stock proofed, but beware of planting poisonous hedging or other plants that can be reached by inquisitive livestock – they will lean over, pluck and chew indiscriminately on anything that looks enticing within a metre of the boundary. The leaves and fruits of conifers such as Juniperus (juniper) are poisonous to cattle and humans. So too the wonderful Taxus (yew) which forms such a marvellous, dense hedging and is invaluable in the creation of formal gardens There are many other shrubs and perennial weeds that are toxic to cattle and horses – ragwort, seen too often in neglected fields, common ligustrum (privet) hedging and hedera (ivy) are just a few.

Be a responsible designer and check online for a number of excellent books on poisonous plants.

Article by Sue Hook