This gardening quiz has 70 free questions with answers and covers everything from the potting shed to the palace grounds: how compost, soil pH and NPK fertiliser work, why hydrangeas change colour, what deadheading and espalier mean, and which plants are annuals, biennials or perennials. It visits Kew, Versailles, Keukenhof and Monet's Giverny, meets Capability Brown, Gertrude Jekyll, Luther Burbank and Monty Don, and takes in tulip mania, victory gardens, the Chelsea Flower Show and the seed vault buried in Arctic permafrost. The early questions suit anyone with a windowsill herb pot; the later ones will stretch allotment veterans and RHS members with the origins of the lawn mower, the science of nitrogen fixation and the wisteria that weighs 250 tons. It makes a good round for a garden club evening, a horticulture class or a rainy-day family quiz. Every answer has been checked against Wikipedia and reference sources, and each question shows an explanation and its citation once you answer.
30 of 70 questions with answers and explanations. Play the quiz
Q 01What is a plant that completes its whole life cycle in a single growing season called?
An annual
Peas are a classic example; the plant flowers, sets seed and dies within the year.
Q 02A biennial plant such as parsley or a Canterbury bell takes how long to complete its life cycle?
Two years
The first year is spent growing leaves and roots; flowering and seed come in the second.
Q 03In a compost heap, grass clippings and food scraps are the 'green' waste. What are they rich in?
Nitrogen
The 'browns', such as woody stalks, paper and wood chips, supply the carbon to balance them.
Q 04On a fertiliser bag's N-P-K numbers, what element is K?
Potassium
The N-P-K trio are the three macronutrients most modern fertilising focuses on.
Q 05A soil with a pH reading below 7 is described as what?
Acidic
Most soils fall between 3 and 10, and blueberries and rhododendrons want the acid end.
Q 06The flowers of many hydrangeas act as natural pH indicators. In soil with a low pH, what colour are they?
Blue
The same plant turns pink in alkaline soil; the name means 'water vessel' in Greek, after the shape of the seed capsules.
Q 07Charles Darwin's last book, published in 1881, was a study of which garden helper?
The earthworm
He estimated an acre of arable land could hold 53,000 of them; modern research puts rich farmland at up to 1.75 million per acre.
Q 08What is the horticultural practice of removing spent flowers from a plant called?
Deadheading
It stops the plant pouring energy into seed and often prompts a second flush of blooms.
Q 09In grafting, the upper part is the scion. What is the lower, rooted part called?
The rootstock
Almost every commercial apple tree is grafted, because apple seeds do not grow true to the parent.
Q 10What is the technique of training a fruit tree flat against a wall or frame called?
Espalier
The word is French, and free-standing single-tier versions are called step-overs.
Q 11The Chinese art that parallels Japanese bonsai is called what?
Penjing
Korea has bunjae and Vietnam has hòn non bộ; the loanword bonsai has become the English umbrella term for all of them.
Q 12Which of these shrubs is a classic choice for topiary?
Box
Yew, bay, holly and privet are the other regulars, all dense and tolerant of hard clipping.
Q 13Kew Gardens in London, a World Heritage Site, was founded in which year?
1759
Its herbarium holds more than 8.5 million preserved specimens, one of the largest in the world.
Q 14Which landscape designer perfected the French formal garden style at Versailles?
Q 21Monty Don took over as lead presenter of BBC's Gardeners' World in 2003, replacing whom?
Alan Titchmarsh
The change was made at his predecessor's suggestion, and Don has fronted the show from his own garden, Longmeadow.
Q 22In 1893 the US Supreme Court ruled that, for tariff purposes, the tomato was a what?
A vegetable
Botanically it is a berry, but the court in Nix v. Hedden went with the popular definition: served with dinner, not dessert.
Q 23The 'Three Sisters' planted by indigenous peoples of the Americas are maize, beans and what?
Squash
The corn supports the beans, the beans fix nitrogen and the squash leaves shade out weeds and hold moisture.
André Le Nôtre
The gardens cover about 800 hectares and their fountains still use much of the hydraulic network built for Louis XIV.
Q 15About how many flower bulbs are planted each year at Keukenhof in the Netherlands?
7 million
The 32-hectare park in Lisse is best known for tulips but also grows hyacinths, daffodils, lilies and roses.
Q 16The village of Giverny in Normandy is famous for the garden of which painter?
Claude Monet
The water-lily pond and Japanese bridge he built there became the subject of his last great series of paintings.
Q 17The Hanging Gardens of Babylon are unique among the Seven Wonders of the Ancient World for what reason?
Their location has never been established
Legend says Nebuchadnezzar II built them for his wife Amytis, who missed the green hills of her homeland; some scholars now place them at Nineveh.
Q 18How did the 18th-century landscape gardener Lancelot Brown earn his famous nickname?
He told clients their land had potential for improvement
He designed more than 170 parks, including Blenheim, and many survive today.
Q 19Gertrude Jekyll is best remembered for her garden partnership with which architect?
Edwin Lutyens
She created more than 400 gardens and wrote over 1,000 magazine articles; Munstead Wood was their first collaboration.
Q 20Which famous white-petalled garden flower was among Luther Burbank's 800-plus plant varieties?
The Shasta daisy
His other successes include the Santa Rosa plum, the plumcot and a spineless cactus for cattle feed.
Q 24Tulip mania, the famous speculative bubble, collapsed in which year?
1637
A single bulb of the Viceroy variety was offered for 3,000 to 4,200 guilders, when a skilled artisan earned about 300 a year.
Q 25Apples, pears, strawberries, cherries and almonds all belong to the same botanical group as which flower?
The rose
The Rosaceae also give us plums, peaches, raspberries, quinces and hawthorn.
Q 26It is often said that sunflowers follow the sun all day. What do mature sunflower heads actually do?
Face a fixed direction, usually east
Only immature buds track the sun; the heads lock in place, mostly facing east, once the flowers open.
Q 27The dahlia is the national flower of which country?
Mexico
The plants were known only to the Aztecs and their neighbours until the Spanish conquest; the tubers store inulin rather than starch.
Q 28Ladybirds are welcomed by gardeners because they eat what?
Aphids
The 'lady' in the name refers to the Virgin Mary, and their bright colours warn birds that they taste bad.
Q 29The 'lady' in ladybird refers to whom?
The Virgin Mary
In North America they are ladybugs, and entomologists prefer 'lady beetles' since they are not true bugs.
Q 30Which First Lady planted a victory garden on the White House lawn in 1943?
Eleanor Roosevelt
The wartime campaign pushed the number of British allotments to about 1.4 million by 1943.