Plant dictionary: what does this term mean?
What is a root ball, and how much sun is partial shade? Look up a word and read in one or two sentences what it means. Handy when you are reading a product page or care tip.
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This is a general explanation, not advice for your specific plant. Times and figures are guidelines, and no rights can be derived from this overview.
A B C D E F G H I M N P R S T V W
A
Acid-loving
A plant that grows best in acidic soil, such as blueberries, camellia and rhododendron.
Aerial roots
Roots that grow above the ground and give the plant support or moisture, as with monstera and orchids. Don’t just cut them off.
Annual
A plant that germinates, flowers, sets seed and dies within one year.
B
Bare root
A plant delivered without soil around its roots. Plant it during the dormant period, roughly from November to March, when the ground is not frozen. This is common for hedges, for example.
Biennial
A plant that forms leaves in the first year and flowers and sets seed in the second year, after which it dies.
Botanical name
The scientific name of a plant, which is the same worldwide. The olive tree, for example, is called Olea europaea. The first word is the genus, the second the species.
Bud
The starting point of a new leaf, branch or flower. When pruning, you usually cut just above a bud.
Bulb
An underground food store from which a plant can regrow every year, as with tulips and daffodils. Take a look at our flower bulbs.
C
Clay pebbles
Baked clay balls that hold air and water. They are used for drainage and in hydroculture, where a plant grows without potting soil.
Clump
A group of stems and roots that has grown from one plant, as with many perennials and ornamental grasses.
Coming into leaf
Forming new leaves or shoots, often in spring.
Container-grown plant
A plant raised in a pot. It keeps its roots with it and can usually be planted all year round, except during frost or severe drought.
Crown
The part of a tree above the trunk, with the branches and leaves.
Cultivar
A cultivated variant of a plant species, also called a variety. The name goes in single quotation marks, as in Picea glauca 'Conica'.
Cutting
A piece cut from a plant that forms roots and grows into a new plant. Read how to take cuttings.
D
Deciduous
A plant that loses its leaves in autumn and grows new ones in spring. The opposite is evergreen.
Decorative pot
A pot that shows a plant off nicely. If it has no hole in the bottom, make sure no water is left standing in it. Take a look at our decorative pots.
Dividing
Digging up a large clump and splitting it into pieces. This keeps the plant strong and gives you new plants.
Dormant period
The time when a plant hardly grows, often in winter. It then usually needs less water and little or no feeding.
Drainage
The removal of excess water, for example through a hole in the pot or loose soil. Read why drainage matters for Mediterranean plants.
E
Espalier fruit
A fruit tree that grows flat along wires or a wall. It takes up little space and the fruit gets more sun. Take a look at our fruit trees.
Etiolation
A plant gets too little light and therefore forms long, floppy stems with few leaves.
Evergreen
A plant that has leaves all year round. Old leaves do fall, but gradually. Take a look at our evergreen plants.
F
Frost-free
A place where it does not fall below 0 °C, such as an unheated but well-insulated room. Also make sure there is enough light for plants that keep their leaves.
Full standard
A tree with a long bare trunk, so the crown starts high up. A half standard has a shorter trunk and a bush tree an even shorter one.
Full sun
A spot with at least about 6 hours of direct sun a day. This is a guideline too.
G
Garden fleece
A light cloth that protects plants from frost and cold wind. It lets air and light through. Read how to prepare an olive tree for winter.
Grafting
Getting part of one plant to grow onto the roots or trunk of another plant. This is common with fruit trees, to combine a variety with strong growth.
Ground cover
A low plant that covers the soil densely. This gives weeds less of a chance.
Growing medium
The material a plant grows in, such as potting soil or a mix with bark or perlite.
H
Hardening off
Getting a plant raised indoors used to outdoor air over a few weeks. Put it outside during the day first, and later at night as well.
Hardy
A plant that can withstand frost outdoors. How much frost varies per plant, and in a pot it is more vulnerable. Take a look at our hardy plants.
Humus
Decomposed plant material in the soil. It holds on to water and nutrients and makes the soil looser.
I
Invasive growth
A plant that spreads so strongly that it crowds out other plants. Some bamboo species do this with underground runners.
M
Mediterranean plant
A plant from an area with warm, dry summers and mild winters. Many of these plants cope badly with wet roots. Take a look at our Mediterranean plants.
Mulch
A layer of organic material on the soil, such as bark or compost. It holds moisture, slows weeds and protects the roots.
N
Night frost
Frost that only occurs at night. In spring it mainly damages young shoots and blossom. See the garden calendar for what you can do each month.
NPK
The three main elements in plant food: nitrogen (N) for leaves, phosphorus (P) for roots and potassium (K) for flowers, fruit and strength. The numbers on the packaging show the ratio.
Nursery pot
The usually plastic pot in which a plant was raised. You often put it inside a decorative pot or repot the plant.
P
Partial shade
A spot with about 3 to 6 hours of direct sun a day. This is a guideline, as sources count it slightly differently. More about the right position.
Perennial
A plant that lives for several years. Above ground it often dies back in winter, but it comes up again in spring. Take a look at our flowering outdoor plants.
Perlite
White, light grains of volcanic rock. Mixed into potting soil, they add air and improve drainage.
pH value
Shows how acidic the soil is. Below 7 the soil is acidic, above 7 it is limy. Most plants grow well in slightly acidic to neutral soil.
Pot feet
Small blocks under a pot, so it does not stand in water and excess water can drain away.
Pot-bound
The roots fill the whole pot and often grow in circles or out of the holes. Then it is time to repot. Work out the new pot size here.
Pricking out
Separating young seedlings and giving each its own spot or small pot, so they have room.
R
Renovation pruning
Cutting back old branches hard, so a shrub or tree forms new, strong branches.
Repeat-flowering
A plant that flowers more than once in a season, like some roses.
Repotting
Putting a plant in a larger pot or in fresh potting soil. Read more about repotting.
Rhizome
A thick underground stem in which a plant stores food and from which new shoots grow, as with iris.
RHS hardiness
A British scale from H1a to H7 that shows how much cold a plant can take. H1a is the most tender and H7 the hardiest. You can see the rating per plant in our winter hardiness guide.
Root ball
A plant’s roots together with the soil around them. If you loosen the root ball when repotting, do so carefully.
Runner
A stem that grows over or under the ground and takes root somewhere else, as with strawberries.
S
Seedling
A young plant that has just come up from seed.
Self-clinging
A climber that attaches itself to a wall without help, like ivy. Other climbers need wires or a trellis.
Self-fertile
A fruit plant that can bear fruit without a second tree or bush nearby. Others need a pollinator, meaning another variety that flowers at the same time.
Shade
A spot with less than about 3 hours of direct sun a day. Take a look at our houseplants and outdoor plants for shade.
Shoot
A young branch or stem that has grown this season.
Shrub
A woody plant with several branches from the ground or just above it. Take a look at our shrubs.
Specimen plant
A plant that stands alone and so stands out, such as one large tree or palm on the terrace.
Standard
A plant with a bare trunk and a crown above it, such as an olive tree or bay tree grown as a standard. This way it takes up little space at the bottom.
Summer pruning
Pruning in summer to keep the shape or slow growth, as with wisteria and espalier fruit.
T
Trunk girth
The circumference of the trunk in centimetres. Nurseries usually measure it 1 metre above the ground. Size 12-14 therefore means a girth of 12 to 14 cm.
V
Variegated leaves
Leaves with stripes, edges or spots in another colour, such as white or yellow. Variegated plants often need more light than green plants of the same species.
W
Wet feet
Roots that stand in water for too long. They then get too little air and can rot.
From word to answer
Know what a term means and want to find out more? Our plant care guides and the plant blog explain how to go about it. For a quick answer to your plant question, see plant help.
Frequently asked questions
What exactly does hardy mean?
That a plant can withstand frost outdoors. How much frost varies per plant. Look up your plant in the winter hardiness guide.
How much sun is partial shade?
Count on about 3 to 6 hours of direct sun a day. Full sun is about 6 hours or more. These are guidelines, as sources count it slightly differently.
What is the difference between a decorative pot and a nursery pot?
The plant was raised in the nursery pot. The decorative pot is the attractive pot around it, or the one you put the plant in. If it has no hole in the bottom, make sure no water is left standing in it.
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