Glossary P

P
Pan	A hard layer of soil below the surface.
Parasite	An organism that derives all of its food from a host, generally killing it in the end.
Parterre	A French-style formal garden.
Pathogen	An organism which causes diease.
Pelleted	Seeds which have been coated to make them more easily distributed. Fertilizers are shaped for the same reason.
Peat-bed	A bed which is raised and contains quantities of peat for plants that like acid soil in an otherwise alkaline area.
Peat block	A hard block of peat used to build a wall.
Peat pot	A flower or seedling pot made from peat and wood-fibre, it eventually decomposes.
Perennial	A plant that lives for more than three seasons.
Pergola	An arched structure which has climbers and ramblers trained to grow over it.
Perlite	Volcanic rock which is ground to a small size and added to composts.
Pesticides	A chemical used to kill insects and diseases.
Petiole	The stalk of a leaf.
pH	The degree of acidity or alkalinity. Below 7 is acid and above is alkaline. 7 is neutral
Photoperiodism	The ability to control the growing time of a plant by lengthening daylight hours.
Photosynthesis	The process by which a green plant makes carbohydrates from water and carbon dioxide, using light as an energy source and chlorophyll as the catalyist.
Phototropism	A plants response to light with movement.
Physic garden	Only medicinal plants are grown in this garden.
Picotee	Petals with different coloured bands around the edge.
Pillar	Fruit trees trained to form a columnar shape.
Pinching out	Remove the tips of shoots so that growth is concentrated lower down to make the plant bushier.
Piping	Obtaining a cutting by pulling out a shoot from a leaf joint, usually carnations.
Pistil	Female organs of flowers ie: the ovary, stigma and style.
Planting mark	The slight change in colour on the stem of a bare-root plant, indicating the depth at which it was planted before.
Pleaching	Narrowing the shape of a tree with pruning and intertwining.
Plug	A seedling or young plant grown in a cell or module.
Plumule	The first shoot of a seedling.
Plunge	A bed or area of organic matter or sand in which the whole pot can be placed up to its rim either to protect the roots from frost or to keep the plant cool and moist.
Pollarding	The removal of the branches of a tree hard back.
Pollen	Male fertilizing agent.
Pollination	The transfer of pollen from the anther to the stigma. Or the transfer of pollen from the male to female parts of the flower.
Pollinator	A special variety usually of fruit tree which provides lots of pollen to ensure fruiting on all the other trees.
Pompon	Bell-shaped flower.
Pore space	The spaces in soil provide space for aeration.
Porous tube	A hosepipe with holes all along its length for under soil irrigation.
Potager	A formal vegetable garden containing hedged compartments with fruit and vegetables growing within them.
Potash	A balanced fertilizer should always contain potash as it is essential for growth .
Potato fork	A fork with flat tines used for digging up potatoes.
Pot-bound	A plant which has been left for too long in the same pot and it has filled its container with roots, leaving no nutrients. Give it a new pot quickly!
Pot-on	Replacing and old pot with one that is slightly bigger, therefore giving space for the roots to grow.
Pot-off	Putting seedlings into their own pot.
Predator	An insect who preys on another that might be a pest.
Pre-emergence	A weedkiller that kills weeds even before they appear above ground.
Presser board	A piece of flat wood with a handle at one end to press flat compost or soil.
Pricking-out	The transplanting and spacing of seedlings.
Propagator	A glass or plastic box with a heated floor. Seeds can be brought on early in this warm, damp and humid atmosphere.
Propagule	A plant used for propagation.
Prostrate	A plant that grows flat to the ground.
Proteins	The essential ingredient of living cells.
Puddling	After a plant has been placed in a new situation it needs lots of water to saturate the soil.