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Gardeners' glossary A-Z

Jj

Use our easy-to-understand guide to help out with all those confusing gardening terms. From Acicular to Zebrinus, Annual to Zinc, you'll find a simple explanation below.

John Innes

The John Innes Horticultural Institute was founded in 1904, 'for the improvement of horticulture by experiment and research'. It was set up with money bequeathed by a London businessman of Scottish descent. John Innes composts were developed as an attempt to standardise compost formulae at a time when nurserymen were bringing a confusion of formulae to the market. The range includes John Innes seed compost, for seed sowing or rooting cuttings; John Innes potting compost No.1 for initial potting; John Innes potting compost No.2 for potting on; and John Innes compost No.3 for final potting of stock plants. Composts like this, which are soil based, should be stored in dry conditions and used within a month of purchase.

Joint

Another term for node. The point on a stem from which a leaf or leaf bud grows.

Juvenile

A young plant, the features of which differ at this early stage of its development from those of a fully mature specimen. Generally, a juvenile will be smaller and lack reproductive capability. In trees, juvenility may last many years.