The Vegetable Garden

Glossary - H-L

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    Hardening-off – The process whereby transplants top growth and develop greater tolerance to stress.

    Hazard – The combination of a pesticide’s toxicity and your exposure to the pesticide

    Heavy soil – A soil that contains a high proportion of clay and is poorly drained.

    Heirloom cultivars – Cultivars that are more than 100 years old and whose seeds are passed down from generation to generation.

    Hill plantings – Planting multiple seeds together in clumps.

    Honeydew – A round melon with smooth rind and green flesh.

    Hotbed – A heated cold frame.

    Hot caps – Individual structures placed over a vegetable plant that warm the temperature and protect the plant against frost.

    Humus – A substance that results from the decay of organic matter by living organisms.

    Hyphae – A fine threadlike structure of cell formed by fungi affecting a plant.


    Incidental organisms – Organisms that have little or no impact on crop production.

    Inhalation exposure – Pesticide is absorbed by breathing-in through the lungs.

    Integrated Pest Management – An approach to pest management that uses a variety of techniques to identify and if necessary manage a pest.

    Intercropping – Planting more than one crop in an area at the same time.

    Interplanting (companion planting) – Growing two or more plants together in a close association.

    IR mulches – Mulches that allow infrared radiation to penetrate through the mulch but reflects photosynthetically active radiation.


    LD50 – Dose required to kill 50% of laboratory test animals.

    Leaching – the downward movement of water and nutrients from the soil surface to the water table due to gravity.

    Leafhoppers – Small (less than 1/2 inch long) wedge-shaped slender insects that disperse rapidly when disturbed.

    Leggy or spindly – Excessive and weak stem growth due to exposure to adverse environmental conditions.

    Legume – Plant that has a symbiotic relationship with rhizobium bacteria.

    Light soil – A soil that contains a high proportion of sand.

    Ligule – Structures that occur where the leaf blade attaches to the stalk.