Visit Ashwood Nurseries today - for sat navs use postcode DY6 0AE

Glossary H

Height of Plants

The height stated in our plant descriptions is an approximate height after 10 years for all woody plants, which includes trees, shrubs, conifers, roses and hydrangeas. It is not an exact science as so many factors can influence a plant’s height including soil type, aspect, microclimate and seasonal climatic variations.

Height of Shrubs (including hydrangeas and rhododendrons): The height stated in our descriptions is an approximate height after 10 years.
After 10 years, most shrubs will continue to grow, but usually at a slower rate. A shrub which reaches 2 metres (6ft.) in 10 years will generally achieve another 10% to 20% increase in height over the next 10 years.
Some shrubs (e.g. some acers) develop more tree-like proportions as they mature and, where this is the case, we will state it in the description.

Height of Trees: We have classified trees as those woody plants typically developing a single trunk with lateral branches. In our descriptions we classify their size as Very Small, Small, Medium or Large.
Very Small trees: up to 1.25 metres (4ft.) after 10 years
Small trees: up to 3 metres (10ft.) after 10 years
Medium trees: up to 5 metres (16ft.) after 10 years
Large trees: over 5 metres (16ft.) after 10 years
After 10 years, most trees will continue to grow at around the same rate per year. A tree that reaches 3 metres (10ft.) in 10 years will generally double in height over the next 10 years. If it is a top-grafted weeping tree the increase in height will be minimal after 10 years.

Height of Conifers: The height stated in our descriptions is an approximate height after 10 years.
After 10 years, most conifers will continue to grow at around the same rate per year. A conifer that reaches 4 metres (12ft.) in 10 years will generally double in height over the next 10 years.

Height of Roses: The height stated in our descriptions is an approximate height after 10 years.
After 10 years roses are more variable in growth rates but, as a general rule, most bush roses of all types will not grow much more after 10 years. Climbing and rambling roses are an obvious exception, but most of these can be controlled by regular pruning.

Height of All Other Plants (including hellebores, hepaticas, cyclamen, snowdrops, lewisias, salvias, herbaceous plants, ferns, heathers and alpines): The height stated is an approximate flowering height which is usually achieved within a year and generally will not vary very much after that.

Hardiness Rating

The hardiness rating we use for plants follows closely (but not entirely) the RHS guidelines and is based mainly on the plant’s tolerance of winter temperature. It is not an exact science as so many other factors can influence a plant’s hardiness including soil type, aspect, microclimate and seasonal climatic variations.

‘Hardy’ corresponds to RHS Hardiness Rating: H4 and H5, with plants tolerating a Winter Minimum Temperature Range: -.5 to-15.
Plants described by us as hardy should survive winters throughout most of the UK apart from in high altitudes or very northerly locations. Some plants classed as hardy may still benefit from a sheltered position and this is conveyed in individual plant descriptions. Hardy plants may still suffer some damage in severe winters or on heavy or poorly drained soil. Bear in mind that if these plants are grown in pots, they are more vulnerable to harsh winters.

‘Semi Hardy’ corresponds to RHS Hardiness Rating: H3, with plants tolerating a Winter Minimum Temperature Range: 1 to-.5
Plants described by us as semi hardy should survive winters in mild parts of UK (including sheltered coastal areas) except in severe winters or when sudden early frosts occur, when the plant may not survive. Semi-hardy plants may survive winters elsewhere with the protection of a south- or west-facing wall or in a sheltered microclimate e.g. an inner city garden.

‘Tender’ corresponds to RHS Hardiness Rating: H2 with plants tolerating a Winter Minimum Temperature Range: 1 to 5
Plants described by us as ‘tender’ are tolerant of low temperature but will not survive being frozen. Tender plants can be grown outside once the risk of frost is over.

Hardy Annual

A plant that completes its whole life cycle within a year, but whose seeds can survive sub-zero winter temperatures, and whose seedlings can endure spring frosts without damage. This allows for an earlier start to the lifecycle.

Herbaceous

A non-woody plant, where in most cases, the vegetation above ground dies back to the soil surface at the end of the growing season each year, re-shooting the following spring.

Herbicide

A chemical used to kill unwanted plants. Can be contact or systemic, with some chemicals burning/killing the plant while some act to interfere with the growth of the plant by mimicking naturally occurring plant hormones. Some herbicides can also be selective, for example herbicides to kill weeds in lawns without damaging the lawn.

Hermaphrodite

Bisexual flowers, containing both male and female organs (stamen and pistils) often capable of self-pollination.

Honeydew

A sticky substance, excreted by sap-sucking insects such as aphids, which coats the lower leaves and stems, often developing sooty mould.

Humidity

Humidity refers to the amount of water in the air, present as water vapour and is given as a percentage. High humidity reduces transpiration, reducing moisture lost by the plant at higher temperatures.

 

Increased humidity can also help to reduce the temperature, and can help to combat certain pests in greenhouse environments that prefer a dry environment, e.g. red spider mite.

 

The easiest way to increase humidity is to damp own paths or place trays of damp grit beneath plants.

 

Too much humidity can cause fungal problems, to combat this increase air flow and ventilation to reduce humidity.

Hybrid

A hybrid plant results from the cross fertilisation of two or more different plant species or genera.