What are Cell Grown Plants?

What are Cell Grown Plants?

Cell Grown Plants are plants grown in small containers called cells. Multi-celled trays hold compost into which tree seeds are sown. The plants are grown with the trays g supported above the ground, allowing air pruning of the taproots and root tips. This ‘pruning’ promotes further fibrous root development, the key to future survival of a plant. Physical ridges on the individual cell walls prevent any root spiralling, and train the roots downwards.

Cell grown plants are extracted from their cells prior to despatch and are wrapped in protective packaging to ensure the root plug stays moist. The plants are planted with a completely intact, fibrous root system, which minimises stress, and ensures good survival.

The lifecycle of Cell Grown Fagus Sylvatica (Beech) at Cheviot Trees

A mature quality seed stand from which seed is collected.	A newly sown tray of seed.	After a few weeks, the trees start their second stage of growth.	Seedlings are now growing well and are regularly checked for pests, diseases and growth.

Trees have now matured and developed well. Having achieved a good root to shoot ratio, plants are moved outside.	At ordering, plants are hand graded to customers specification and are packaged ready for despatch.	At despatch the orders are checked and labeled ready for delivery. All relevant paperwork accompanies the order.	Quality plant production ensures healthy vigorous growth to maturity.

Frequently asked questions about Cell Grown plants
	Why Have a Specification? To provide guidance to specifiers and field practitioners on the way to ensuring that plants are correctly specified, with reasonable requirements being presented for nurseries to tender against, and that the plants actually supplied do indeed meet these minimum quality standards.
	What Quality Standard Are We Trying to Achieve? Whilst this guide deals only with Cell Grown Plants, the information presented is a summary of plant quality standards compiled by the Forestry Group of the Horticultural Trades Association and is in line with official EU standards on plant quality. Full details of the standards are available from the secretary of the forestry group of the HTA.
	Are Specifications Absolute? Not necessarily. Seasonal variations, differences in nursery practices, geographical location and genetic variation provide a complete spectrum of possible plant sizes. Not all grades of stock will be available every season. And when dealing with shrub species, such as roses and thorns, the nurseryman will often cut these back to non standard sizes to promote strong growth and better form. A grading of 15-30cms for cut back stocks may fall outside these proposed specifications but the plants may be entirely suited to their purpose.
	What Parameters Are Used? Given that the plants are healthy and vigorous, CELL VOLUME, HEIGHT and ROOT COLLAR DIAMETER are the accepted key criteria in drawing up the specification laid out on the following panel:
	*Can whip sizes (60-90cms) be supplied in Cells?* A. The usual sizes grown in British nurseries are up to 40cms for Conifers and up to 60 cms for Broadleaves. There is no perceived advantage in growing conifers (other than Larix species) in cells to sizes greater than 40cms. Larger broadleaved sizes (60-90cms) can be grown, and nurserymen will grow these to specification, and usually on contract, in larger cells.
	*How are the plants delivered?* A. The cells in which the plants are grown usually remain on the nursery. The plants are taken out of the cells and bundled together with the root systems protected by plastic wraps for delivery. Variations in the cell sizes used in different nurseries mean that blocks vary in the number of trees contained in a packaging unit — common figures are 12 for broadleaves and 20 for conifers.
	*Do Cell Grown Trees require special field protection?* A. No. If Cell Grown Trees have been obtained from a reputable nursery they will have been fully hardened. They require no protection other than that which would normally be given to any type of similar sized stock in the particular planting situation.
	*Can Cell Grown Plants be planted all year round?* A. It is advisable to avoid the period immediately after the young leaves have fully opened in early summer. The plants have a very high water demand at this time of year. Once the waxy cuticles on the leaves have hardened, planting into most soils should be possible — but remember, the plants are not completely drought resistant!
	Did you know? 60% of forestry planting stock world wide is now Cell Grown!
	If you have any questions you would like to ask us about Cell Grown trees we will be pleased to help. Either send us an e-mail or tel: 01289 386755 and speak with one of our friendly team.

Specification Guidelines - British Standards
Species Group	Minimum Cell Volume (cc’s)	Minimum Root collar diameter (mm)	Height Band (cm)	Notes
Conifers	50	3	10/20	Root collar diameter is measured at the base of the stem. Recommended minimum cell volumes are those considered necessary to achieve satisfactory proportions and shoot/root ratios. This table is intended to cover the majority of stock raised in cells by British nurserymen. On occasion, to meet specific requirements, it is possible that other cell sizes and root collar diameters may be acceptable—or indeed specified. Please ask for advice on non-standard specifications.
	100	4	20/40
	200	6	20/40
	300	8	40/60
Birch, Willow	100	3	20/40
	150	4	40/60
	200	5	40/60
	300	8	60/90
Alder, Beech, Blackthorn, Cherry, Hawthorn, Rowan, Sycamore, Crab Apple	100	4	20/40
	150	5	40/60
	200	6	40/60
	300	8	60/90
Holly	150	5	10/20
	150	7	20/40
	300	9	40/60
Ash, Hazel, Oak, Sweet Chestnut	50	5	15/30
	150	6	40/60
	200	6	15/30
	200	8	40/60
	300	10	60/90

The Handling and Planting of Cell Grown Plants
If the benefits of using Cell Grown Plants are to be fully realised, it is important to recognise that the final planting out can be the most vulnerable stage and root systems can be irreparably damaged if adequate care is not taken with the storage and planting of the plants themselves.

Remember

Cell Grown Plants are living things, and that whilst the root plugs provide a degree of protection, they will die, just like any other plant, if allowed to dry out.
It can take the nurseryman up to two years to build a fibrous root system, and careless aftercare two minutes to destroy it!

On receipt of the trees, if they have arrived packed in a box, the boxes should be opened and the trees stood upright if there is likely to be a delay in planting. Trees received during the dormant winter months can be held for several weeks in the boxes. Once the trees have become active they should be stood upright as soon as possible.

If Cell Grown Plants arrive on site, not boxed and standing upright, they should be stored in a sheltered location if possible. This will reduce water loss, even deciduous trees will draw some water from the cells in the dormant season. The leeward side of a wall or a few bales of straw are all that is required.

However the plants are received, they should be kept moist, the principle being to protect the trees from physical damage and desiccation.

When the time comes to plant, the trees should be carried on site in a method that will provide adequate protection. Purpose designed Harnesses are available which minimise damage to the root systems and provide enhances establishment — ask your nurseryman for details.

The type of tool used for planting is largely a matter of personal preference. However, the uniform and compact nature of the root plug does mean that a smaller spade than is used for bare-root stock can be used. Whichever tool is used it is important to ensure that the top of the root plug is covered by at least 1-2cms of the planting medium and the soil firmed around the rootplug.

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