Growing perennials from Seeds
 

Perennial plants have become very popular in recent years due largely to changes in cultural procedures and marketing ideas. The term 'perennial' covers a wide range including herbaceous border plants, cut flower items and many of the varieties often referred to as alpine and rockery plants. As most items are raised from seed sown May – August, the bedding plant grower can programme to fill space during the summer season. Although some cultivars are propagated vegetatively, this leaflet covers production of species grown only from seed.

Seed Sowing

Our online catalogue gives recommendations for obtaining maximum emergence under the cultural notes for each genus. Most items can be sown in a well aerated glasshouse.
Seed is sown in trays of a well structured compost which have been previously watered. We would recommend the use of an approved pre sowing fungicide drench on the compost. Unless the seed is particularly fine it should be lightly covered with compost or a 50:50 mix of compost and Vermiculite. The trays should be wrapped in polythene or covered with glass and paper to restrict moisture loss. Once germination has taken place the covering must be removed and the seedlings allowed to develop in a cool, shaded, well-ventilated glasshouse.

Transplanting

As soon as they are large enough to handle the seedlings can be transplanted into the market container. This is usually a pot with a diameter between 7 and 11cm. Certain items such as Aubrieta, Sweet William and Viola can be transplanted into packs for multiple sales. The compost should be free draining with a balanced supply of nutrients so that they can develop quickly before growth ceases in the autumn. Smaller items like Campanula and Primula will benefit from being transplanted into small unit containers  and then potted up during the autumn.

Growing On

As long as ventilation is adequate, the plants can be grown in polythene tunnels or cold glasshouse structures. Cold frames can be used during the summer and autumn months but are not recommended during the winter. Plants can be grown pot thick and, wherever possible, carrying trays should be used to minimise handling. The young seedlings should be shaded during hot weather until they are well established. The plants must receive maximum light after that, but cool conditions must be maintained. It is soon important that the plants are not allowed to become dry during the growing season.
During the autumn the foliage will begin to die down and watering can gradually be reduced. At this stage the amount of air circulation around the plants is critical and adequate ventilation must be given. In late autumn the dead foliage should be removed, taking care that no damage occurs to the crown which will produce new spring growth. Fungicide sprays or drenches should be applied to prevent and cure any damping off. All debris should be removed immediately from the growing area.
Over winter the plants should be allowed as much ventilation as possible without causing damage to the crop or the structure during sever weather conditions. New growth will start to appear during the spring when watering can be increased and a balanced liquid feed will be beneficial. Plants must be kept clean to prevent disease carry over.

Pests and Diseases

Priority should be given to prevention of Botrytis and damping off diseases during the autumn and winter months by regular spraying and cleaning. Aphids, Caterpillar, Rust and Mildew should be treated with the appropriate chemical – if and when they occur.

Marketing

The main marketing period is spring and early summer when new young growth should be filling the pot.

Because few items are in flower, all pots should carry a colour pictorial label. Plants which do not sell by July can be cut back, if necessary, and potted on into a larger container to be sold during the autumn when there is a limited market.

General Information

We would recommend the following items for early spring sales:

Alyssum Mountain Gold

Geum Mrs Bradshaw

Anacyclus depressus

Heuchera Firefly

Aquilegia Music Mixed

Lupin Band of Nobles

Arabis Snowdrop

Lupin

Aubrieta Royal

Lychnis alpina

Bellis Pomponette

Myosotis

Dianthus alpinus

Nepeta mussinii

Doronicum magnificum

Primula Wanda

Erigeron Azure Fairy

Sagina

Erigeron Pink Jewel

Saxifraga Mossy Varieties Red & Rose

Eryngium planum

Sedum coccineum

Gaillardia Dwarf Goblin

Any chemicals referred to should be used only in accordance with the manufacturer’s instructions.