Spring Gardening Tips: Propagating and Pruning Shrubs

Propagating shrubs

Layering is a simple method of propagation at this time of year for lax-stemmed shrubs, such as Amelanchier canadensis, celastrus, lilac (Syringa), wintersweet (Chimonanthus), and all species of Thus except Rhus typhina.

Peg down the selected branches into sandy loam, either in pots sunk in the soil or in the open ground at the base of the parent plant. The rooting process usually takes a year or more, after which the layers can be separated from the parent and replanted.

Some shrubs, including Amelanchier canadensis, produce offsets, and these can be severed in early spring. Pot the offsets in a proprietary compost until the autumn, and then transplant them to their flowering positions.

Divide the roots of rose of Sharon (Hypericum calycinum) and perennial sweet peas (Lathyrus), replanting the separated pieces in their flowering positions. Rooted suckers of kerria can be separated and replanted in a similar way.

Some other shrubs are raised easily from seeds, which can be sown in early spring in a cold frame or in a cool greenhouse. Sow seeds of clematis, cotoneaster, genista, laburnum and wisteria in boxes or pots of seed compost, lightly covering the seeds with sifted compost. Place them in a closed cold frame.

Seeds of eccremocarpus and shrub mallow (Lavatera olbia `Rosea’), sown in the same manner and placed in a greenhouse propagating frame with a temperature of 13-18°C (55-64°F), will germinate quicker than those sown in a cold frame.

When the seedlings are large enough to handle, prick them out into individual pots and grow them on in an open cold frame.

Camellias can be increased by taking 2.5cm (lin) long leaf cuttings in early spring. Insert them in potting compost in a propagating frame, maintaining a temperature of 13-16°C (55-61°F) until well rooted. Transfer rooted cuttings to individual pots and keep them in a cold, shaded frame until the following spring.

Take 5-7.5cm (2-3in) long root cuttings of Camps is radicans, Rhus typhina and Californian tree poppy (Romneya coulteri). Insert the cuttings singly in pots of compost and put in a propagating frame at a temperature of about 13°C (55°F). When the cuttings have rooted, repot the new plants and leave them in an open cold frame to grow on.

Pruning shrubs

If the winter has been severe — with hard frosts and heavy snowfalls — some of the more tender deciduous shrubs, such as cistus, hebe, Hydrangea macrophylla, laburnum and potentilla, will need light pruning to remove dead, damaged or weak stems.

Other shrubs, such as berberis, ivy (Hedera) and Hypericum patulum, will produce more vigorous growth after a light thinning out of old wood to maintain shape.

Caryopteris clandonensis, deciduous Ceanothus species and Hypericum calycinum should have the previous year’s shoots removed almost to the ground. Cut hardy fuchsias, Buddleia davidii and shrub mallow (Lavatera) hard back to live wood at the base from which new shoots will appear.

As soon as winter jasmine (Jasminum nudiflorum) and the early flowering shrub honeysuckle (Lonicera fragrantissima) have finished flowering, cut back the flowered stems — unless this was done already in late winter. With willows (Salix) and dogwoods (Cornus alba) grown for winter bark, cut stems hard back to promote fresh growth of brightly coloured stems.

10. June 2011 by admin
Categories: Garden Care, Propagation | Tags: , , | Comments Off on Spring Gardening Tips: Propagating and Pruning Shrubs

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