Cultivating Garden Shrubs

Organic advice on choosing, buying, planting and looking after ornamental border plants.
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Shrubs form the framework of any border as well as attracting birds, butterflies and other insects. Some plants, like the beautiful butterfly bush (Buddleia davidii), prove irresistible to butterflies, which cluster round every nectar-filled bloom in summer.

Birds make use of shrubs for cover and food too. They particularly appreciate the berried shrubs like snowberry (Symphoricarpos doorenbosii) – a favourite because of its white berries and the dense cover it provides. Try to include a few native plants in the scheme because these are what will be most appreciated by wildlife.

Choosing Shrubs

When choosing shrubs, casting your mind forward at least ten years, to the time when the shrubs have grown to their maximum height and spread. After checking height and spread, think about a colour scheme, not forgetting to take into account the flowering season of the shrub and any others near it. It is also important to check preferences for shade and sunshine, soil type and acidity tolerance before making your final selection. Remeber that you can fill the spaces between small, young shrubs with annuals or other plants that have a shorter life.

Buying Shrubs

Like hedging plants, shrubs for borders can be bought as bare-rooted or container-grown plants. Container-grown plants tend to be smaller and more expensive – their advantage is that they can be planted at any time of the year instead of having to wait for the dormant season as you would with a bare-rooted plant.

Check all shrubs for signs of pests or disease and make sure they have a healthy root system.

Planting A Shrub

Although shrubs can be planted at any time of the year from the containers, there is, in my view, an advantage in buying field-grown, bare-rooted plants from a traditional nursery and planting during the autumn or early winter. A container-grown plant is more likely to suffer from the root ball drying out, so even if you do buy a plant in a container, it is still safer to wait until the autumn when the plant will not be losing so much water and the soil is more likely to remain moist.

If you plant shrubs (or trees) in an exposed spot, they dehydrate very quickly – this is especially so with conifers and other evergreens. Strong winds evaporate water from the leaf surfaces faster than the unestablished roots can take it up again so cells dry out and die. In a windy spot, it is essential, therefore, to protect newly planted specimens with a windbreak until they are established and their roots have had a chance to spread out.

  1. Dig a hole large enough for the roots or root ball. Mix the dug-out soil with a bucketful of organic matter.
  2. Water the plant well and remove the plastic container by cutting it off, being careful not to damage the roots with the knife.
  3. Plant at the level of the old soil mark on the stem. Sprinkle a little fine soil over the roots. Refill the hole and firm the soil down.
  4. Mulch around the shrub with a layer of organic matter to conserve moisture and inhibit weed growth.

Temporary Planting

If plants arrive when the weather is cold and the ground is frozen or if the soil is waterlogged, planting cannot go ahead. If you cannot plant immediately, it is wise to set the plants in a temporary trench, a technique known as “heeling in”. Shrubs can be heeled in for several weeks and lifted and planted in the normal way when favourable conditions return.

  1. Cut a shallow, V-shaped slit trench – building the soil up on the back wall. Lay the shrubs in a single row in the trench, at an angle of 45O, so that their roots are in the trench and their tops resting on the soil you have built up. This will ensure that they do not blow about, causing root damage.
  2. Cover the roots and lower stem with soil or peat and firm down with your boot. Cover with soil dug out of a second trench if you have a lot of shrubs to heel in.

Maintaining Shrubs

Feeding If you can provide shrubs with an annual mulch of well-rotted manure or compost, they will require little more. if not, give the whole border a dressing of blood, fish and bone meal in early spring, and a dressing of seaweed meal once every three years.

Watering Always pay particular attention to watering, especially in the first year while the shrubs are becoming established. This is particularly important with container-grown plants.

Pruning For many shrubs this should be carried out regularly. All shrubs can be shaped and, to some extent, kept smaller by regular cutting back, and many are pruned annually to produce flowering stems. Shrubs, such as the forsythia and the flowering currant (Ribes sp.), should be cut back hard immediately after flowering to encourage the bush to produce long shoots. The longer the shoots, the more flowers they are able to carry. Others like heather (Erica) and lavender (Lavandula) are trimmed with shears after flowering in order to keep them compact and prevent them dying out in the centre. Plants like broom (Cytisus hybrids) are pruned after flowering to prevent them producing seed.

Some shrubs, like the butterfly bush (Buddleia davidii), flower on wood made during the same season. These make long growths from buds that have been resting over winter, and they flower late in the summer. To increase the size of the blooms, all shoots made the previous year should be cut back hard in early spring.

Removing flower heads It is an advantage to remove the dead flower heads from many shrubs to increase the flower yield the following year. This is known as “dead-heading”. Plants like the heathers can be trimmed with shears immediately after flowering. Other shrubs like rhododendrons, have to be dead-heading by hand.

Removing flower heads from rhododendrons Remove the dead flowers very carefully as next year’s buds are immediately beneath and could come off with the old bloom. Pinch off the flowers between finger and thumb. This tidies up the plant and promotes more flowers for the following year.

Winter care If you plant in the autumn, winter frosts can lift the plants out of the ground again, so check them at regular intervals and, if they have been lifted, tread them back in.

Pests and diseases Pests like greenfly and diseases such as leaf spot attack a wide variety of shrubs, so check plants regularly and treat as necessary.

This extract is taken from DK Organic Gardening, by Geoff Hamilton, which you can purchase at all good book shops or online from Amazon.

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Last modified: June 10, 2021

Written by 3:48 pm Gardening