Herbaceous Borders:

Introduction – The Basics
A traditional herbaceous border is, usually, comprised of a rectangular (or sometimes slightly curving) bed which is backed by a hedge or wall. This bed is then filled with groups and swathes of herbaceous perennials, graduating down in size from the very tall at the back to the smallest at the front. Diagram 3 shows an example of a herbaceous border. In this example the bed is backed by a hedge, and an access path (for ease of maintenance) is provided at the rear of the border. However, if the border is backed by a wall or fence, then climbers or wall-trained shrubs may be used to increase interest. The tall plants are placed at the back of the bed, with mid-height plants in the middle, graduating down to short and creeping plants at the front. Thin swathes (or ‘arms’) of taller plants may be brought forward to add interest, or tall/showy “dot” plants used near the front. Seasonal bulbs might also be added at the front of the border.

Planning and Maintenance
When planning a herbaceous border, preparation of the site is of utmost importance, as herbaceous beds that are well prepared should not then require major work for a goodly length of time. If starting from scratch, and if the time is taken to prepare the ground accordingly, one need only lift the contents of the bed after a period of three or four years to divide the plants and to refresh the soil through digging (and the application of more organic matter).

Although the lifting and division of plants need usually be undertaken only once every few years (as a rule of thumb, although particularly vigorous plants may need to be dealt with more frequently), one might need to re-evaluate the position of a particular plant (or group thereof) in the meanwhile if the performance is poor or if the plant turns out not to be well suited to the site. Other than that, maintenance of the bed consists only of weeding, dead-heading, removal of debris and feeding during the growing season. Other tasks such as staking may also be required, although this generally depends on the plants being grown. Pest control, as always, should be kept in hand.

Alternatives
Not all gardens or gardeners are suited to a traditional herbaceous bed, some instead prefer to use hardy herbaceous perennials in other ways. A popular alternative is the ‘island bed’ – a bed of informal shape which is set into a lawn (see Diagram 4). As this type of bed is viewed from all angles (as opposed to mainly the front with a traditional herbaceous bed/border), there are usually few very tall plants, although a standard or specimen plant may be placed at the centre to add height (e.g. Corylus contorta avellena, the contorted hazel or a standard Buddleia davidii, the butterfly bush). Although some plants may still require staking, depending on your preferred varieties, it is more usual to select cultivars which are self-supporting.

Gardens which feature ponds may also utilise appropriate herbaceous perennials in the moist area around the pond, or in bog gardens. Plants which love moist conditions and are ideal as ‘bog’ plants include hostas, kingcup/marsh marigold (Caltha palustris), giant rhubarb (Gunnera manicata), candelabra primula (Primula pulverulenta), umbrella plant (Darmera peltata), and purple loosestrife (Lythrum salicaria).

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Ground-Cover Shrubs:

The main advantage of using ground cover shrubs is the suppression of weed growth – as they (ideally) cover (carpet) the ground fairly thickly, they prevent light from reaching the soil, thereby preventing germination of weeds. Any weeds that do manage to come up will then have to compete for light, water and nutrients with the cultivated plants. Another advantage is purely aesthetic – ground cover shrubs are far more attractive to look at than expanses of bare soil.

Plants for ground cover can be chosen to enhance the existing plantings, or in a herbaceous border they can be used to provide interest during those periods when the ‘main’ planting is looking drab. In both cases, evergreen shrubs are perhaps the better choice as they cover the ground all year around, whereas deciduous plants will eventually let the light through to the soil (when their leaves fall) where any weed seeds can then start to grow. On steep slopes ground cover planting can help prevent/lessen soil erosion and water run-off.

The main disadvantage of ground-cover shrubs is that they will, unless wisely chosen, compete with any other plants which they surround, and that they add to the amount of work that needs to be done in the garden (again, dependant on the type chosen). Overly vigorous varieties may not just compete for water and nutrients, they may also (in extreme cases) attempt to smother other plants! Another disadvantage is that, while ground cover provides a habitat for beneficial insects, it can also provide a home to slugs and snails – try not to grow plants which are prone to slug/snail attack in amidst ground cover planting.

Six shrubs that are suitable for use as ground cover are:
Arctostaphylos uva-ursi
Bearberry (the common name for A. uva-ursi) is an evergreen trailing shrub that reaches a maximum height of between 10-20cm and has a spread of approximately 1-2m. It produces pink or white flowers in mid to late spring and these are followed by red berries. Although bearberry will tolerate poor soils, it must be of an acidic pH.

Empetrum nigrum
Crowberry is a heath-like shrub which is frequently found on moorland and in coastal areas (usually preferring an acidic soil pH). It generally reaches around 15cm in height and forms a dense matt of foliage. It produces inconspicuous flowers (purple) in the spring and the black/blue-black berries develop in late summer to early autumn.

Vaccinium vitis-idaea
The cowberry, or mountain cranberry, is another acid-loving evergreen which will grow in full sun or light shade. Very slow-growing, it will eventually (over many years) reach a height and spread of 30cm x 1m. The fruits are edible, although apparently more palatable after a frost, can be used as a substitute for cranberries.

Calluna vulgaris
Commonly known as heather, or ling, C. vulgaris comes in many varieties, most of which are suitable for ground cover on acid soils. Their evergreen foliage (which ranges in shade from dark green to light green) and spikes of white to crimson flowers make them a useful and beautiful addition to the garden.

Hypericum calycinum
H. calycinum, or Rose of Sharon, is related to the more commonly known St. John’s Wort (H. perforatum). H. calycinum is a semi-evergreen shrub with a creeping rootstock, particularly suitable for dry shady areas where ground cover is required.

Juniperus communis ‘Repanda’
This is a dwarf variety of juniper with a creeping habit – its slow growth (reaches a height and spread of 30cm x 2m after approximately 10 years) makes it ideal for small and low maintenance gardens. The foliage is tolerant of direct sun, rarely scorching, although it may take on a bronze hue during the winter.

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Zonal Pelargoniums:

Introduction – The Basics
Zonal pelargoniums are bushy plants with succulent stems and rounded leaves (which span between 4-14cm dependant on variety) that are often bi-coloured; the flowers can be single, double or semi-double. The types raised as bedding plants are usually single-flowered F1 hybrids – these flower in their first year and come true to colour from seed.

Propagation
Seeds should be sown under glass in late winter and early spring, at an optimum germination temperature of around 13-18°C. Use a regular potting compost, maintaining good horticultural hygiene to help prevent instances of damping off and other fungal infections. Ensure that pots, trays or rootrainers are clean before filling with compost. Sow seed thinly into trays, or two or three per pot/cell. If sowing in trays then seedlings should be pricked out into individual 2-3inch pots after the second pair of leaves have appeared. If several seeds were sown into pots or cells then the strongest seedling should be allowed to remain, with the weaker ones being discarded.

General Tips
With pelargoniums being grown for bedding one should ‘stop’ the plants when they reach the desired height – this means pinching out the ‘leader’, the top of the main stem. This will encourage the plant to produce side shoots and become bushier, which will lead to stronger plants and a better display. Continue to pinch out the tips of shoots to help the plant remain bushy.

On a similar note, if the light coming into the greenhouse or shed is mainly from one side then plants should be turned regularly to help them to grow evenly. Plants will always grow towards the source of light, thus if they stay in the same position they will tend to grow that way, leaving rather sparse growth towards the back. Turning plants once a week while they are under glass will help them to develop evenly.

Pests & Diseases
As diseases go, zonal pelargoniums are particularly prone to rust – again, good hygienic practices may help to prevent this; they may also suffer from botrytis, in which case any infected parts should be removed and destroyed as fungicides have little effect.

Insects which may prey on zonal pelargoniums are leaf-hoppers (which can transmit viral diseases – a systemic spray will take care of them), aphids (use a proprietary spray to get rid of severe infestations, or if only a few are present they can be squashed with a thumb). Another pest which may affect pelargoniums raised in pots are sciarid flies (also known as fungus gnats), the larvae of which consume the roots and stems of the plants. Infestations of sciarid flies can be prevented by placing a layer of horticultural sand or grit over the top of the soil in the pot – this prevents the adult flies from laying their eggs.

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Cyclamen:

The Basics
The cyclamen cultivars which are commonly grown in pots indoors for decorative purposes all stem from Cyclamen persicum, which grows in the wild in the Mediterranean. The cultivars have been bred to be particularly decorative (commonly called ‘Florists Cultivars’), with a wide range of flower-colour, picotee forms and some with frilly petals.

Planting Medium
When growing cyclamen in pots a well-drained potting medium should be used. A proprietary potting compost, with the addition of some grit to further aid drainage and some organic matter is suitable, although the Cyclamen Society suggest the following mixture:
“a good general mix can be made by mixing together 3 parts John Innes No.3 compost with 2 parts sharp potting grit, and either 2 parts decayed leaf litter (leafmould) or 1 part peat.”
Whether a gardener uses plastic or terracotta containers for planting is a matter of personal preference, although with clay pots some growers plunge the pots up to the rim in sand (in, say, a greenhouse bed) to help maintain a moist, but not wet, situation for the compost.

Planting Depth
Cyclamen tubers should be planted with the tuber at soil level (species other than C. persicum may require a greater planting depth), with the pot then topped up with a 1cm layer of grit/fine gravel – this will help to keep the crown dry and therefore aid prevention of crown rot. When cyclamen require re-potting, this should be undertaken during the tuber’s dormancy, although in particular it is best done after the roots have started growing again (late July and throughout August).

Feeding & Watering
Feeding of cyclamen should be restricted as over-feeding can lead to an overproduction of foliage over flowers. Watering may be done from either above or below – although when watering from above care should be taken not to splash the leaves as moisture on the leaves may increase the chances of botrytis, especially indoors where there is no breeze to help water droplets evaporate. Cyclamen prefer to be watered thoroughly and then allowed to dry out (to some extent, not until the plant is dehydrated!) before being watered again.

Temperature
In the wild C. persicum flowers in the Mediterranean winter which is quite cold. Therefore if you notice that your cyclamen isn’t thriving, it may be that the temperature of the room in which it is kept is too high. Keep cyclamen in the coldest part of the house for best performance, and ensure that they receive as much natural light as possible.

Pests & Diseases
A few pests and diseases which affect cyclamen are:
Vine weevils - The black vine weevil adults cause damage to the leaves of cyclamen, which is minor and only affects the aesthetic appeal of the plant. The larvae, however, consume the roots and tuber, effectively killing the plant. Where infestation occurs, a proprietary chemical control may be used, or a biological control such as Nemasys, which uses nematodes to get rid of the larvae. If an infestation is particularly severe then either sterilisation or disposal of the compost may be necessary. Good horticultural hygiene (e.g. cleaning up debris, which is a possible breeding ground) can help to prevent this pest.
Cyclamen mite - These microscopic pests can cause deformed/discoloured leaves and also distortion of the flowers and flower stem. No adequate control measures are available to amateurs.
Fungal Diseases - Cyclamen grown under glass or as houseplants can succumb to a wide range of fungal diseases, too numerous to list here. Botrytis, or grey mould, is probably the most common. Good circulation of air and practice of horticultural hygiene can help to prevent this.

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