Herbaceous Perennials

Question 1

Characteristics

Answer 1

Non woody plants that live for several years.
Majority die to the ground in winter, but not all.
Some can become rather woody, particularly towards the end of the season.
Very wide range of shape, colour, form and texture.

Question 2

Shade

Answer 2

Some are shade tolerant e.g. astrantia Maxima, brunnera macrophylla.

Question 3

Weed control

Answer 3

Best way to control weeds in a herbaceous border is to incorporate ground cover e.g. alchemilla mollis, germanium macrorhyizum

Question 4

Herbaceous border

Answer 4

A traditional way to display herbaceous plants which comprises a rectangular beds usually adjacent to a lawn, with a barrier (such as a hedge) at the rear.
Sometimes a path is between the lawn and the plants so overhanging plants don’t damage the turf.

Question 5

Things to consider when planting herbaceous plants

Answer 5

Height - taller at the back, smaller at the front.
Flower and foliage colour - harmonising or complementary.
Texture - differences in foliage shape. Textures can be delicate and fine to course and bold. Too much fine can be a fuzzy blur, too much bold can be overwhelming. Nice balance is usually 1/3 fine.
Plant shape or form - plant size should be in scale.
Period of interest

Question 6

Soil preparation

Answer 6

As plants will be in the same place for several years it’s important to prepare the soil.
Most require well drained soil
Avoid making beds in areas where water collects, or choose bog tolerant plants.
For new site start prep the autumn before spring planting.
Control weeds with mulch, herbicide or digging and burial of weeds.
Hoe out any seedlings that survive.
Site should be level or gently sloping to reduce erosion.
Add 10-15ck of organic matter to improve the soil.
Apply 100g per m square of low nitrogen fertiliser and work into top 10-15cm of soil.

Question 7

When to plant

Answer 7

Best time to plant container-grown perennials varies by species.
In general plant summer and autumn flowering ones in spring.
For ones that flower in spring and early summer plant late summer and autumn.

Question 8

How to plant

Answer 8

Remove weeds that have popped up in previously prepared beds.
Loosen soil and dig a hole large enough to accommodate roots.
Tease out pot-bound roots and in severe cases use shears or a knife to make 3 or 4 cuts in roots to stimulate new growth.
Punch back any flowers or flower buds that have formed.
Plant at same depth and their container.
Water throughly after transplanting.
Mulching can help retain moisture.
Space plants properly.
Consider growing annuals between perennials until they grow to fill the space.
Bare root available when dormant.

Question 9

Propogation

Answer 9

By splitting - plant to same depth as previously.
From seed - can be direct sown or started in pots. Many can be slow or difficult to germinate.
Plants sown from seed may differ from parent plant.

Question 10

Mulching

Answer 10

Most benefit from mulching during growing season. Retains moisture and smothers weeds. Also improve soil as they break down.

Question 11

Watering

Answer 11

Some are drought tolerant.
Many need plenty water in dry areas or sandy soils.
Try to keep foliage and flowers dry to prevent disease.
If using sprinklers use in the morning so foliage drys quickly in the sun.

Question 12

Fertilising

Answer 12

Most do not need high levels of fertiliser.
Keep fertiliser off foliage to prevent burning. Slow release or organic fertilisers can reduce this.
Can work in a small handful of low nitrogen fertiliser in a ring around the plant in early spring, and perhaps 2 more times at 6 week intervals.
Fertilise late flowering plants once more in late summer.

Question 13

Staking

Answer 13

Some taller perennials tend to fall over when laden with flowers or in strong winds.
Locate so other plants can help support them or place next to a wall or other structure and fasten in with twine.
Instert stakes when plants are small and fasten to the stake as they grow.

Question 14

Pinching

Answer 14

Remove growing tips by pinching off the small, developing leaves at the end of stems. This forces more lateral growth making them plant bushier and shorter.
Aggressive pinching may delay flowering in some species.

Question 15

Pruning after flowering

Answer 15

Some early bloomers may flower again if cut back by half immediately after first bloom.
Many summer bloomers benefit from Curtin back to the leaves at the bottom of the plant after flowering.

Question 16

Disbudding

Answer 16

With some perennials l, especially those used for cut flowers like chrysanthemum, you can encourage fewer but larger blooms by removing the smaller lateral buds, forcing plants to put more energy into the terminal bud at the top of the plant. Or you can remove the terminal but and encourage more, but smaller, laterals.

Question 17

Deadheading

Answer 17

Remove spent flowers when they start to fade. This prevents plants wasting energy on seed production and keeps them looking neat. In some species this can encourage more flowering. It also prevents spreading by seed.
To attract birds don’t deadhead species with seed heads birds use as a food source e.g. echinacea purpurea.

Question 18

Cutting back dead leaves

Answer 18

Remove dead leaves to make room for new foliage.

Improves appearance and health of plant.

Question 19

Weeding

Answer 19

Annual weeds should be less troublesome as the ground isn’t turned regularly.
Control perennial weeds by hand weeding, hoeing etc.
Cultural control by mulching.
Herbicide can be used but never on flowering plants as this can be harmful to pollinators.

Question 20

Autumn care

Answer 20

Cut back most to about 75cm from the ground. Any closer may damage crowns.
Remove debris from garden to help prevent disease.
Cut back some species in spring..

Question 21

Division

Answer 21

Many perennials begin to decline after a few years. the centre of the clump may appear dead with little or no growth. This is a good sign the plant is ready to be divided.
Timing for this varies with species but for most it is when they are dormant.
In most instances dig out the entire plant, wash the soil off the roots, and cut or pull them apart into several pieces. Focus on preserving the newer, more vigorous roots and discard older diseased parts.
Replant into a larger area using the same spacing and soil prep as you would for new plantings.

Question 22

Pests and disease control

Answer 22

Choosing pest and disease resistant varieties Nd matching species to site will help reduce plant health problems.
Choose only healthy plants when shopping.
Remove diseased plant tissue and remove badly infected plants.
Remove dead foliage at the end of the season.
Proper watering and care to reduce stress.
Space apart to provide better air circulation.
Carefully monitor plants

Question 23

Specific pests and diseases

Answer 23

Aphids
Slugs and snails
Vine weevils
Stem or bulb eelworm.
Grey mould
Powdery mildew.