5.1-5.3 Aquatic plants

Question 1

5 Categories of aquatic plants

Answer 1

Oxygenators (submerged) - Hottonia palustris (water violet)

Lagarosiphon major (goldfish weed)

Deep water - grow rooted in the soil base of a pond (that is 30-90cm deep) -

Nymphaea sulphurea

Nuphar lutea

Surface floating - Hydrocharis morsus-ranae

Stratiotes aloides

Marginals - grow in shallow water with water over the crown and roots submerged foliage above water surface. Planted in containers or in puddled clay

Iris pseudacorus

Caltha palustris

Bog plants in situ directly in the soil over the membrane - must be constantly moist. Will grow on temporarily waterlogged soil

Bog plants Gunnera manicata

Acorus gramineus ‘Variegatus’

Question 2

Oxygenators

Answer 2

Hottonia palustris (water violet)

Lagarosiphon major (goldfish weed) - considered a non-native invasive plant

Question 3

Deep water

Answer 3

Nymphaea sulphurea

Nuphar lutea

Question 4

Surface floating

Answer 4

Hydrocharis morsus-ranae

Stratiotes aloides

Question 5

Categories

Features

Answer 5

Oxygenators: submerged plants that help oxygenate the water and keep in clear of algae by competing for nutrients in the water

Deep water: rooted in the soil. Usually decorative and help reduce algae by cutting down on light

Surface floating: also cut down on light, but care must be taken not to let them smother and kill oxygenators

Marginals: grow in shallow water. Can provide habitat and protection for wildlife

Bog plants: thrive in moist soil - as above

Question 6

Marginals

Answer 6

Iris pseudacorus

Caltha palustris

Question 7

Bog plants

Answer 7

Gunnera manicata

Primula japonica

Acorus gramineus ‘Variegatus’

Question 8

Name

Answer 8

Hyrdrocharis morsus-ranae

surface floating

Question 9

Name

Answer 9

Stratiotes aloides

Surface floating

Question 10

Name

Answer 10

Lagarosiphon major

Oxygenator

Question 11

Name

Answer 11

Carex elata ‘Bowles’s Golden’

Question 12

Name

Answer 12

Nuphar lutea

Deep water

Question 13

Planting:

timing

method

principles

Answer 13

Usually between May and August

Deep water, submerged and marginal plants are planted 1. in soil in bed of pond or 2. in containers

50% of surface should be covered with foliage from deep water and floating plants to restrict algae growth. If coverage is greater than 70%, light levels are insufficient for submerged plants

Question 14

Division

Answer 14

Best divided after flowering when in active growth - spring

Remove container avoiding damage to liner.

Remove plant from container

Trim roots or tease roots through mesh sides if necessary

Remove compost

Separate/cut the plants into sections to include growing point and roots

Remove DDD material

Retain most healthy and vigorous setions

Question 15

Maintenance of water features

Answer 15

Lower plants (deep water aquatics or marginal) by removing bricks

Winter:

Ensure a small area of the pond remains ice free (trapped methane can be fatal to fish). Use hot pan to melt section or cover small ponds)

Remove leaves/debris from pond/bog areas

Restock with new plants and lift and divide overcrowded plants after flowering

feed container planted with slow release aquatic fertilisers

Summer:

Remove dead flower heads from marginals/bog plants

Top up water levels if required (rainwater)

Weed control on surface of water and in bog garden

Cut back over vigorous oxygenators

Remove excessive growth of floating weeds

Autumn:

Remove dead plant material and organic matter (netting helps)

Cut back oxygenators/marginals

Remove non-hardy plants for overwintering

Pond cleaning (draining first) should be done in autumn

Spring

May-August for new planting

Divide and re-pot eg Nymphaea species or Iris

Feed water lilies

Question 16

Problems in ponds

Answer 16

Algae: caused by high nitrate levels + excess sun

Control: increase shade (to 50-60%) but at least 33% and avoid tap water (nitrates). Filter the pond and empty no more than once every couple of years to maintain a healthy balance.

Barley straw can act as filter - bale or straw pads added in spring and left for 6 months when blackened. Algaecides clear water temporarily

Blanket weed: form of algae best removed by hand. Filters (eg UV clarifiers) kill the algae cells

Invasive plants eg. Lagarosiphon major pull out by hand

When pulling out weeds leave on side of pond to allow pond life to re-enter the pond

Ice: causes harm to fish and plant life - air holes allow gaseous exchange. Melt a hole or keep a ball floating in the pond

Question 17

Method for planting (baskets)

Answer 17

1. Line container with hessian
2. Fill with loamy compost (no organic matter and excessive fertiliser - especially N) Slow release aquatic fertiliser is inserted into container in spring. If garden soil is used must be free of fert, pesticides, weeds, pests and diseases
3. Insert and firm in plant and top with pea shingle to 2cm
4. The container should be well watered and lowered into the pond (may be lowered using ropes and 2 people)
5. Use bricks blocks if required to raise to right level