R2102 4.1 Explain the considerations required when growing plants in containers

Question 1

Restricted Root Growth issue in pots (4)

Answer 1

1. Can dwarf the plant
2. Old mature roots become pot bound and are not as efficient at taking up moisture and nutrients
3. Little compost between roots to contain water and nutrients
4. To maintain good gaseous exchange there needs to be large pore spaces that do not collapse over time

Question 2

Plant containers (5)

Answer 2

1. Black pots heat up more than standard terracota coloured ones
2. White plastic pots can be up to 4C lower than other colours
3. Pot of white or light green can transmit sufficient light to affect root growth adversely and encourage algal growth
4. Clay pots are porous and water is lost from the walls by evaporation. The higher evaporation rate can keep the pots cooler which is benefical in hot weather
5. Biodegradable containers such as those made by paper are becoming popular. Some now have added nitrogen to avoid lockup of nitrogen.

Question 3

Water retention and supply in pots

Answer 3

1. Containers can dry out rapidly - especially if porous e.g. unglazed terracotta
2. Water retaining gels can be used to help keep water available to the roots
3. Compost can become easily waterlogged in winter - raising pots can improve drainage

Question 4

Compost in containers (5)

Answer 4

1. Needs to be stable to maintain structure so it does not slump down when wetted and lose all air from pore spaces.
2. Compost mixes usually contains only about 6 weeks supply of nutrients - if originally stored bad and has got wet this will be less.
3. Loam based composts hold nutrients better than peat / coir
4. Commercial compost is usually free from pathogens and weed seeds
5. Consider the wieght of the compost if containers are to be moved or relocated. Some tall containers need added grit to give stability and weight. Loam based composts such as John Innes no 3 are heaviest

Question 5

Soil v compost (4)
Issue with soil

Answer 5

1. Soil will contain weed seeds and possible pathogens
2. Will have poor AFP
3. Waterlogged easily
4. Extremely heavy