Propagating Plants for Hydroponic Growing
Plants properly propagated by conventional methods are quite suitable for use in NFT and bag growing hydroponic systems. Avoidance of root damage when transplanting into hydroponic systems greatly assists plant establishment and it is highly desirable that plants should be grown in individual pots. Plants can be propagated in ordinary disease free propagating media such as peat, bark or mixes of peat or bark with pumice,sawdust sand mixes, coir or rockwool cubes. It is not necessary to propagate plants in inert media, although it may be desirable to do so if disease free potting composts are not available. It is not necessary to wash roots clean of bark or peat before planting in NFT systems, and doing so often does more harm than good.
Adequate nutrition during propagation is vital for success. Many seeds absorb nutrients during their initial imbibition of water prior to germination, and it is important that the seed sowing media has a normal content of nutrients. Attempts to germinate seeds in inert nutrient free media often result in seedlings which remain poor and hungry looking throughout their propagation period. Much stronger seedlings result from germination in mixes with half strength additions of potting mix fertilisers
Seedlings can be pricked out into either a normally fertilised mix or into an inert media. Seedlings in inert media will need regular watering with complete nutrient solutions throughout the propagating period, seedlings in fertilised mixes may only require liquid feeding with NPK solution towards the end of the propagating period.
Original 1997 revised 30/9/99
This potting mix is suitable for propagating a wide range of greenhouse crops, including tomatoes, peppers, cucumbers, courgettes, melons, lettuce and many ornamentals.
The mix can be made from 100% peat (good quality peat such as Hauraki peat), or composted fine ground bark. Water holding characteristics and air space in these materials is good and there is no advantage from mixing any of these basic ingredients with sand, pumice or other materials.
Different liming rates are needed for these two materials:-
Other fertiliser additions are the same for peat or bark,
Fritted trace elements are the preferred source of trace elements as they release nutrients slowly over a long period of time, but cannot be leached out of the mix by over watering. An alternative is the Kinsealy trace element mixture given below. These chemicals are all water soluble and can be leached from the mix by over watering.
Kinsealy trace element mix:
Seed Germinating Mix The above potting mixes are too high in nutrients for ideal conditions for germinating seeds, but a seed sowing mix can easily be prepared by diluting either of the composts with an equal volume of peat or bark.
Liquid feeding These potting composts provide an adequate level of nutrition for about the first 4-5 weeks growth of tomatoes after sowing, but plants will benefit from liquid feeding from about the fourth week after sowing.