INDOOR CROPS

Soilless

1 July, PGU.

Why is growing media important?

Growing medium - material where plants grow

Media Provides nutrients by absorption through roots

Anchors plants

Contains pore spaces which provide oxygen for roots

Provides favorable environment for microorganisms

What are the different types of growing media?

Soil Thin layer of earths curst that provides for

growth of plants

Soilless medium Contains no topsoil

Components of Growing Media

1. Peat Moss- moisture and nutrients 2. Bark- substitution for peat moss 3. Sand- increases aeration and drainage 4. Perlite - increases aeration and drainage 5. Vermiculite- holds nutrients and moisture

Peat- lite mixes- common formulation of

soilless media

Bark-based mixes- commercially prepared bark based mixes that are substituted for sphagnum moss.

Perlite

Volcanic material

Provides drainage and aeration

Vermiculite

Heat treated mica

Holds moisture

Sterilized organic compounds Loosen the medium

Create larger air spaces between the particles

Include:

- Peat Moss

- Sphagnum Moss

- Leaf Mold

- Bark

Peat Moss

Sphagnum Moss

Leaf Mold

Bark

Soilless Structures

Environmental conditions Lighting * In many climates it will be necessary to grow indoors under artificial lighting.

* This requires careful practice because it is difficult to replicate the

performance of sunlight.

* High Intensity Discharge (HID) lamps are a type of light that uses electric

arc to produce light, (ex: Metal halide and high-pressure sodium lamps). Used

in a combination these two types of lamps can be a substitute for natural

sunlight.

Ventilation

Is a key consideration

especially when

growing indoors under

artificial lighting. The

combination of lighting

and plants generates

excessive amounts of

heat and humidity

which will harm plants

if not properly

controlled.

Irrigation systems and parameters pH and CF

Conductivity (EC) for hydroponics

Conductivity Meter Device used to help monitor the concentration of nutrient solutions. (EC

meter, CF meter or TDS meter).

Conductivity represents the ease with which a solution conducts electricity.

Solid substances known as 'salts' (e.g. sodium chloride, potassium nitrate), yield 'ions' when dissolved in water. 'Ions' permit the flow of electricity

through the solution.

Increasing the concentration of ions improves the ease with which the solution carries an electric current and therefore causes a higher conductivity.

Hence, an EC meter can be used to detect the presence of salts and their approximate concentration in water.

Not all solutions or liquids conduct electricity Ex: petrol, alcohol and distilled water.

pH measurement and control To ensure the long-term stability of nutrient solutions, it is important to maintain

the pH between 5.0 and 6.5. This helps ensure all nutrients are available for root up-take. It also minimizes the risk of plumbing blockages.

Optimum pH of nutrient solutions

The key reason for controlling the pH of nutrient solutions is to make sure that the individual elements in the nutrient remain soluble.

If certain elements become insoluble, a white precipitate will form on the bottom of the reservoir.

Hydroponics The word hydroponics is comprised of two Greek words: hydro (water) and pono (labour)

Growing plants in a nutrient solution consisting of water and dissolved

nutrient salts.

Advantages

Complete control of nutrient solution Greater yield per unit area through closer spacing of

plants

Less spreading of roots Reduced need for control of weeds, disease, and

insects due to absence of soil

One of the most exciting challenges of indoor gardening is producing out of season fruits and vegetables.

Change the way in which strawberries are grown in NZ. To obtain quality plant and fruit production, under protective cultivation.

INDOOR CROPS HYDROPONICS

Fruit, A frame hydroponics, showing root system of Camarosa strawberries, Dural NSW

Hydroponic systems are classified according to:

Substrate systems Sand culture- plants grown in sterilized sand with

individual drip irrigation

Gravel culture- involves irrigating plants grown in gravel for mechanical support.

Bag culture- uses plastic bags that are filled with substrate, such as rockwool, peatlite, and sawdust. Drip irrigation used to supply nutrient solution.

Cocotek mat rockwool

Bare root systems

Aeroponic system

Involves plant roots suspended in air with a fine mist of oxygen-rich nutrient solution sprayed on them a regular intervals.

Continuous flow system Involves using shallow pools with panels containing plants floating on the surface

Flood & Drain (or Ebb & Flow) In flood & drain systems, the nutrient is fed from beneath. This

process floods the root zone to a pre-determined maximum level after which all the nutrient is allowed to drain back into the reservoir.

This process is controlled by a pump, timer and a specialized inlet and overflow device:

Inlet: This also serves as the drain outlet. It is positioned as close as possible to the base of the flood & drain tray. Once pumping stops, the nutrient is able to fully drain into the reservoir via the inlet and pump.

Overflow: This is positioned at the maximum desired flood height. This means pumping can only flood to the height of the overflow. Suitable media for flood & drain include expanded clay, perlite or even none at all. The water holding capacity of the medium determines the feeding frequency.

Advantages to Flood & Drain systems

The flooding action helps prevent salt build-up in the root zone and achieves uniform root zone pH and conductivity.

Flooding purges stale (oxygen deficient) air from the root zone. Drainage draws fresh air back into the medium.

Flooding can enhance the penetration of disinfectants throughout the root zone.

Disadvantages to Flood & Drain systems

If no medium is used, pump failure can result in plant death within a few hours, especially in hot weather.

- Nutrient film technique (NFT) NFT provides no medium support for roots.

Typically, roots sit in a long sloping irrigation channel.

Nutrient is introduced at the high end of the channel and allowed to flow over the roots after which it drains into a nutrient reservoir. It is then

re-pumped back into the channel to repeat the watering process.

This feed cycle can be intermittent or continuous.

Basic design requirements for NFT are:

Channels need suitable slope for drainage (i.e. gradient 1:40).

Channels must be wide and deep enough to comfortably accommodate the plants mature root system.

Undersized channels can become choked with roots which can lead to damming, overflowing or create stagnant areas that fail to drain fully.

The last plant should be positioned well upstream of the drains outlet so that roots do not block the drain.

Growth problems can occur as the channel length increases. Plants at the head of these long channels often perform better than those at the outlet end.

The threshold length will depend on factors such as the type of plant being grown and the nutrient strength.

Advantages to NFT

Lower water and nutrient consumption.

Avoids the supply, disposal and cost problems associated with media based systems.

Relatively easy to disinfect roots and hardware compared to other system types.

The absence of medium makes it easy to inspect roots for signs of disease, feed adequacy, etc.

Regular feeding (and associated flushing) prevents localised salt build-up in the root zone and maintains uniform root zone pH and conductivity.

Environmentally friendly, minimal potential for localised groundwater contamination.

Disadvantages to NFT

Pump failure can result in plant death within a few hours, especially

in hot weather.

Not suitable for plants with large tap-root systems (e.g. carrots).

Compared to run-to-waste systems, it is less suitable for saline (salty) waters because the salinity of the recirculating water gradually increases.

Support beds structure

Nutrition

The grower has the complete control over the implementation of various types of fertiliser including the type, concentration and the pH of the nutrient solution.

The pH , temperature and EC/CF of the nutrient solution should be monitored, and the solution should be replaced to ensure successful hydroponic production.

Pests

It is commonly assumed that hydroponic agriculture systems are relatively free of insect pests and plant

diseases because the technology is mostly enclosed.

this is not true.

Pest populations can increase with alarming speed in greenhouses because of the lack of natural

environmental checks.

Check foliage and roots regularly for signs of pests (and diseases). Problems can multiply rapidly if left

unattended

Whiteflies: There are about 1,200 different species of whiteflies. They are pests in

many important agricultural and horticultural crops, both inside and outside the greenhouse environment.

Spider mites (2 spotted mite): Tiny spiders appear on the plant as pinhead sized yellowish spots. They feed

on sap and their presence is indicated by plants generally looking sick. They cause mottling of leaves that eventually turn brown and fall off. The formation of tiny webs indicates the problem is well advanced.

Aphids:

Pear shaped body typically ~2mm long; can be any colour. They suck sap from leaves causing leaves to curl.

Thrips Appear 1-3mm long with hairy wings. They feed off plant sap causing

damage to manifest as patches or streaks on the leaves.

Scales Brown, oval and hard-bodied. They suck sap from leaves and stems.

Thank you!

Glossary - CFL: Acronym for "compact fluorescent.- Chlorosis: The yellowing or whitening of normally green plant tissue because of a decreased amount of

chlorophyll CO2: Chemical symbol for carbon dioxide. - Conductivity: EC. - Ground water: Under-ground water deposit e.g. artesian bore. - Hardness (or hard). - HID: Acronym for "high intensity discharge lamp. - HPS: Acronym for "high pressure sodium" lamp. - Make-up water: Water used during the process of making a fresh batch of nutrient solution. - MH: Acronym for "metal halide" lamp. - Mottling: Spots or blotches of different shades or colours commonly found on leaves. - mS: Short-hand representation of "mS/cm". - Natural water: Water supply that is uncontaminated by pollution. - Necrosis: Death of plant cells resulting in dead/brown spots on foliage. - NFT: Acronym for "nutrient film technique". - Nutrient solution: The diluted nutrient that is fed to plants. It is usually comprised of a nutrient

concentrate, water and nutrient additives. For the purpose of clarity, the nutrient solution is sometimes referred to as the "working nutrient solution".

- O2: Chemical symbol for oxygen. - Oxidizing agents: For the purpose of this book, this term is used to describe substances

which attack organic material such as bacteria and viruses. - PGR: Acronym for "plant growth regulator". - ppm: Acronym for "parts per million. ppm has the same meaning or numerical value as

mg/L. - Precipitate (or precipitation): Insoluble solid deposit that forms within a nutrient solution

or water which eventually sinks to bottom of reservoir or adheres to sidewalls. - Recirculating nutrient (or recirculating system): The process (or system) where the

working nutrient solution is recirculated. - Respiration (or respire). - RH: Acronym for "relative humidity". - RO: Acronym for "reverse osmosis". - Run-to-waste: Type of growing system or method. - Saline (or salinity / salty): A water that contains excessive salt levels - usually sodium

chloride. - Scheme water: Water supply provided by a local authority. - Surface water: Above-ground water deposit e.g. river, stream, lake, dam, soak. - TDS: Acronym for "total dissolved salts". - Top-up water: Extra water added to a nutrient solution to increase the dilution factor or

maintain a desired level. - Transpiration (or transpire) - Wilt (or wilting): The drying out, drooping, and withering of the leaves of a plant due to

inadequate water supply, excessive transpiration, or vascular disease. - Working nutrient solution: See "nutrient solution".