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LECTURER: Good morning Annie, Tony. How are you?
ANNIE: Fine, thanks.
LECTURER: Well, tell me what you have here.
ANNIE: We thought we’d look at different methods of hydro culture.
LECTURER: Uh huh.
TONY: In the true hydroponics method the roots are bathed with water and nutrient solution while support for the plant must be provided above the container.
LECTURER: And...alternatively?
ANNIE: Alternatively, the plants can grow with their roots in a substratum such as sand, vermiculite or LECA granules.
TONY: LECA stands for Lightweight Expanded Clay Aggregate and vermiculite is...
LECTURER: Thank you Tony, I know what vermiculite is...but you should be prepared to give details about all these things to the visitors. Can you explain what the advantage of LECA is over traditional soil?
TONY: It’s a natural product...manufactured from clay...it’s colorful, lightweight and...perfect for allergy sufferers.
LECTURER: That’s right. Now tell me why.
ANNIE: Because it’s clean and hygienic, bacteria and soil diseases don’t get a chance.
LECTURER: Well, you could say that on this chart here..."Ideal for household plants".
ANNIE: And we’ll point out that the growing medium itself makes no contribution to feeding, which is provided in solution with the water.
LECTURER: Good, now tell me what you’ve got here.
ANNIE: This is a simple version of the first method, using a wide-necked jar which we’ve filled with water and nutrients, leaving space at the top. As the roots need to be in darkness we’ll cover the sides of the glass with brown paper later.
LECTURER: How did you get the plant through the cork?
TONY: We made a hole through the centre and cut the cork in haft so we could fit it around the plant stem and we padded the hole with cotton wool.
LECTURER: That’s a good demonstration of the principle involved, and ideal for a house plant but many people will want to see a wider application—what about more plants?
ANNIE: We haven’t quite finished the preparation yet, but over here you can see a bigger container in fact, any wide container can be used—with the nutrient solution in the bottom, air space above...and then we’ve made a rigid lid and we’ve covered that with a layer of litter.
LECTURER: What have you used for litter?
ANNIE: We’ve used wood shavings...
LECTURER: Untreated?
ANNIE: Definitely. That’s most important—you can use a variety of materials for litter but obviously nothing toxic and treated timber contains some nasty chemicals so, if you’re using sawdust or wood shavings, they have to be from natural timber.
LECTURER: A good point...
TONY: Yes, we’ll make a note of that when we list possible ingredients for litter.
LECTURER: Be sure to explain the purpose of the rigid lid—it’s wire mesh, isn’t it?—and why the litter layer is important too.
ANNIE: Well, the mesh is just a platform to keep the litter out of the water and the primary function of the litter is to exclude light from the root space...