RHP - Lightmix

A lightly pre-fertilised peat substrate of 50 litres carrying the RHP mark. A lightmix without a brand name, for growers who steer the feed themselves and would rather not pay for the label.

Working with a bag that does not print the figures

A branded substrate tells you what is in it: how much fertiliser per cubic metre, which pH, which EC. This bag does not, and saying so is more honest than inventing numbers we cannot support. What you do know is the category: a lightmix is lightly pre-fertilised, so there is enough in it for the first week or two and after that you steer.

In practice one action settles it. Water the first time with a known pH and catch what comes out of the bottom. Measure that. That single reading tells you more about this bag than a spec sheet would, because it is your water through your substrate. If the run-off sits near the EC of your feed water, the reserve is small and you start feeding soon. If it is clearly higher, you wait a while longer.

After that you grow on it as on any lightmix: small amounts, let the pot dry back a little in between, and feed to what the plant asks for rather than to a schedule written for a different bag.

What RHP does and does not tell you

The RHP mark is about the raw material: origin, purity and consistency from batch to batch. Free of weed seed, sand and pathogens, and next month's bag resembles this one. That is precisely where potting soil most often goes wrong, so it is a mark that means something.

What it does not tell you is how much feed is in there or what pH you are starting at. A mark about origin is not an analysis.

Technical Specifications:

• Type: lightly pre-fertilised peat substrate
• Certification: RHP
• Contents: 50 litre bag
• Feeding: start when your run-off reading calls for it, as a rule after a week or two
• Not stated: exact composition, pre-fertilisation, pH and EC are not published for this bag

Frequently asked questions

Why are there no pH and EC values here?
Because they are not published for this product. We would rather print nothing than another brand's values, which is what often happens with bags like this.

How do I know when to start feeding?
Measure your first run-off. If it sits close to the EC of your feed water, the reserve is as good as gone.

Can I compare this with a branded lightmix?
In design yes: both are lightly pre-fertilised peat. The difference is that with a branded bag you know exactly what you start with, and here you measure it once yourself.

What is this suitable for?
Seedlings, cuttings and young plants, and anyone running their own schedule from the start.