Plagron - Bat Guano

A powdered organic fertiliser based on guano, rich in phosphorus and potassium. You mix it through your substrate when potting up.

It is slow, so you mix it in before you need it

Guano is organically bound, which means the soil life has to get to it before the plant sees anything. Reckon on about a month between mixing it in and the point where it genuinely becomes available. That sounds like a drawback and is meant the other way round: you set it up for flowering while you are still potting, and after that you are not chasing it weekly.

The practical consequence is that the moment of mixing decides whether it works. Mix it in when you see flowering start and it arrives too late. Mix it in as you move the plant into its flowering pot and the release coincides with the period when the phosphorus and potassium are called for. Adding some mid-crop is possible, but the same wait applies again.

The 3-15-4 ratio shows what it is for. Little nitrogen, plenty of phosphorus: that is a flowering ratio, not a growth one.

What it fits, and what it does not

In a lean or lightly pre-fertilised bag there is room for it. In a heavily pre-fertilised substrate there is not: that is already rich, and you would be stacking two reserves on top of each other. Plagron name Lightmix and Promix as the mixes that suit this. The same principle holds for open ground, with the caveat that heavy clay calls for a complete mix rather than a powder.

Available sizes

Technical Specifications:

• Type: powdered organic fertiliser on a guano base
• Fertiliser type: organic NPK fertiliser 3-15-4
• Nitrogen: 3 percent total, entirely organically bound
• Phosphorus: 15 percent water-soluble phosphorus pentoxide
• Potassium: 4 percent water-soluble potassium oxide
• Dose: Plagron work to 2,5 to 5 percent of the substrate volume; follow the figure on your own pack
• Action: slow, reckon on about a month before it becomes available
• Mixing: evenly through the substrate, not as a layer against the stem

Frequently asked questions

My guano is brown rather than white, is that right?
Yes. Guano is a natural product and the colour depends on its origin and on the floor of the cave. Plagron confirm the current batch is brown and that the behaviour is unchanged.

Can I mix it through a full pre-fertilised bag?
Better not. That is already rich. A light mix or used potting soil is the place for it.

Why do I see nothing in the first few weeks?
Because it is organically bound and has to be broken down first. That is normal and not a sign anything is wrong.

Is this 100 percent bat manure?
We would not want to state that firmly. The listings differ: some name bat manure only, others also seabird guano and vinasse. What is settled is the NPK ratio and that the base is guano.