Tag Archives: fertilizers

Fertilizing AutoFlowers

In your book, Growing AutoFlowers second edition, you recommend that I start fertilizing with a 20-20-20 fertilizer and only use one fourth of the recommended dose.  Can I just use a 5-5-5 fertilizer instead?

— Duke in Idaho

Hello Duke.,

Thank you for your question. I’m sure this is a question people have as well.

Even though applying basic math makes it seem like using a 1/4 dose of 20-20-20 is equivalent to a 5-5-5, it is not true.  The fertilizer is still a 20-20-20 concentration, but you are using less of it.  When in doubt, it is better to UNDER fertilize AutoFlowers, rather than over fertilize.  You can always add a little more if needed, but it is hard to correct an over fertilizing problem.

If you decide to get a 5-5-5, you should still only use one quarter of the dose recommended on the packaging.

Best,

Dr. Grow