First feeding recommendations

My first grow in a long time so some experienced help much appreciated.

These are my girls on day 11 (1 Hulkberry, 1 Green Gelato, 1 White Widow). Growing in Pro Mix HP they have had 2 water only feedings and have developed a good root system but certainly not yet root bound. I am going with Green Planets Medi One nutrients. The chart says 1ml/litre for seedlings and cuttings but since this will be their first feeding should I cut that back to 25%, 50% or go full strength? Oh and before I get jumped on yes those are clear solo cups but they are inside coloured solos so I could pull the out and see the root development.

Go half strength, and work up from there. The companies that make the nutes don't know if you are growing, tomatoes, or weed, much less the specific strain.

Feed half strength, and let the soil get fairly dry between waterings. Best way I've found is to pick up the cups right after watering, and see how heavy they are. You'll definitely be able to tell when to water, based on how light the cups are. It's good to let the roots look for water. It promotes strong roots.

And, you've got a little ways to go before they are root bound, in those big cups.

Don't forget to balance your pH in the water, not the soil, before watering.

Thanks JS

Yes I’ve been letting the soil dry out judging by weight as you suggested. I will definitely ph my water before feeding.

Thought I would let them get at least 4 - 5 nodes before transplant.

Fortygrit said:

Thanks JS

Yes I’ve been letting the soil dry out judging by weight as you suggested. I will definitely ph my water before feeding.

Thought I would let them get at least 4 - 5 nodes before transplant.

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You bet. Most potting soil will have a couple weeks of fertilizer added in, so you may not even have to start feeding just yet.

Also, test your pH after adding nutes, as nutrients change the pH when added. You can get really cheap pH pens online for under $20, or you can get one of the test kits with the drops, as well as pH up, and pH down, which you'll need to adjust he pH level.

A broad reason why it's important to have the pH in range, is because it allows he plant to transport nutrients throughout itself.

Great info. I was not sure if the Pro mix being a soiless medium had any/enough nutrients to carry the seedlings much past 10 days or so.

I also wasn’t sure whether or not those cheap PH pens work well/accurate or not. Seems to be a lot of yay/nay info on that. Was going to purchase a decent one from Blue Lab if it’s worth the $100+. In the mean time I have a Salifert kit (drops) left over from my salt water aquarium days which is fairly accurate. Thanks for the chart and the optimum range. Is there an ideal PH. I’ve read anywhere from 5.8-6.5, and that may be strain dependent?

Fortygrit said:

Great info. I was not sure if the Pro mix being a soiless medium had any/enough nutrients to carry the seedlings much past 10 days or so.

I also wasn’t sure whether or not those cheap PH pens work well/accurate or not. Seems to be a lot of yay/nay info on that. Was going to purchase a decent one from Blue Lab if it’s worth the $100+. In the mean time I have a Salifert kit (drops) left over from my salt water aquarium days which is fairly accurate. Thanks for the chart and the optimum range. Is there an ideal PH. I’ve read anywhere from 5.8-6.5, and that may be strain dependent?

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If it's a soilless medium, it probably doesn't have any nutes. Sorry, thought you were soil.

Nah, you don't need a Blue Lab. I have an $18 pen that works fine. I just calibrate it each month, which is really easy, because it self calibrates. But, once you figure out what pH your tap is at, and how much your nutrients offset that pH, you won't have to test it every time. Just once in a while, to make sure you're on track. With that being said, I'd just get one of the droplette kits.

Also, for hydro, which soilless medium qualify as, your optimal pH is going to be 5.8 to 6.0.

I have a pen because I'm growing via RDWC.