Just harvested my first grow and my second is underway. By far, the hardest part for me has been figuring out how much to water each time. I was using Pro Mix HP Mycorrhizae in 5 gallon plastic pots, Medi One 4-3-3 nutrients and pHing my water between 6 and 6.3. I thought that I finally got my watering right – only watering when pots felt light and top inch of soil was dry. I also watered in smaller amounts, generally every two or three days depending on how the pots felt.
This worked really well until about halfway into flower, the tips of my leaves were burning due to nitrogen toxicity. From my research it seemed that since I never flushed (watered til runoff), excess nutrients built up in the soil causing nutrient burn. I proceeded to water til runoff, and that seemed to fix the nitrogen toxicity.
However, this required giving the plant a lot more water than I had ever given it, and it ended up taking 10 days for the pot to fully dry. I had basically over-watered it. My question is, how do I flush my plant without over watering it?
I’m on my second grow now and I’m still using Pro Mix, but this time I switched to a 5 gallon smart pot, as I read they dry faster. This time I’ve been measuring out my water each time, starting with just misting the soil in early seedling stage, then 50 ml for its first real watering, steadily raising the amount of water about 10-20% every second or third watering.
If it takes a little longer to dry out, I dial the amount back or wait longer to increase it. This has worked really well and I haven’t over watered a single time this grow. I’m guessing that eventually as I keep increasing the amount of water I will get runoff. But I am already on day 56 of my grow (day 16 of flower or day 8 if you count from the first pistils showing), and am still no where near to fully saturating the pot. I’m currently at 1.2 liters of water which will dry up in around 2-3 days.
I’ve read countless forum posts and everyone seems to water until runoff, even in the veg stage. I feel like I’m crazy, cause I’m in flower and feel like if I watered til runoff right now my plant would take at least a week to dry out, and maybe longer. How is everyone else watering til runoff (even in pro mix) and I’m unable to without severely over watering my plants?I’ve read countless forum posts and everyone seems to water until runoff, even in the veg stage. I feel like I’m crazy, cause I’m in flower and feel like if I watered till runoff right now my plant would take at least a week to dry out, and maybe longer. How is everyone else watering til runoff (even in pro mix) and I’m unable to without severely over watering my plants?
Thanks guys. I love the show and have been watching regularly since finding it.
If you want your pots to dry faster so you can feed more often then, you’ll need better drainage. With your soil, you should water about every 3 days with adequate runoff. It shouldn’t matter how much you water in during each interval with proper drainage.
I didn’t know you had to add anything to pro mix for drainage. It even boasts a “superior drainage capacity” on their site. It’s too late for this grow, but what would I add to pro- mix in the future so it has adequate drainage?
More perlite, crushed lava rock and/or some rice hulls are excellent options.
Thanks for the recommendations. I’ll try adding more drainage in my next grow. Unfortunately I bought a whole bale of promix so I’m stuck with that for the foreseeable future. Only growing a few plants so I have a shit load of the stuff.
Like Jmystro mentioned you are waiting to water due to water holding capacity of peat. If you mixed in coco and perlite you could water more often. When the medium barely holds any water (true soilless coco) you are watering all the time and roots die if you skip a watering. The runoff in this style is to remove the salts that dry and get stuck in the medium. Your mix won’t have that ability and the runoff is more to insure you don’t have any dry spots. Just adding a plain watering with some enzymes or fulvic acid will help get rid of extra nutrients. Possibly the pot is too large for the root ball?
So you are saying salt buildup isn’t a thing in pro mix? I don’t really need to water till runoff to get rid of excess nutes, just water more without nutes till signs of nitrogen toxicity subside? If true, that makes a lot of sense, and I think what I’m doing now is fine: just slowly increasing the amount of water I give it each time?
Always water to run off using salt based nutes. Just water less often and maybe have plain water only days. You can add Recharge on the water only days. Like feed, feed, plain water with Recharge cycles.
I’m already watering every 2nd or 3rd day, nutes one feeding and two feedings of plain 6.0 pH water. Maybe I need to water every 3rd to 4th day… Wish I could add recharge but I live in Canada.
Also medi one is organic, so doesn’t that mean it’s not salt based?
It doesn’t matter where the plant available ions came from. Whether from organic or synthetic sources, they are no longer “organic” in plant available form. Plant roots do not uptake organic elements through ion exchange. Once in their ion form, they can build up or bond in a medium. Medi One is derived from organic sources but does not contain any organic matter in the bottle.
Was just saying it’s not drying out creating salt crystals like mediums that hold more air then water. You are definitely getting a nutrient buildup and possibly even nutrient ratio imbalances. They are just staying more soluble and not as much in the salty crystal form like coco or even like the side of fabric pot (white crust) like your favorite baseball hat gets. Also peat has the ability to hold onto nutrients itself. High cec (holds ammonia nitrogen and other cations) while coco just holds water and small amounts of calcium, magnesium, chlorine, sodium, or potassium just depending on what’s available.
No-one has touched on watering and rooting out a pot so i will.
In veg you most likely start iff in a cup of some kind being either seed or clone. Its at this stage you should be watering til run off. And we transplant from cup to a one gal to a 3 gal to a5 gal. We do this to make sure ee get those roots going. Water til run off and when they dry out in 3 days or less transplant to the next size.
Once in your 5 gal and still in veg continue to water til run off and when those 5 gals dry out in 3 days the roots are well established and mow its time to flower.
Always massage your roots to loosen them up during transplant. Water more towards the edges of the pots and not so much the middle when trying to get a pot rooted out.
If you soak your pots in flower and they take 10 days to dry out its because the roots aren’t established.
Yeah, I thought re-potting a lot was bad and could cause stress. I’ve been planting in solo cups and then replanting into 5 gallon pots. Maybe I need to work my way up more as you say. I feel like my roots are not growing fast enough in veg… Like by the time they are ready to transfer from solo cups to a one gal (as you suggest) it is already almost time to flower and thus I want them in their final pot (which I thought was a five gal).
When people say “water to runoff” they are assuming you have good drainage.
Type of pot and other factors can make a really big difference. A fabric pot with great drainage will behave a lot differently than a plastic pot with small drainage holes. Also make sure you aren’t letting your plant sit in water. Sitting in a puddle is no bueno.
Straight peat holds a lot of water and can be pretty easy to over water if you aren’t used to it. If you are having a tough time getting watering right, I would consider switching to a coco based grow style in fabric pots. Coco in a fabric pot is almost impossible to overwater, as long as you don’t leave it sitting in a puddle.
I’m never letting my pot sit in water cause it never requires enough water to reach runoff. But I think that’s part of what you are saying; I need more drainage so I can achieve runoff without over-watering.
Coco almost seems like the opposite of my problem, where you have to water really often.
What is your soil pH?
I water with 6.0 ph and the few times I have watered till runoff, my runoff water was also 6.0 PH. I do not currently have other means of measuring soil ph other than measuring runoff.
I grow in peat. Water the outside couple inches to runoff and nevermind the center of the pot. Don’t let it dry out too much, peat is a bitch when it’s dry and you’ll be fighting against yourself.
I am going to try that next watering! Thanks.
Doppelgänger!