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Beaucoup

Wet Dry Cycle

18 posts in this topic

What are people doing with this?

I have just started growing with soil, using biobizz all mix.

I flowered some Black Jack autos and I now have some Whiteberry in veg, after 8 weeks from showing there is one plant at 90cm tall, one at 80cm and two smaller ones, at about 50cm and 60cm.

This morning the large plant had dried out completely, was looking a little droopy, and she drank 3lts of water with 1ml per litre of biogrow. The other plants were sitting in pots still a little heavy with water and looked healthy so I will water them another day.....

I am not worried about the 4 Whiteberry being different sizes, when I switch the lighting cycle in a week or so I can bend the taller plant and I have the two smaller raised up anyway, so I can get a canopy going.

My question is, with organic growing, do you need to let the pot dry out completely before watering again?

I understand the organic nutes are not absorbed by the plant right after watering but only when the pot has dried out a bit. How dry does the pot have to be before you should water the plant...

....I am thinking just letting each plant individually dry out until it looks thirsty then giving it water and nutes.

I am used to growing in canna, where it is wet all the time, but that seemed to be contributing to some kind of fungus in my tent, which eventually gave the plants stem rot. With growing in soil the problem is manageable, I think because the fungus cannot survive a long enough dry cycle....

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I think the ideal is last 10% water in the pots, then water, dont think its a good idea to be letting them dry out completely all the time, you might damage the roots if totally dry.

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+1 @@Smurfy..

it's best not to let them dry out completely as the compost will shrink round the edges of your pots,which will make watering them very difficult as the water will just piss down the gaps...and letting them dry out completely could(as smurfy says)damage your roots.

:hippy:

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Thanks guys.

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I sit my plants on deep dishes or plastic plates, I pour the water in letting it come out the bottom, it soaks back up very quickly,

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I judge watering time more by the posture of the leaves, pointing up or down then by the weight of the pot, uneasy to gauge.

Dont let them dry too much...

It takes time and 'doigté', even some gardeners intuition and feeling, to really get the perfect watering cycle.

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wet dry cycle is for to help noobs out so they don't over water them like pier says once you been growing a while you can tell by the look of the plant plus the way the foliage is looking ie if the leafs are perky and pointing out or upwards and the pot is still wet I leave them as this is ideal if the pots are soaking and the foliage is all droopy then they over watered and if the foliage is all droopy and pot is dry then they need watered practice makes perfection more the times you water and grow you will get the hang of it building up a solid root mass in the pots ie by potting up correctly makes watering and looking after them a whole lot easier imo. :haveadab:

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wet dry cycle is for to help noobs out so they don't over water them like pier says once you been growing a while you can tell by the look of the plant plus the way the foliage is looking ie if the leafs are perky and pointing out or upwards and the pot is still wet I leave them as this is ideal if the pots are soaking and the foliage is all droopy then they over watered and if the foliage is all droopy and pot is dry then they need watered practice makes perfection more the times you water and grow you will get the hang of it building up a solid root mass in the pots ie by potting up correctly makes watering and looking after them a whole lot easier imo. :haveadab:

viva ,ive been doing this practice and works perfectly but it is a bloody night mare if you have different strains lol lol,im in there every day and some days twice,its keeping them moist that im having trouble with.

Edited by pingpong
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always make sure they sit in some run off and leave for few hours if they drink it up then they might want more if. they sit in it then they have plenty and the pot will be totally saturetaed

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I use a moisture tester it's a doddle

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viva ,ive been doing this practice and works perfectly but it is a bloody night mare if you have different strains lol lol,im in there every day and some days twice,its keeping them moist that im having trouble with.

This is it, because my plants are different sizes they drink at different rates.

They do need checking every day but with only four plants it is not too much of a problem. They are all the same strain, which I have grown before, so I know what they are likely to do, how to bend them and when they are looking healthy.. ....

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I use a moisture tester it's a doddle

I've not got the wet dry cycle during the vegging stage down myself either, I seem to always leave it about a day too long, I should really invest in one or two of those sensors, what you pay for yours? Greens has got them at £25.

Here's some information you should find helpful.

Moisture and conductivity

Whether you're growing hydro or in soil, the electrical conductivity (EC) and moisture of your medium are two key elements that should be manipulated to meet your needs. Both of these factors are controlling the same thing; the ability of a plant to uptake water and nutrients from the growth medium. (EC measures the level of fertilizer salts in the water.)

A plant grows by first dividing cells then expanding them, and in order to do this it requires water. By limiting the amount of water available to a plant you limit the expansion of cells. This can work for you by keeping your internodes close together, or against you by limiting bud growth. Both the amount of water you give your plants and the EC at which you grow them control the uptake of water.

A plant's roots act much like a pump, using osmotic pressure to move water into the plant. In order for this to work there must be a larger concentration of fertilizer salts in the plant's roots than in the soil or hydroponic solution, so when the medium's level of salt rises above the roots', the plant will wilt. Raising the salt level in the medium closer to that which is in the roots limits the water availability just the same as if we had provided less water.

During the vegetative stage we want our plants to form very tight internodes, especially under artificial lighting. By allowing the EC to drop below ideal during this stage we are wasting valuable space growing stem instead of bud. Most marijuana strains are happiest when grown at an EC of between 1.5 and 1.8, but different strains have different preferences. Try growing one of your plants using straight water for a week or so, you will see the internode length stretch dramatically compared to the ones on a regular fertilizer regime.

1536-concan4.jpgexamples of long internodes (closeup)

Hydroponic tomato growers sometimes will grow their transplants at extremely high EC's (up to 6 EC!) in order to get really nice stocky production plants. Please note that when doing this they use special nutrient formulas designed for this purpose, most of which have potassium to nitrogen ratios of 4:1, much higher than normal, as too much nitrate at this high an EC will easily damage a plant.

(Try this formula if you're interested: calcium nitrate 7 grams, potassium nitrate 0.095 grams, potassium sulphate 9.25 grams, mono potassium phosphate 2.2 gram, magnesium sulphate 5 grams, micromix .02 grams. Slowly raise your EC during veg stage, I would not recommend going above 3 or 4 EC. This is experimental! Do not try on all of your plants at once until you are sure your strain can handle it. All of these ingredients should be available at your local hydroponics store, it is usually called "six pack formula". Be sure to bring your EC back down once you enter floral stage, by the time tufts of pistils are visible you want to be at your ideal EC of 1.5-1.8.)

Try not to change the EC too quickly as a sharp drop can cause root damage. This also goes during your final flushing period when you want to eliminate all fertilizer from the medium – lower the EC over a couple of days, as the sudden change in salt level will harm the roots.

When growing hydroponically, the only way of manipulating water availability is with the EC, while in soil we may also use the moisture level of the medium to the same ends. Many growers are under the mistaken impression that the EC and pH of their nutrient solution remains the same when applied to the soil. This in not the case, and you must test the soil in order to have a true

picture.

1536-concan5.jpgexamples of tight internodes (closeup)

To test your soil, take a sample from the center of the root zone at the side of the pot (don't worry the torn roots will be fine). Mix the soil with 2 equal parts distilled water and let sit for 20 minutes. Once the time is up take an EC reading and multiply this number by 2.4 (this takes into account the dilution and the pore space factor) this will give you an accurate picture of the EC the roots are actually being exposed to. The pH should also be checked at this time. It is not feasible in soil to maintain an exact EC at all times, what we need to try and avoid is EC's climbing much above what we want and plants going for long periods with very low EC's.

A frequent mistake marijuana growers make is over-emphasizing the need for a plant grown in soil to dry out completely between waterings. Cannabis does like dry feet but this simply means that the root zone must not be kept extremely wet at all times. Keep in mind that if the soil has an EC of 1.8 and then dries out completely the amount of salt remains the same, causing the EC to double or more.

As a general rule, during the vegetative stage you should keep your plants a little on the drier side as this will restrict cell elongation, creating a shorter noded plant structure capable of creating a dense bud cluster in the floral stage. (Unless of course you are using the high EC method described above, in this case you must not let your soil get too dry because of the increased fertilizer level you will create.) Maintain this level of moisture into the first 14 to 20 days of 12/12 to minimize internode stretch.

As soon as early flowering begins you need to increase soil moisture to a nice evenly moist (not soaked) level to maximize bud expansion. Growing marijuana too dry during this stage will adversely affect your overall yield, as will having too high an EC in the medium.

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Invest in some capillary matting. I have my plants sitting in a large tray, the matting holds an extra 6 litres of water that the plants can suck up as and when they need it. The matting also equalises the amount of water taken up by each plant after watering. It also means you can water less frequently too. My plants have never looked so healthy!

Edited by Hot_Rock
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I've not got the wet dry cycle during the vegging stage down myself either, I seem to always leave it about a day too long, I should really invest in one or two of those sensors, what you pay for yours? Greens has got them at £25.

Here's some information you should find helpful.

£6 from that garden centre diy place or you can get £1 LED ones from the pound shop

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I tend to check the top inch once thats dusty then I water. You can damage the root system by allowing it to dry too much and you want to avoid that really. Especailly when plants are 6-8 weeks (maturing) and of large size relative to the pot I lie on the side of slightly too wet than dry myself.

i think the wet/dry cycle is quite a fine line thing, too dry and risk root damage and too wet and get humidity related problems. Watering schedule will relate to your pot size/plant size and growing conditions.

Edited by MaxTrichomes
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