wegster Posted September 28, 2002 Share Posted September 28, 2002 I'm on my first grow with a NFT400 system and have just transplanted my seedlings into 3" rockwool cubes. I've just realised that I used Ionic Bloom instead of Grow when I soaked the cubes. Can I leave the seedlings with this mix or should I prepare a fresh batch of cubes? Also I am planning to build a tent based on highlanders example and was wondering on how many sq foot I should go for based on my 400w HPS lamp. Advice seems to vary between 30-60watt per sq foot. Any advice very much appreciated. Cheers. Wegster Link to comment Share on other sites More sharing options...
mr beaner Posted October 3, 2002 Share Posted October 3, 2002 Hi mate Suggestion re: the rockwool - pour a litre or two of plain water (pH'd to 5.8) through each cube until the runoff has a low ec/cf/ppm reading (close to that of the plain water). Then just add the correct nute solution to the tank and run as normal (or pour directly on the cubes if they're not yet in the tank). Should work. One thing though - you say that you are using seedlings. I would strongly advise sexing them and using female clones only in the tank. If you get a male plant or two in a tray it will be a complete bitch to remove, as well as reducing your yield quite a lot. As for watts psf, 50w is a good figure to be working with. A bit of fluctuation either side isn't going to hurt (40-60w), but outside of this range you will either suffer from smaller less potent bud or the return will not rise in proportion to the electricity used. Higher watts can also cause heat problems. 50 will be fine. Get your lamp as close as possible to the plants (have a well vented grow room and use a vented reflector if you can) to maximise the PAR watts hitting the plant. PAR = photosynthetically active radiation, that part of the light spectrum used by plants. Most HPS/MH bulbs are rated in lumens (light visible to the human eye). However, there is a close correlation between PAR intensity and lumens, so a high lumen output HPS lamp will also be putting out a healthy dose of PAR watts. Hope that helps you a bit, good luck Link to comment Share on other sites More sharing options...
wegster Posted October 3, 2002 Author Share Posted October 3, 2002 Hi Mr Beaner. Thanks for your reply - very helpful. I've flushed the rockwool through as you suggested - hopefully no damage done + will aim for 50w sq foot on the lighting front. One thing I probably mislead you on was that the seedlings are not yet in the gro tank as only about 4" tall at the moment, and are under fluoro's. I intend transferring them when they get to about 12". One question - I only have seeds as this is my first grow so how do I sex them before I transfer them into the tank as they will still be vegging? Sorry to be thick but i'm now a bit confused and I dont want a load of blokes in my tank that i'm not going to be able to remove! Thanks Wegster Link to comment Share on other sites More sharing options...
TrichomeUK Posted October 4, 2002 Share Posted October 4, 2002 wegster - that's the problem with growing seeds in NFT - you cannot sex them without ending up in a mess. Instead, you would be better to grow out seed plants in pots containing soil, or coco/perlite, etc., find the mother(s), clone and fill NFT. Link to comment Share on other sites More sharing options...
wegster Posted October 4, 2002 Author Share Posted October 4, 2002 Cheers for that Trichome - there's a bit more to this than I thought Another suggestion that has been put to me is to put the unsexed seedlings into the tank then cut the males near the bottom of the stem and remove the plant from the tank after sexing. Adding 'Cannazym' I have been told will prevent any problems with the roots rotting and causing problems to the remaining ladies. Anyone had any previous experience of this? Link to comment Share on other sites More sharing options...
TrichomeUK Posted October 5, 2002 Share Posted October 5, 2002 wegster, Ok, put it this way - if you want to grow properly, use pots with regular seed, if you want convenience, hydro them. I've done both, and pots are better. About Cannazym, I've never used it - most people inc. me use H202/Oxyplus instead (cannot be used together). Link to comment Share on other sites More sharing options...
mr beaner Posted October 24, 2002 Share Posted October 24, 2002 You could also take a cutting (3") from each of your unsexed plants when they are about 8" tall, put each cutting in a cup with a bit of water in it, place under a 12/12 lighting regime and within 1-2 weeks it should be showing enough flowers to determine the sex of each plant before you put them in the tray. Don't forget to change and top up the cup water regularly. When you've sussed out the females, take a cutting from each, root and keep on a vegging light cycle. When the seed grown plants have flowered, you will be able to select the best one as a mother for future cloning. And keep everything well labelled so you know what's what! B) Link to comment Share on other sites More sharing options...
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