I've been growing for a while and have always heard that you veg with the MH bulb and flower with the HPS bulb. After running my veg room with a 400W MH set-up I realized that the hotter-running MH bulb was making my tiny veg room too hot. So I switched to a 400W HPS set-up in my veg room to keep the heat down. Now that it is cold outside I switched back to MH and took notes of the difference in the plants while vegging; HPS vs. MH. Here is some of what I noticed.
Seedlings vegging with the HPS bulb tend to grow straight up with long distances between the nodes. Because they shoot up so fast you often have to brace the young stems against a fall-over disaster. With the MH lamp seedlings grow their first couple sets of leaves a lot wider. It's not unusual to have a 4 inch plant that is 6-8 inches wide. Conclusion -- if you want bushy veg with MH.
Clones just going into dirt are not affected nearly as much by the HPS veg compared to how they grow while vegging with the MH. I did notice that I don't have to FIM or top my small indicas to make them bushy the way I like. With a usual topping at 6 inches tall my gals grow like a Christmas tree ( a good thing) under the HPS bulb but spread out so wide with the MH bulb that they are twice as wide as tall. That takes up too much room so I have quit topping early veggers with MH.
I haven't noticed any change in how fast the plants mature using each mode. Far as I can see the difference is mainly plant shape.
These are just my observations regarding my particular grow. I don't promise you will have the same results I did. Just throwing it out there.
Good luck, BigSteve.
Seedlings vegging with the HPS bulb tend to grow straight up with long distances between the nodes. Because they shoot up so fast you often have to brace the young stems against a fall-over disaster. With the MH lamp seedlings grow their first couple sets of leaves a lot wider. It's not unusual to have a 4 inch plant that is 6-8 inches wide. Conclusion -- if you want bushy veg with MH.
Clones just going into dirt are not affected nearly as much by the HPS veg compared to how they grow while vegging with the MH. I did notice that I don't have to FIM or top my small indicas to make them bushy the way I like. With a usual topping at 6 inches tall my gals grow like a Christmas tree ( a good thing) under the HPS bulb but spread out so wide with the MH bulb that they are twice as wide as tall. That takes up too much room so I have quit topping early veggers with MH.
I haven't noticed any change in how fast the plants mature using each mode. Far as I can see the difference is mainly plant shape.
These are just my observations regarding my particular grow. I don't promise you will have the same results I did. Just throwing it out there.
Good luck, BigSteve.
