Trying to decide...

7 years ago

Hi - I'm about to take the plunge and buy grow lights for my first attempt at growing from seed. Can't wait! After a lot of research (thank you all), I am very close:

I have two questions however:

1. Choosing a bulb size: I know I need roughly 6400-6500K.

But, what is the difference between T5, 8 and 12 bulbs?

My understanding is that the T8 are larger in diameter, (the T5s are next, and the skinniest are T12) but does that mean that T8 are preferable even if they are all the same K?

For example, I have an area that is only 12 deep (front to back). Would it be better to get a fixture that holds say, 4 T5s or one that holds 2 T8s? Does it matter?

2. Fixture Design: I'm a little confused: I understand that plants at the edges of the light can get leggy, so I want to make sure that the plants on the edges get enough light. With this in mind, I am looking at two types of lights:

https://www.amazon.com/gp/product/B002JQBQZQ/ref=ask_ql_qh_dp_hza

and

https://www.amazon.com/Light-4lamps-DL824-Fluorescent-Hydroponic/dp/B009GU4RMC/ref=sr_1_4_acs_osp_osp35-ad5950f1_cov_2?ie=UTF8&qid=1546800928&sr=8-4-acs&keywords=t5+grow+lights+2ft&tag=heavy0013-20&ascsubtag=ad5950f1-098b-46e9-80ff-73caf983423f&linkCode=oas&cv_ct_id=amzn1.osp.ad5950f1-098b-46e9-80ff-73caf983423f&cv_ct_pg=search&cv_ct_wn=osp-search&pd_rd_w=eS3Zh&pd_rd_wg=NQcYD&pd_rd_r=804d7fec-6f33-49eb-b58e-79e115b8c286&pf_rd_r=H88JFPQDFQG773YT19ZE&pf_rd_p=7f6b8bb9-631f-46f6-b8ad-496a9af123d5&creativeASIN=B009GU4RMC&pd_rd_r=804d7fec-6f33-49eb-b58e-79e115b8c286&pf_rd_r=H88JFPQDFQG773YT19ZE&pd_rd_w=eS3Zh&pd_rd_i=B009GU4RMC&pd_rd_wg=NQcYD&pf_rd_p=7f6b8bb9-631f-46f6-b8ad-496a9af123d5

(sorry for the long link).

This second one seems preferable because the hood extends out (left and right) thus reaching a little more area, in terms of growing. This said, the second one gets great reviews.

Thoughts? Other product suggestions?

Thank you so much!

Noel, Boston, MA

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Comments (7)

heidinoel
Original Author
7 years ago
Oh, I forgot to add, any fool-proof soil recommendations? Thanks,
Bruce (Vancouver Island)
7 years ago
The "T" number is the number of 1/8" increments in the bulb diameter - so a T5 is 5/8" diameter, T8 is 1" and T12 is 1-1/2" diameter. The size doesn't matter but the T5 bulbs are more efficient than the T8 or T12 bulbs. You should also look at LED bulbs which are made out of plastic rather than the standard fluorescent bulbs which are glass and contain mercury.

As well as a 6000-6500K temperature/colour bulb you also need about 4500 lumens of light in the fixture so you need to get as many bulbs as required to get the lumens.

The seedlings will get leggy if you have the lights too far away from them. The lights need to be within 2" of the seedlings when they first germinate. As the seedlings grow you can raise the lights to keep them just above the tops of the seedlings. You also need to run your lights for about 14-18 hours a day.

Hope this helps.
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heidinoel
Original Author
7 years ago
Hi and Thank you, Bruce. I feel so foolish not knowing that the T is the diameter! Good to know the T5s are more efficient. As for LEDs, are they more expensive over all? I just haven't found as many housings for LEDs as fluorescents. Do they come/are they measured in the same lumens (e.g 4500K, 6500K)?

Do you have any thoughts on the bulb fixtures/housing? I haven't seen as many LED ones.

Thank you!
Bruce (Vancouver Island)
7 years ago
Hey heidinoel - yes LEDs are more expensive but they last a lot longer - way better value in the long run. Watch this YouTube video - he explains absolutely everything you need to know.

https://www.youtube.com/watch?v=LHlDv5i2v1A&list=WL&index=7
User
7 years ago
Another recommendation for LEDs - they have come a long way in a short space of time...drawing far less energy from the grid and keeping thermal output low - criteria worth considering, especially for summer propagation.
heidinoel
Original Author
7 years ago
Thank you! Good to know. I'm going to look into them. Any tips on who sells good ones? (That is, in the US - it looks like you might be in/from New Zealand)?
xiangirl zone 4/5 Nebraska
7 years ago
When I used grow lights I had them hanging from hooks on the ceiling with thin ropes so I could control the distance from the light to the seedlings. Make a mental note to design something easy to adjust.