Effects of color spectrums on plant growth
16 years ago indoor growbox, LEDs, spectograph
I have written about the importance of lumens when growing indoors but the intensity of the light at specific wavelengths can be over even more important. NASA has done some significant research on the subject to determine the possibility of growing leafy vegetables on a trip to Mars using as little electricity as possible to get the most benefit out of every watt. In space any wasted energy (heat or light not used by plant growth needs to be severely limited.
It should not be a surprise that using LEDs is part of the solution they came up with since they use 20-30% of the energy of a comparable HPS (High Pressure Sodium) bulb which is considered very efficient given the lumen output per watt. The most interesting part of their findings was how specific red and blue wavelengths were imperative to the growth of plants and actually could sustain growth with just these limited wavelengths. Given the freezing temperatures and masses of snow on the ground the best use of this information for indoor gardening and specifically my $20 PC Grow Box. Understanding the wavelengths that your artificial lights creates can help you have increased plant growth and save on your electricity bill at the same time.
When evaluating which light you must consider wavelength and also the intensity of the light at that wavelength. A tool to do exactly this is a spectrograph, which you can purchase, make your own (this was a fun project with the kids), or just trust other peoples readings. I chose made my own, but am displaying results (led museum) since I would have to estimate the intensity based on the brightness of the spectrum created which would lack some accuracy.
Just to get some perspective, this is what how various light sources appear to a spectrograph:
| Sunlight |  |
| Florescent Bulb |  |
| Incandescent bulb |  |
| Low power blue LED (5mm) |  |
| Low power red LED (5mm) |  |
| Low power white LED |  |
As you can see incandescent appears to be the closest to matching the wavelengths and intensities of sunlight though it we need to remember that the orange/yellow/green wavelengths provide essentially are wasted from the plant’s perspective due to natural reflection of these colors. So if a light looks bright to you, there is a good chance you are wasting electricity, as humans our eyes respond well to these wavelengths why we will find these bulbs to be much “brighter” from our perspective. The fluorescent bulb is a good example where we see this light as bright for plants other than the small slices spectrum much of the light is unusable. I have had good luck growing indoors with CFLs along with incandescent, but from the information above I my results cold have less spectacular if hadn’t included the incandescent bulb. At the time the only reason I used it was to generate a little extra heat on some of the cold nights.
The key point is I could easily have much better results using significantly less power. According to NASA’s research the most efficient configuration is to only have red/blue LEDs consisting primarily of red (80-85%) with the remaining (15-20%) being blue LEDs. I would recommend replacing the some of the of the blue LEDs with white LEDs to provide a full spectrum including a pretty intensive blue spectrum in itself. As an added bonus this will provide some “human” light in orange/yellow/green spectrum to allow us humans to view plants with less strain.
By replacing the two 24 watt CFL and one 80 watt incandescent bulb with a few hundred LEDs I could drop at least 124 watts with my new configuration. Assuming I am running my grow box every day for 14 hours a day this could save me over $45 a year as well as just being the more environmentally conscious thing to do.
So during these cold winter months if you grow indoors whether just for seedlings or vegetables all year round be sure to remember that not all indoor lights are created equal.
Tags: cheap, garden seeds, grow lights, growbox, led, outdoor plants, vegetables
Broto Domestic Greenhouse grows plants through aeroponics
16 years ago aeroponics, hydroponics, indoor growbox
If you want something that is a little more aesthetically pleasing than the $20 PC Grow box and don’t have the counter space for an AeroGarden then the Broto Domestic Greenhouse might be the right option for you. Information such as price and if it will actually be commercially available seem to be missing, but seems to be a completely self contained aeroponics solution and given the use of LEDs for lighting I would imagine it would be a fairly low power consumer.
Tags: cheap, growbox, led, outdoor plants, vegetables
Butterfly Garden Update (Nasturtiums and Marigolds)
16.5 years ago butterfly, butterfly garden
My black-eyed susans and purple cone flowers didn’t survive being transplanted after being moved from the PC Grow Box, but the Nasturtiums and Marigolds are doing just fine. Even have had some sightings of a few butterflies unfortunately none have stuck around long enough to get a photo, guess there is still lots of summer left this year.
Read Other Butterfly Garden Posts
Tags: butterfly garden, cheap, growbox, outdoor plants, vegetables
How to save onion seeds from the garden
16.5 years ago onions, seed saving, seed storing
In the past I have harvested seeds for cilantro which worked so well I have decided to try more this year. Now my gigantic onions are producing seed stalks and umbels are beginning to open seems like a good time to try harvesting my own onion seeds.
To save these seeds it is pretty simple, when the umbels have dried out and begin to open. At this time carefully cut them off (making sure that seeds do not fall) and place in a them in a cool dry location for 2-3 weeks. I prefer to put my harvest seeds in the refrigerator in a paper bag. It is a good idea for onions to cross pollinate so I will plan on buying some other onion seeds to mix with the ones I am harvesting to allow for cross pollination.
Onions take 100-120 days from seed to maturity, if you start from sets which you grow from the previous year can shave 3-4 weeks off that time. I could make my own onion sets by planting 30-40 seeds in a square foot area during late summer. After two months rake over the tops and let them turn brown and dry out then store them in a dry place until next spring.
My PC grow box will be empty 10 weeks before my last frost date so planning on starting my onion seeds in there moving them outside 4 weeks before the last frost.
If you want to learn more about saving seeds for onions or other vegetables be sure to check out International Seed Saving Institute which has great advice about saving seeds from dozens of different plants.
Tags: cheap, cilantro, garden seeds, growbox, outdoor plants, vegetables
Oh the carnage…
16.7 years ago indoor seed starting, tomato
I am sorry to inform you that we have had a death in the garden. By entering this world a just a little sprout started from a packet of seeds just a couple of months ago. They spent most of their life being nurtured in the comfortable surroundings of the PC grow box our poor tomoto plants did not survive the harshness freakish winter storm we which occurred weeks after our supposed last frost date. On the positive side all of our cold season crops (garlic, onions, cilantro, lettuce, peas) as well as the corn and butterfly garden flowers have endured and enjoyed cozying up with the snow and are doing just fine.
Tags: butterfly garden, cheap, cilantro, garden seeds, garlic bulbs, growbox, outdoor plants, tomato plants, vegetables
Average last frost dates are only right half of the time
16.8 years ago indoor growbox, indoor seed starting, spring, tomato
Our last frost date in my area should have been March 24th but given the frosty mornings this past week and the fact we had snow coming down most of today it looks like this year our last frost date will fall on the other side of the bell curve. Unfortunately, I was optimistic with some of the great weather we were having earlier and planted my tomato seeds for a much earlier move outside. The poor tomatoes are still growing in my PC grow box but starting to not look so good. As you can see from the picture below my tomato plants are in some dire need of some non-artificial light. I am afraid I might end up buying my tomato plants at my local nursery (yet again) this year. Vegetable gardening is definitely one of those hobbies which it does not pay to be a too optimistic.
Tags: cheap, garden seeds, growbox, outdoor plants, tomato plants, vegetables
