Hot answers tagged

29

Plants need approximately the same wavebands of light that we humans see in; from violet to deep red, and on into the non-visible near infra-red (380 to 720ish nanometres - nm). Normal incandescent bulbs deliver much of this, although special bulbs for plant growth are better - different spectra affect different aspects of plan growth, e.g. blue light can ...


18

It would definitely depend on the plant species you are talking about. Some plants specifically thrive in continuous light. For example, in northern Alaska the day-night cycle can during the summer can become 19 hours of light (or more) and 5 hours of night. This allows people to grow giant cabbage (the record weighing approx. 127 lbs). Some plants ...


14

For many indoor tropical plants life in the office is slow death. You may feel that way yourself after a bad day! With minimal light levels and good watering practices most tropicals will live for a while. The ones that require high light will draw on their stored resources in the roots and gradually go downhill. Tropicals that tolerate low light levels for ...


11

A lot of research has been done on this and most of the results vary by species. Every plant has a photoperiod or the number of hours of light it is used to receiving in a day. Short day length plants can have stunted growth as they depend on day length to trigger flowering and fruit/seed production. Day neutral or 12 hour plants like most tropicals can do ...


10

My summary of the various information sources would go something like: Light outside the range 400 to 700 nm is less useful. As all the light shown below is in the 400-700 range you are not spoilt for choice. . All light in the range is useful but that in the middle may be somewhat less so that at the right hand end may perhaps be slightly more so ...


9

Lettuces don't need a lot of light to grow. I recently read "The Winter Harvest Handbook" by Elliot Coleman and in it he describes growing lettuces in the winter in Maine (Zone 5) in the dead of winter underneath two layers of insulating row cover. They don't grow fast as in summer, but they do grow. The nice thing about leaf crops (which lettuce is) as ...


9

Etiolation is long, spindly growth caused by poor lighting conditions. Plants will tend to be more yellowish because of chlorophyll lack. You will see it at its worst when trying to greenhouse start plants before you have enough sunlight to properly enable photosynthesis. The plants know they're light starved and are trying to grow tall enough to get it. ...


8

It's better to try and mimic nature where there is a continuous period of light followed by darkness. Some plants need a period of darkness like tomatoes and many flowering plants but other tropical plants are just fine with getting light twenty four hours a day. This photo, courtesy of @geermc4 shows what happens to tomatoes with different light periods ...


8

The reason you are not finding the answer you are looking for in regards to the lumen requirements of crops is that lumens is a measurement for humans. It is based on the level of light that we can perceive. Plants mostly require light in wavelengths of around 430,450,650,675 nano meters (depending on the crop), with highly varied intensity requirements ...


8

Try removing the bag a little at a time over the period of several days so the seedling can acclimate to the unprotected environment. It's going to be just like hardening off any plant.


8

The cost effective solution for quite some time is and has been and probably will be to move further "towards the equator" and ship "away from the equator", or for a few things that don't ship well and have adequate profit margin grow in a greenhouse, not a basement, sometimes with supplemental lighting. Basement growing tends to be concentrated on high-...


8

First, here is what sunburn looks like on an aloe leaf: And here is what etiolation looks like on an aloe (this one's actually mine :o): Mine is etiolated because it's in the basement under fluorescent lighting, which is on 24/7. That plus the warm temperatures are confusing to the plant. Mine responded by trying to grow (although I haven't watered it ...


8

The damaged leaves will not heal, and the weakened narrow portion of stem will remain that way. It can grow from the end, though, and that can be healthy. It was obviously suffering from etiolation. I think the best method of action starts with repotting the aloe. Use a free draining cactus mix, and a free draining pot. You can repot the pups in separate ...


7

Some seeds will germinate with just warmth and water but if they do not get sufficient light they become spindly and stretched out. These seedlings are weak stemmed and tough to plant out. You get better seedlings by growing them under light. Once they are around the two leaf or four leaf stage you can take the top off your tray and move them into indoor ...


7

You can probably get a number of fruiting plants to flower and set fruit once indoors. I have seen coffee plants, citrus and members of the fig family flower and set fruit or seed indoors under fluorescents. The problem is that flowering and fruiting takes a lot of energy. If the plant does not have more illumination than standard indoor light levels ...


7

Actually.. Here's a study that shows tomatoes do pretty well in a 24 hour continuous, but they varied the temperature and they didn't get the spotting that had occurred with 24h lighting in the past. Did better than the 16 hour light / 8 hour dark, anyways. http://hortsci.ashspublications.org/content/40/2/374.full.pdf


7

Moreover, in my biology courses, we learned how (most) plants have a two-phase cycle: an anaerobic one (i.e. “breathing” CO2) during the day, and an aerobic one (“breathing” O2) at night. Wrong. There are two main cycles of photosynthesis colloquially called light and dark cycles. The light cycle requires light. The dark cycle does not require dark. It ...


7

You could get multiple plants and rotate which one is in your office every few weeks, bringing one home on a Friday night and then the next one in on a Monday morning. Honestly I had no idea what kind of stress these changes would put on a plant compared to staying in the office full-time, but I suspect it would work.


7

I have had excellent indoor results with two T5 fluorescent tubes per 8 heads. The most important thing about the lights is that you must get 6400 Kelvin (+/- 300) wavelength lights. They are not the most common you will find. Place the lights about 10-20 cm from the plants (only do this with fluo or LED lights, not Metal Halide or HPS bulbs) When the ...


7

There is very little good information about the actual wavelength spectra and intensity for household LED bulbs and they may differ by model/brand and color temperature (ie. 3000K vs 5000K) to some degree. But if they are white (soft or bright) they do emit in RGB - Red Green and Blue. If it was too slanted toward blue (or another color) you would find ...


7

A 20,000°K lamp will have peak output at 145 nanometers (Wien's Displacement Law). That's hard ultraviolet. It will hurt your plants. 10,000°K still peaks at 290nm, UV. You want a lamp with a far redder color temperature. Here's a nice graph of the wavelengths plants like: See the page Light and Plants


6

You can use just about any light source but each has it's consequences for your design: fluorescent lights are cheap, have a long life, tubes are available to mimic sunlight and they don't generate a lot of heat in comparison to halogens. The output decreases as the bulbs age and I found replacing them every five thousand hours worked best. With the ballast ...


6

Peppers and some tomatoes will easily fruit indoors, provided they get enough light. You might want to try indoor avocados too, and keep the size small by pruning.


6

I have had several aloe plants derived from one tiny plant 29 years ago! I am in Michigan and they live on my window sill facing east so they get the morning sun. They have thrived so much that I have repotted several of the pups for centerpieces at a wedding shower and a baby shower. I did pot some to put on my outdoor deck one summer and the direct sun ...


6

Well, I'll make my comment an answer: Use rainwater for your plants (but please, do not drink unfiltered). In case you live in an apartment, you may consider this idea to harvest it.


6

if you want to grow chili peppers then you want lots of light. Getting a crop to grow indoors is far different than just getting a plant to grow. Your only feasible option is high intensity discharge lights. Wikipedia describes them as HID lamps have made indoor gardening practical, particularly for plants that require high levels of direct sunlight ...


6

The answer is the one I hate the most: it depends... Factors influencing your decision include: aesthetics: glass looks better than plastic if you are putting a greenhouse close to your house local climate: if it gets cold where you are then the material best suited for the snow load and that provides the most heat retention will be a better choice even if ...


6

I've built my own aero tank from an Ikea storage box and a 24V pond fogger. I started with these instructions and made a few tweaks and refinements over time, and the thing works quite well. Since there is no pump, and the fogger is perfectly quiet, all you can hear is a soft tinkling of water drops (the fogger knocks up a spray as well as fog). Add a grow ...


6

If you look on the spectrum further down, you will see it is nothing like "full spectrum" but two peaks that probably look to the human eye like decent white light. I would want more information before trying to use them for growing plants. Note also that this is a manufacturer selling them wholesale. After all that, this week's New Scientist (Jan 18-24, ...


6

You can do that, but not for more than a couple days, before giving them light again. You don't want to see any signs of etiolation, or you will have to 'harden off' the plants back into light. If you have to hold them longer than that, try to find some better lighting, indirect sunlight or a bright fluorescent or LED bulb. Even if it's cold, the darkness ...


Only top voted, non community-wiki answers of a minimum length are eligible