Help my plants pretend they're outside

January 1, 2009 3:10 PM

How do I best grow plants under artificial sunlight? What will I need?

I live in a "garden-level" apartment, which is ironic because most gardens require sunlight to thrive. My apartment has almost none. Plants would go a long way in making this apartment much less dreary/stuffy, but I'm not really sure where to start. I think my biggest hangup is lighting - what kind of lighting do I need? I do have limited funds - I'd like to spend < $200 on everything - pots, soil, lights, seeds, etc.

I'd like to grow some common houseplants, and maybe a smattering of fresh herb/spices for cooking. My google-fu is resulting in confusing/conflicting information or info on growing a certain cash crop, which I'm not interested in. I know about the aerogarden for herbs, but that whole setup seems a little pricey for what it is.

Any recommendations on lighting, soil, plant food, plant types, or other hints would be greatly appreciated. I have little to no experience gardening, so please type slowly. Bonus hotness for links to any trusted online retailers. I'll answer any questions below. Thanks!

posted by antonymous to home & garden (4 comments total)

Growing houseplants and herbs with artificial lighting is not an easy thing to do. The sun is a *lot* brighter than people think it is. You are not going to be able to replicate that, especially with a budget of $200.

If you want houseplants, find plants that require very little light. If you want herbs, you will be recreating the Aerogarden setup, or something close to it.

The Aerogarden is well worth the cost, especially if you cook.
posted by bh at 3:53 PM on January 1

Info on growing a certain cash crop is generally applicable to most herbal crops, except for the part about inducing vegetation or flowering by manipulating day/night periods which doesn't apply to all (or even most) herbs.

Fluorescent lighting is almost certainly your best option for an indoor kitchen garden. High-intensity discharge lamps give you more light per cent spent on electricity, but they're unpleasant things to live with because they are intensely bright point sources that run hot, and the ballasts tend to buzz a fair bit. So, go for fluorescent grow tubes. Use at least four four-foot tubes in mirrored reflective fittings without diffusers, positioned about six to twelve inches above the plant tops, surround the growing area with reflective surfaces (matte white paint is very close to best) and use a light-colored mulch over your soil (shredded office paper works well) to maximize the amount of light available to your plants.

When you're budgeting for this exercise, don't forget the cost of electricity. If you have an indoor kitchen garden with, say, 160 watts of fluorescent lighting (four four-foot tubes) running say 15 hours per day, and electricity costs you 20 cents per kilowatt hour, you will be spending 20 cents/kWh * 0.16 kW * 15 hours/day = 48 cents/day on electricity.

Grow lamps have a weird light spectrum that some people find unpleasant: lots of reds and blues and almost no green. Plants can't use green light much (they look green because of all that green light they're reflecting), so there's not much point spending electricity to generate it. You'd need at least six standard-spectrum tubes to give you the same growth rates you can expect from four grow tubes.

Good potting soil with occasional application of properly diluted liquid fertilizer will give you at least 90% of the growth rates you can obtain with hydroponics, provided the pots are not disproportionately small compared to the plants you're growing in them. For a herbal kitchen garden, six inch pots should be fine. Aim to keep the soil about as damp, on average, as a well-squeezed sponge. Overwatering will kill plants by drowning and rotting their roots.

Your herbs will do better with a breeze than without, so put a little bank of low-noise PC fans in the back of the garden. You can run more of these than you will ever need off a discarded PC power supply. Forced air + growing herbs = yummy smelling kitchen.

As for general houseplants: the general rule is to grow them as close to your windows as you can arrange. If your interior is generally dim, you need to pick plants such as ferns that are naturally adapted to growing in dark forest understory.
posted by flabdablet at 5:20 PM on January 1 [1 favorite has favorites]

(I do a lot of outdoor gardening and worked in horticulture in the past - orchids - and I've been investigating this lately as my wife and I have been talking about the possibilities of growing cooking herbs indoors on the relative cheap.)

Your options are to work with lower-output conventional fluorescents, which are cheaper but more work to grow effectively under. I've started seedlings for the outdoor garden under ordinary fluorescent tube fixtures and they produce sufficient light for growth but you have to keep them very close over the plants which means adjusting the height between lights and plants a lot. Seedlings are easy enough but getting good growth under regular fluorescents is tough.

Higher output lamps are easier to work with and produce better results but they are costly. The Aerogarden uses a full-spectrum compact fluorescent lamp something like this. I've never worked with these particular bulbs but I use a Hydrofarm lamp to do seedling starts and occasional special care for my light-loving houseplants and it is a solid product. I've heard reliable endorsements of the newer High Output T5 Fluorescent fixtures, but they are fairly expensive. High intensity discharge (HID) lamps like metal halide and high pressure sodium produce the most intense light and you could grow most anything with them, but they are quite costly, $200 is the lower end for the smallest fixtures.

You will need a place grow (some sort of table or stand - water and dirt will get spilled so you need to be mindful of keeping the growing area contained and keeping water away from electricity) and a way to hang the light and raise and lower either the light or the plants. Reinforcing your light (having a reflector over the bulb and the growing area having walls or panels that reflect light back - a matte white surface is best, you don't need fancy mylar or anything) makes a significant difference with indoor lights. Hydroponics is a lot trickier than growing in dirt: don't bother with it, it is a technique geared towards large scale and automation.

I agree with bh that for houseplants, focus on low-light, hardy varieties rather than trying to spot-light several plants or having to restrict all your houseplants to a growing area. And this is something you can get started with without any special preparation.

You may find less marijuana centered information searching for the term "container gardening" rather than "indoor gardening." This is a nice general-purpose book that I think is out of print but not so hard to find used or in libraries. The library in general is a good place to look, there is plenty of information out there about growing in containers that is geared towards conventional, legal plants.

Finally, I'd suggest rather than mail-order you find an actual store. Brew and Grow is a very decent Minneapolis-metro based store I have patronized in the past, I know there are others. While people are obviously using this equipment for growing marijuana, plenty of people use them for conventional gardening (especially the more hobby-scale equipment) as well so there's no need to be cagey about shopping at this sort of place. You can talk to someone about what sorts of plants you want to grow, the amount of space you have, and so forth. Lighting fixtures can be very large and you should look at what you're dealing with in person before you buy something.
posted by nanojath at 6:22 PM on January 1

I've had good luck with a few inexpensive CFL grow bulbs from a local indoor gardening place. The boxes say "energy used: 40 watts, light output: 2650 lumens" (as opposed to 60-watt CFL replacement household bulbs, which say 14 watts used/854 lumens.) They work in standard sockets and and I hung them over the plants with open-bottom Ikea shades. Bonus: They don't look half bad that way, and the dim Pacific Northwest winter seems noticeably cheerier!

Each of these contraptions cost about $30 to put together. At first the plants didn't do much, but after I put the lights on vacation timers to mimic summer (15-16 hours), they've perked right up. I've got streptocarpus, abutilons, and even two hibiscus plants blooming away right now. The fuchsia is less enthusiastic but still blooms occasionally. All the foliage plants are all growing like crazy.

Hope this helps!
posted by bunji at 9:21 PM on January 1