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Indoor Gardening

When we do our plant sales or shows in suburban DC, we started noticing that many people that stopped by our booth would claim that they didn't have any space to grow any plants. They were either living in a condo or apartment with or without a small balcony or patio.

I was intrigued by the idea of bringing permaculture into our homes and started thinking about what the barriers were to being able to grow some food in these limited spaces. I wanted to share the progress on some of my investigations and show that even if you can only garden indoors, you can still grow enough of your own food to impact your health and budget.

Why do we need to have plants in our indoor spaces?

The average American home today is 1800 square feet, larger than at any point in the country's history. We also spend almost 87% of our time indoors. So how is all of this indoor time affecting our health?

VOCs revealed

In the early 1970s, when NASA was starting to design SkyLab, their first space station, they discovered that the materials used in the construction of the space station actually produced gases that contained harmful organic chemicals. What was worse was that the concentration of these organic compounds inside enclosed areas was many times higher than what one would find in a natural outdoor environment. They labeled these out-gassed chemicals VOCs, or volatile organic compounds.

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Following up on this study, one of the environmental scientists, B.C. “Bill” Wolverton, discovered that some plants actually absorb these gases and reduce the concentration of VOCs in the indoor environment. He went on to publish a list of easily grown indoor plants that were most effective in absorbing VOCs.

Essentials

So if growing plants indoors can be good for our health, which plants do we choose that thrive in indoor environments? And how do we take care of them properly? Let's first deal with essentials that every plant needs so we can formulate effective strategies for dealing with these hurdles.

Sun

This is the main issue with growing indoors; many homes don't allow adequate natural light in, and artificial light quite often doesn't provide the correct frequencies of light that plants are tuned to absorb. For most North American addresses, it's preferable to have south or west-facing windows for growing since they will gather the most sunlight as the sun tracks across the sky. There are some handy phone apps (Sun Surveyor and SunCalc) that you can use to determine how many hours of sunlight you get for specific windows. 

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If you don't have a good window situation, there are a number of ways to introduce more light into your home. The most convenient and simplest method is to install a grow light. Growlights usually come as either fluorescent or LED arrays, providing enough energy to easily start seedlings and grow leafy crops like lettuce, parsley, and basil. Fluorescent bulbs tend to use more energy than LED lights and don't provide as wide a range of light frequencies, but they are much cheaper. Although LED lights cost more initially to purchase (around $40 for a LED bulb, plus $40 for an enclosure), they will produce healthier seedlings and plants in the long run and save energy costs.

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Although expensive to retrofit into houses, solar tubes are an effective way to literally pipe sunlight from your roof into interior rooms. Some of these systems use fiber optics cables to transport the sunlight over 50 feet into interior rooms. A crowdfunded project called Caia uses a sun-tracking parabolic mirror to reflect light from outside into ambient light for outside-facing rooms.

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Water

The indoor of modern houses mostly use forced air pumped through vents to heat and cool the environment. Unfortunately, this increases evaporation and desert-like conditions for our plants indoors. Because pots and soils are constantly drying out, the need for constant watering gets burdensome and can lead to instant plant death on those days that we forget to water or if we go out of town.

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Mulching with coffee grounds or coco noir can help to delay the rate of evaporation, but inevitably we need a solution for automatic watering. The easiest solution to provide automatic watering is to purchase or construct a self-watering planter. In a self-watering design, a reservoir of water is located underneath the actual pot, separate of the soil, and uses wicking capillary action to suck up water into the pot. Because this action is passive it doesn't suck up too much moisture and is self-regulating. I've been working on an instructable for building your own sustainable planter in GIY, but here are some other places you can get a planter.

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Another, slightly more tech-heavy solution involves using an automated timer with a pump; of course if you are home-schooling you can view this as an opportunity for a project. This involves having a container you can use as a water reservoir. You hook the automated timer up with the pump and it will periodically squirt water from the reservoir into your pot when the timer is set. 

The only problem with this setup is making sure little details are correct, like making sure the tubes are secure, purchasing a timer that can be activated for period of time less than a minute, and finding a small or adjustable pump.

Soil

Going hand in hand with water availability for your plants is making sure they are in the right kind of soil. Many gardening experts will advocate creating non-soil blends using perlite, vermiculite, coconut coir, peat moss, or, if they are progressive, biochar. Most of these recipes are recommended on the basis that regular soils become either dried out or too moist indoors.
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Unfortunately, most of these alternatives to soil are not sustainable, and quite often cost a lot more than their benefit to your indoor plants. Permaculture design works with nature to promote healthy gardening and this works well in outdoor situations; soils teeming with life and supporting a diverse and healthy ecology. The problem indoors is that we don't really want to support the same kind of ecology. An overabundance of fungi in your indoors soils might lead to an excess of spores causing allergies and breathing problems. Supporting large numbers of insects in your indoor pots usually leads to them exploring elsewhere in your house for more resources.

So how do we solve this soil dilemna? I'm still researching the ideal balance of ecology vs utility, and probably have a higher tolerance for insects than most of our readers, but I can share a few tips I've picked up.

Larger pots are almost always better than small pots because the amount of soil supports a healthier ecosystem. Ideal pots would be long skinny self-watering planters.

One of the few animals that I've found really behaves itself indoors are worms; whenever you first fill your pot with soil, add a small amount of kitchen waste in the bottom with a healthy handful or two of earth worms. They'll survive pretty easily and help to regulate both the moisture and bacterial population in your soils.

I've found that using aged compost is perfectly fine for indoor soil uses, and is much cheaper than buying alternative options.

Indoor Plant Choices

In the beginning of this article, I talked a bit about VOC-absorbing plants. However, don't feel limited to just growing these plants in your indoor spaces. There are plenty of choices that will actually do better indoors in a strictly regulated environment than outdoors in some chaotic temperate zones. I've listed briefly some suggestions for cultivating an abundant harvest indoors.

Tropical

Many tropical plants are easy to take care of in containers and are self-fertile so they can produce fruit or berries indoors. It's usually a good idea to put them outside on a patio or deck in the summer to boost your harvest, but many of them can survive the whole year inside your house. Some possibilities include:
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Dwarf Banana

These varieties grow fast, up to a maximum of 6-7 feet. They have nice foliage that can be used to wrap and flavor foods and can even produce 1 or 2 bunches of bananas a year if they get good sun.

Citrus

Dwarf lemons, kumquats, and limes are easy to grow indoors and can produce fruit year round. Keeping soils moist but not wet will make sure their roots don't rot, but aside from that, these plants are perfectly happy in containers.

Fig

Fig trees are easy to grow inside because they prefer slightly drier soils. Try varieties that are suited for container culture like petite negri; they'll be easier to prune and won't become as root bound as other varieties.

Mushrooms

Growing mushrooms indoors is actually an ideal choice because most mushroom varieties prefer little to no direct sun. Some varieties are very easy to cultivate indoors; instead of growing in pots, they grow on substrate, which is a fancy word to describe a block of material the mushroom grows on. Different mushrooms prefer different substrates, and as they colonize and eat through the food in the substrate, they eventually produce pin-sized heads that swell into large edible bodies.

An easy place to start is by purchasing an indoor mushroom kit (available from Mushroom Mountain and Field And Forest), which already comes with the substrate innoculated with the mushroom of choice. Only a few weeks after receiving your kit in the mail, you can harvest 2-4 pounds of shiitake, oyster, or crimini/portabella mushrooms. After your kit is "spent", you can put it in your compost or garden bed and easily add to the fertility of your garden.

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Sprouts

A 1020 seed tray can produce about 1/2 lb of sprouts in a week, more than enough to sprinkle in sandwiches and stews, or just to snack on raw. When you are done with your tray, you can dump the roots into your compost or garden, and immediately start again with a thin layer of soil. Rotating in sprout trays each week can easily produce 20 to 25 lbs of sprouts a year.

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In the past decade or so, the benefit of sprouted foods has begun to be appreciated and researched. As a "super" food, it's easy for us to start our own sprouts indoors instead of paying exorbitant rates from a supermarket. Sprouts are simply seedlings that are in their first week of germination. Although you can save some money by ordering these seeds in bulk, it's actually more convenient and not terribly expensive to use blends. Consuming regular amounts of sprouts will boost your vitamin and mineral intake naturally and cost much less than buying processed vitamin supplements that aren't as effective.

Herbs

Many culinary herbs (rosemary, marjoram, basil, oregano, lavender, thyme) have Mediterranean origins, where the climate is naturally drier. This makes growing many culinary herbs indoors a snap; you can sprinkle these seeds on the surface of an herb pot to get started. Just make sure to keep basil, parsley, or coriander separate from your other herbs since they grow much faster (being annuals).

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