One of the fundamental concepts used by Earthships is to recycle all water from the sinks and showers (“gray water’) and purify it using an indoor planter prior to use as toilet water.
Plants play a vital role in maintenance of an Earthship. To further sustainability and independent living, food producing plants are grown.
Each Earthship owner decides what plants could be grown. Once decided, it is recommended to plant multiple plants, placing them in different conditions. This will help to show where the plant will be most successful. Even plants within the same five foot vicinity can yield different results. It all depends on the amount of sunlight to shade rations, the quality of soil, and other factors.
A good example of this was observed at the Phoenix Earthship. Two spikes, or dracaena plants, were planted simultaneously. The only difference between the locations was one plant received two and a half hours more sunlight than the other plant. Within two years, one plant has exceeded five feet, while the other plant hasn’t even reached three feet.
For the most part, perennials are unable to work inside an Earthship because they need to die off during winter, and Earthships maintain a constant 70* temperature year-round. However, a few tender perennials, such as the Butterfly Bush, can survive in an Earthship. One of the popular plant options for an Earthship is the banana tree. These trees can handle most lighting conditions, while reaching heights of 12 to 15 feet. Plus fruit can be produced early on.
For the best results, a neutral or slightly acidic soil is recommended for use in Earthship planters. Most plants, whether food, herbs, or other plants prefer a soil pH level between 7.4 and 6.0. Most nursery and other garden supply stores offer pH testing kits that are cheap and easy to use. You can also get any other supplies needed to improve your plants health.
There is only one situation in which sterilized soil should be used, and that is when you are germinating seeds and have harmful soil born disease and or insects. This can include mildew, cutworms, or various others. Young plants cannot survive these disease or insect infested soil.
Healthy plants need healthy soil. When healthy, a plant will attract fewer insects and are less likely to get a disease. Although most bugs will not kill your plant, insects can weaken your plants. A weakened plant is more likely to get a deadly disease or mold. It is important to remember to not all insects are harmful. There are a large number of insects that help with pest control. Commercial insectaries, garden supply stores, or nurseries can help you order a variety of beneficial insects or mites.
You can avoid introducing other insects for pest control with a number of methods. This includes: removing infected leaves from both your plants and your home; removing flying insects (vacuuming); or using a water spray.
Fortunately, weeds are typically not an issue with indoor greenhouses. Screen doors prevent the weed seeds from gaining access to the plants and prevent beneficial insects from leaving the greenhouse. The only organic weed removal method is to pull weeds by hand.
Because greenhouses in Earthships usually use gray water, and hence there may be soaps in the water, it is highly recommended that one always use biodegradable products. Any harsher cleaning products, such as bleach, should never be presented to your plants.
As of October 2009 the following plants have been grown in an Earthship:
Fruits and Vegetables: Artichoke, Arugula, Bananas, Black Seeded Simpson, Blood Orange, Broccoli, Broccoli, Cabbage, Cantaloupe, Carrots, Chard, Coconut, Corn, Cucumber, Figs, Frisee lettuce, Grapefruit, Grapes, Green Onions, Kale, Lemon, Lettuce, Lime, Lolla Rossa, Mizuna, Peas, Peppers, Pineapple, Purslane, Royal Oakleaf, Spinach, Squash, Strawberries, Tangerine, Mango, Tomatoes, Watercress (which is grown via the pond), Watermelon, and Zucchini.
Herbs: Basil, Chives, Cilantro/Corriander, Dill, Marjoram, Mint, Oregano, Parsley, Sage, Rosemary, and Thyme.
Edible Flowers: French, Fuchia, Geranium, Hibiscus, Honey Suckle, Nasturtium, Passion Flower, Rose, Snapdragon, Sunflower, Viola, and Yucca.