Plants

The Carbon Cycle (simplified)

Plants are multicellular organisms that gain energy through photosynthesis, though some species are parasitic or carnivorous. Unlike animals, fungi and other microbes, plants have cell walls made from cellulose.

Plants on Mars will be produced in greenhouses or grow rooms. In the longer term, plants might be adapted to the Martian environment as part of a terraforming program.

Significance to Martian Colonization

Plants are a vital source of food, carbohydrates and proteins, chemicals, and construction materials such as wood, straw and bamboo. Also, a well balanced carbon cycle delivers oxygen for breathing. Note that during exploratory missions oxygen will be brought along. In early habitats, oxygen will be made industrially, so plants will not be mission critical for life support. Only when the population gets large, will we try to make a biosphere.

Plant Selection

Greenhouse space and resources in a settlement are limited, and must be used carefully. Plants need to be selected carefully in order to provide the highest return on the resource investment.

Ease of Propagation

Selected plants must be easy to propagate through seeds, roots, or cuttings.

Hybrid vs Natural Strains

Hybrid plants, while common in terrestrial agriculture, are less desirable than pure strains. Hybrids are often sterile, and those that do reproduce sexually yield offspring that resemble the original strains more than the hybrid. Any hybrids grown in settlements will likely be propagated asexually through cuttings.

Genetic Diversity

Plants that reproduce sexually need enough genetically distinct individuals to prevent harmful inbreeding. Though disease and parasites will likely be left behind, there is always a risk of accidental exposure, or even the emergence of new diseases. A genetically diverse population has historically fared better than one with low diversity.

Ease of Farming

Greenhouses provide residents a great deal of control over the growing environment. Even so, certain plants must be excluded due to the difficulties involved in their growth. Many trees, for instance, grow too tall, and require extensive root systems that are impractical for small greenhouses.

Value

Plants should be selected based on the value they provide to the settlement. This could be in the form of food, natural fiber, chemicals, or even just raw biomass. Some plants, such as flax, provide multiple benefits.

Plants require light for growth. Various plants have different requirements, depending on their original environment on Earth.

Candidate plants for Martian greenhouses and production

Common Name	Scientific Name	Uses	Shadow tolerance	Production (tonnes/Ha/yr)	Notes	References
Aloe	Aloe Vera, Aloe Barbadensis	Medicine
Bamboo	Bambuseae	Construction, Fiber, and Food
Chamomile	Matricaria Recutita	Tea and Medicine
Flax	Linum Usitatissimum	Fiber, Oil, and Food
Hemp	Cannabis Sativa	Fiber and Oil
Luffa	Luffa Acutangula, Luffa Aegyptiaca	Food and Natural Sponge
Oats	Avena sativa	Food and Skin Care
Quinoa	Chenopodium Quinoa	Food
Soybean	Glycine Max	Food and Oil
Water hyacinth	Eichhornia Crassipes	Waste Water Treatment and Biomass
Wheat	Triticum	Food
Rice	Oryza Sativa, Oryza Glaberrima	Food and Edible Paper

List of Shadow Tolerant Vegetables

• Arugula (likes cool temperatures)
• Asparagus
• Beets (taste better in cool climates)
• Bok Choi
• Broccoli
• Brussel Sprouts
• Cabbage
• Carrots
• Cauliflower
• Celery (likes cooler climates)
• Chard
• Chinese Cabbage (will not tolerate hot temperatures)
• Collards
• Culinary herbs
• Fiddlehead of the Ostrich Fern
• Garlic (in low light conditions cloves are smaller, but just as flavourful)
• Horseradish
• Kale
• Kohlrabi (likes cooler climates)
• Leeks
• Lettuce
• Meslun
• Mizuna (likes cooler climates)
• Mustard Greens (low light makes it taste better)
• Parsnip
• Peas (especially snow or snap peas)
• Potatoes (prefer cooler weather, less sun will result in smaller tubers)
• Radish
• Rhubarb
• Rutabaga (also known as Canadian turnips)
• Scallions
• Spinach
• Swiss chard
• Stinging Nettles (harvest with care, but edible and highly nutritious).
• Tatsoi (likes cooler climates)
• Turnip (tastes best at cooler temperatures)

(Note, I'm no expert on plants, feel free to revise this list if something seems off to you, or if you know of an ideal plant for Mars.)