How was the space version of the "grocery basket" created?

Those who are familiar with space vegetables know that what truly matters is never "where we get vegetables", but whether we can grow them in space. The answer is yes. Over a decade, the China Space Station has hung a vegetable basket 400 kilometers above the Earth.

Unlike the environment for growing vegetables on Earth, "growing vegetables" in space presents two main challenges: first, in a weightless environment, water has trouble penetrating deep into the root system. The microgravity environment in space causes a boundary layer to form around plant roots, preventing water and air from separating automatically. Plants must rely on external forces to carry out normal material exchange with their surroundings. Second, there is no sunlight inside the cabin, making it difficult for light-loving plants to grow.

To address the difficulty of water-air exchange in the root zone under microgravity, the space station's approach is to simultaneously reconstruct the root environment and the water supply path. The first solution: traditional soil is replaced by a regenerated cultivation substrate. This substrate is made by fermenting inedible parts of plants. It can support the roots, store and conduct water, and also preserve the necessary ventilation space for the roots. The second solution: water supply no longer relies on gravity-driven infiltration. Instead, it combines active liquid delivery with capillary water conduction to steadily deliver moisture to the root zone. At the current stage, China Space Station primarily still uses artificial cultivation substrates for growing fruits and vegetables. Water movement mainly relies on the capillary force of the substrate particles.

Without sunlight, plant photosynthesis must rely on a dedicated LED supplementary lighting system. By adjusting the ratio of different wavebands, light intensity, and illumination duration, a customized growth light environment is constructed for different varieties. Red light promotes stem and leaf elongation, blue light inhibits excessive growth to keep the plant shape compact, and white light supplements more complete spectral information. The illumination duration simulates seasonal photoperiods to control the timing of bolting and flowering. Every parameter is a customized "light recipe" for a specific variety.

Once the root environment and lighting system are set up, there are still two hidden hurdles. The first is fertilization. In a closed space with a limited amount of substrate, a slight excess of fertilizer can easily burn the roots. Tiangong uses controlled-release fertilizer: a resin coating seals in the nutrients, which are slowly released through micropores via osmotic pressure difference. Only one pre-application is required for the entire growing season, with supplementary fertilization unnecessary. The second is seed saving. The vegetable basket can't just produce one harvest. In 2022, the Shenzhou-14 crew completed a full life-cycle cultivation experiment of rice — "from seed to seed" — in the Wentian lab module. Cherry tomato seeds were saved for breeding, sweet potatoes were propagated through in-orbit cuttings, and leftover plants could serve as soil for new growth while the seeds they produced would become the seedlings for the next harvest.

When vegetables begin to grow stably 400 kilometers above the Earth, and when seeds are passed down from generation to generation without relying on ground resupply, what we have planted is no longer just a vegetable garden, but a new frontier for future agriculture.

Reviewing Expert: Li Baoju, Researcher, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences

Sources:

[1] China National Space Administration: How is "Tiangong" Vegetable Growing Achieved?

https://www.cnsa.gov.cn/n6758968/n6758973/c10442680/content.html

[2] China Manned Space: Expert Class | The Growth Record of the "Tiangong Vegetable Garden"

https://www.cmse.gov.cn/xwzx/202604/t20260417_57406.html

[3] China Manned Space: Arbor Day | Checking in on the "Space Vegetable Garden" Worth Looking Forward To

https://www.cmse.gov.cn/xwzx/202503/t20250312_56376.html

[4] CNR News: Lettuce, Rice, Tomatoes, Scallions... Over 10 Years, the "Tiangong Vegetable Garden" Has Grown Rich Varieties with Continuous Harvests

https://news.cnr.cn/native/gd/20260418/t20260418_527590345.shtml