Growing bulbs in water works best with paperwhites, which bloom in about 3 to 5 weeks with no chilling, and with pre-chilled hyacinths in a forcing glass. Keep the water just below the base of the bulb so only the roots drink, start in a cool spot, then move the bulb to bright light once shoots appear. Tulips, daffodils and crocus need 15 or more weeks of cold first.
Plants that grow in water include pothos, philodendron, lucky bamboo, spider plant, tradescantia, coleus and English ivy, plus kitchen favorites like green onions, sweet potato slips, avocado pits and pineapple tops. Most need only a clean jar, a node or root zone under water, bright indirect light, fresh water every week and a pinch of fertilizer for long-term growth.
Water culture orchids grow with their roots in or just above water instead of in a free-draining pot. The safer version is semi-water culture: a non-draining pot with chunky media and ¼–½ inch of water in the bottom. Full water culture (roots always submerged) has little expert backing, so test one plant first.
To grow pothos in water , cut a 3–6 inch stem tip with at least two nodes, remove the lower leaves, and stand it in a jar so the nodes are submerged. Keep it at 75–80°F in bright, indirect light. Roots usually form in 2–4 weeks. Refresh the water, and add weak fertilizer for long-term growth.
Here’s how to grow water spinach , but check the law first: Ipomoea aquatica is a federal noxious weed, and states like Florida and Texas require permits to grow it. Where it’s legal, root cuttings in water, plant them 6–10 inches apart in rich, constantly moist soil, feed every 4–5 weeks and harvest tender tips often.
To sprout an avocado seed in water , wash the pit, push in 3–4 toothpicks, and suspend it over a glass with the flat end down and the bottom always submerged. Keep it warm and out of direct sun. Roots usually appear in 2–3 weeks and a stem after about a month; pot it when the stem reaches 6–8 inches.
To root a pineapple top in water , twist off the crown, strip a few lower leaves to expose the stem, dry it for several days, then set just the stem base in water in a warm, bright spot. Once roots form, pot it in coarse mix. Extension guides plant the dried crown straight in soil, which also works.
Here’s how to grow sweet potatoes in water : push 3–4 toothpicks into a healthy root, rest it on a jar with the bottom half submerged, and keep it warm. Sprouts appear in about 2 weeks. Twist off 6-inch shoots, root them in fresh water for about 10 days, then plant these “slips” outdoors after frost.
You can grow potatoes hydroponically , but it’s one of the harder home projects. Tubers need a deep, dark, airy root zone, so a bucket or tote of perlite or coco fed by drip works far better than deep water culture or NFT. Start with certified seed potatoes, keep developing tubers away from light, and expect smaller harvests than leafy greens per square foot.
Hydroponics in space works differently than on Earth. NASA’s main station gardens, Veggie and the Advanced Plant Habitat, grow plants in clay-based media that wick water and nutrients to the roots, because loose water forms floating bubbles in microgravity. True water-based hydroponic and aeroponic methods have been tested on the International Space Station with the XROOTS experiment.