Taproot
Definition: The taproot is the first root that emerges from a germinating cannabis seed, growing straight down and anchoring the plant. It develops from the embryo's radicle and later sprouts the lateral roots that form most of the root system. Growers usually plant sprouted seeds when the taproot reaches about 0.25 to 0.5 inch (6 to 13 mm) long.
How Taproot works
The white tail you see when a seed cracks is the taproot. Its tip senses gravity and bends downward, so even a root planted sideways will correct itself. The tip is also fragile. It has no protective bark, and the fine root hairs just behind it absorb most of the early water and nutrients.
Handling a sprouted seed
- Move seeds with clean tweezers held by the shell, never by the root.
- Make a hole about 0.5 inch (1.3 cm) deep, set the seed in with the root pointing down, and cover loosely.
- Do not let an exposed taproot dry out, even for a few minutes. Plant it straight away.
- If a root has grown longer than 1 inch, it is still usable. Plant a little deeper and handle with extra care.
Taproots after transplanting
Plants grown from seed directly in the ground keep a dominant taproot that can push 2 to 3 feet down, helping outdoor plants ride out dry spells. In containers, the taproot circles at the bottom and fibrous lateral roots take over. Fabric pots and air pots prune circling roots with air, encouraging more branching. Clones have no true taproot, one reason some outdoor growers prefer starting from seed after germination.