Too bad about the small portion.
You can try to grow the HC emersed until the root structure appears again. Then afterwards separate into small parts, use tweezers and plant them apart. The more spaced out they are, the faster they will fill in the empty parts.
You can try to grow the HC emersed until the root structure appears again. Then afterwards separate into small parts, use tweezers and plant them apart. The more spaced out they are, the faster they will fill in the empty parts.