Kjellmaniella crassifalia Miyabe is one of the valuable seaweed crops cultured in the Korean coastal waters of the East Sea. Unfortunately recent environmental changes have adversely influenced its growth, prompting the need to develop techniques for species restoration. To obtatin biological information, the growth of the species was monitored for one year. The maximum blade length, $110{pm}45cm$, was attained in July, and zoospores were released in November. The optimum culture conditions allowing juvenile sporophytes to grow to young blades consisted of $20{mu}mol/m^2s;at;10^{circ}C$ under which the blade length grew to $1,732.5{pm}143.3{mu}m$ in 42 days. Sporangial sori started to form in September, reaching 85% maturity in November and 89% maturity in December. Examining the growth of the species according to depth, the individuals growing at 5 meters grew the most, reaching a blade length of $75.9{pm}18.9cm$ in August.