Basil is a valued plant species due to the specific taste. The crop is based on seedlings and it is used as a spice in fresh, frozen or dried state. In the production of seedlings, there is an endeavor to replace the organic peat base substrates by other suitable materials. The aim of the study is to determine the possibility of replacing part of the commercial organic substrate with sheep wool in the cultivation of seedlings, while observing the effect of substitution on the morphological characteristics and the proportion of dry matter in seedlings. The experiment was set up with different weight ratios of unprocessed sheep wool (1%, 5%, 10%, 15%, 20%), controlled without wool supplement (0%), using methods of randomized block design in four repetitions. Seedlings were analyzed 35 and 70 days after sowing seeds. It was found that treatments with 15% of sheep's share of wool in the first measurement and 20% in the second measurement gave best results in all measured morphological parameters (plant height, number of nodes and leaves/plants, dimensions of the largest leaf/plant, fresh weight of seedlings). In the treatment without added wool, the seedlings were the least developed and the part of the dry matter was the same in all treatments. The conclusion is that organic substrate can improve growing of basil seedlings by adding the 20% share of unprocessed sheep wool.