Grafting is widely used in the commercial production of cucurbits (Cucurbitaceae) and solanaceous (Solanaceae) vegetables, but seldom in the production of cruciferous vegetables such as cabbage (Brassica oleracea Capitata group). In our study, we developed a tube grafting method for cabbage using the ‘K-Y cross’ cabbage as the scion and ‘Tsuei Jin’ chinese kale (B. oleracea Alboglabra group) as the rootstock (K-Y/TJ), and then used the K-Y/TJ grafted seedlings to identify the best healing conditions. The examined healing conditions included temperature (15, 20, or 25 °C), relative humidity (RH; 75%, 85%, or 95%), and light intensity (high light intensity, 79 to 107 μmol·m–2·s–1; low light intensity, 38.6 to 58.8 μmol·m–2·s–1; or full darkness, 0 μmol·m–2·s–1). Considering all the healing conditions, the K-Y/TJ grafted seedlings healing at 20 °C, 95% RH, and high light intensity exhibited survival rates of up to 96.7% and overall superior seedling quality. ‘K-Y cross’ cabbages were then grafted onto chinese kale rootstocks, and the head traits of all grafted plants were comparable to those of nongrafted and/or self-grafted ‘K-Y cross’ plants. ‘K-Y cross’ plants grafted on ‘Jie Lan’ chinese kale rootstocks had greater ascorbic acid and total soluble solid (TSS) contents than nongrafted and self-grafted ‘K-Y cross’ plants. Overall, this research describes a successful tube grafting method and the optimal healing conditions for grafted cabbage seedlings, which can be used as a tool to improve head quality.