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The in vitro culture of unpollinated ovaries is one of the techniques used to induce gynogenesis. To explore the mechanism of lily gynogenesis and obtain haploids to shorten the breeding cycle, the in vitro effects of flower bud sampling time, exogenous plant growth regulators (PGRs), and different concentrations of picloram on embryo formation in unpollinated ovaries of Lilium L. 'Sorbonne' (oriental hybrids) were studied. The results indicated that flower buds ≥8 cm in length were most suitable. The PGRs picloram and 2,4‐dichlorophenoxyacetic acid (2,4‐D) with 6‐benzylaminopurine (6‐BA) or kinetin were useful in inducing ovule expansion in vitro. However, most ovules did not survive on the media containing 2,4‐D, whereas those grown on media containing picloram developed normally. In particular, a lower concentration of picloram (0.5 mg L−1) was found to be beneficial to the development of ovules into embryogenic shoots, whereas higher concentrations were more favorable to the development of shoots from the ovary wall. In total, 87 regenerated plants were obtained from unpollinated ovaries of Sorbonne. The chromosome ploidy of 20 of these was determined by counting root tip chromosomes, and eight of the regenerated plants were found to be haploids. Core Ideas: Longer flower bud is more appropriate for ovule development.Lower concentration of picloram promotes the development of ovule into shoots in vitro.Shoots obtained from ovules can produce more haploids.Through the ovule regeneration pathway, haploids can be obtained faster than by ovary culture.The ovary‐regenerated plantlets have different ploidy types from the mother plant. [ABSTRACT FROM AUTHOR]