Some species of sundew (Drosera spp.), harvested from the wild for use in homeopathic cold remedies, are now endangered. This research consisted of two experiments in hydroponic production of sundew. The first investigated the effects of four nitrogen (N) fertilization levels (0.0, 5.1, 25.5 or 51.0 mg/L added N) and three harvest methods (after two months, four months, and sequential harvest at two and four months) on the growth of Drosera adelae (F. Muell.). In addition, the effect of N on the production of a medicinal active ingredient in D. adelae was examined. The second experiment investigated effects of the same nitrogen treatments in combination with three substrates (long fiber sphagnum, peat or rockwool) on growth. The growth rate of D. adelae was greatest at low levels of nitrogen fertilization, and slowed after two months of growth. Plants that were sequentially harvested had the lowest growth rate among all the harvest method treatments. Young plants and plants that received little or no N fertilizer had a greater water concentration than the other plants. Substrate and N level interacted, but generally peat and rockwool produced greater yields than did sphagnum. The medicinal compound plumbagin and a similar but unidentified compound were detected in the leaf extracts of D. adelae. However, whether N fertilization influenced the concentration of these compounds remains inconclusive.

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