Juvenile growth rates play an important role in demography, as they shorten time to maturity and often dictate how long individuals remain vulnerable to predation. However, developing a mechanistic understanding of the factors determining growth rates can be difficult for wild populations. The gopher tortoise (Gopherus polyphemus) is an ecosystem engineer threatened by loss and deficient management of its pineland habitats in the southeastern United States. To aid management, we investigated the factors governing growth of immature gopher tortoises and explored use of drone-based imagery as a habitat assessment tool. From 2021-2022, we captured, measured, and radio-tagged immature tortoises in native sandhill and human-modified, ruderal habitat in south-central Florida. We used quarterly, high-resolution drone imagery to quantify plant cover types and vegetation indices at each occupied burrow, and measured frequency of occurrence of forage species by hand. Annual growth rates of immature tortoises in ruderal, grass-dominated habitat were higher than those in shrub-dominated sandhill and were the highest published for this species (x̄ = 34.4 mm carapace length/year). Models based on drone-derived data were able to explain similar proportions of variation in growth as those based on ground-based measures of forage, especially for data acquired during the late dry season when both types of models were most predictive. Habitat differences in forage nitrogen content were also more pronounced during the late dry season. Despite concerns about potential growth-survival trade-offs, tortoises in ruderal habitat did not exhibit lower apparent survivorship. These findings indicate that habitat dominated by nutritious non-native grass can provide a valuable supplement to native sandhill through the mechanism of increased growth rates due to higher forage quality, especially in late dry season. Finally, our study demonstrates that drone technology may facilitate management by providing less labor-intensive ways to assess habitat quality for this and other imperiled herbivores.