Leachate nutrients from the nursery of containerized tree seedlings result in risks of inefficient fertilization through nutrient loss and contamination of ground water. In the present study, seedlings of Buddhist pine (Podocarpus macrophyllus) and Japanese maple (Acer palmatum) were cultured in containers of three differing sizes under contrasting photoperiods of naturally 11 h per day and an extended one of 20 h per day. Controlled release fertilizer (CRF, 14-14-14) was used to feed seedlings with sufficient nutrients for 5 months from June to November 2014. At the end of experiment, seedlings from all types of containers were measured for height and root collar diameter, whilst leachates were collected to determine nutrient concentrations of available phosphorus (P), potassium (K), ammonium and nitrate nitrogen (N) therein. Growth of both seedling species increased with the volume of container, but only growth of Japanese maple seedlings responded to photoperiod. In spite, there was greater amount of nutrients leached from containers planted with Buddhist pine than with Japanese maple; nearly no nutrient in the leachate affected by photoperiod. A negative correlation was found between concentrations of leachate nutrients and seedling height growth in all container sizes. In conclusion, nutrient leaching is a nonignorable but predictable factor by seedling height growth during the intensive culture of slowly growing seedlings of ornamental trees under the extended photoperiod.