The ASTROCULTURE™ flight unit flown as part of the SPACEHAB-03 mission on STS-63 was a complete plant growth system providing plant lighting, temperature control, humidity control, water and nutrient delivery, a CO2 control system, nutrient control using the NASA Zeoponics system, an ethylene photocatalysis unit, a control and data acquisition system, and plant video. The objective of the ASTROCULTURE™-4 experiment was to continue technological assessment of these environmental control subsystems. Plants were included in this package for the first time. Two plant species were flown, rapid cycling ‘Wisconsin Fast Plants’ (Brassica rapa), and dwarf wheat (Triticum aestivum cv. ‘Super Dwarf’). Growth and development of both plant species on orbit appeared normal and similar to that of plants grown under terrestrial conditions.