Most plants will put on more growth in more light, as a general rule. Plants need light, water, nutrients and warmth to grow; this is why plants put on the most growth in the summer. You can alter your light setup for indoor plants in several ways to encourage plant growth. Outdoors, try removing shade or even transplanting your plants to a sunnier location.
Make sure the existing light is as good as it can be. If indoors, clean the inside and outside of the windows near the plant. Windex or other window cleaner scrubbed off with old newspapers will give a clear window reliably. If there are screens, remove them and wipe dust off with a damp cloth or duster.
Reduce shade. If the plant at issue is outdoors, consider cutting back trees or shrubs that shade its light. Indoors, move the plant to a full-sun location, and observe it at various times of the day to be sure it is not shaded by nearby objects or furniture.
Hang more lighting. Find a full-spectrum high-wattage light bulb, the kind used in terrariums to mimic sunlight. If this is not possible, a high-wattage fluorescent bulb gives off the next best light. Install it in a hanging fixture above the plant, preferably one that directs light downward.
Invest in greenhouse lighting for more growth. High-intensity discharge lights are used to provide the most light to seed starts and early seedlings in greenhouses. Metal halide bulbs in particular produce blue spectrum light that encourages leaf growth. High-pressure sodium lights are the other high-intensity light, and give orange-red light that encourages flowering and budding. Choose whichever is best for your plant, and use both in combination with natural light.
Turn the lights off for a length of time each night. This supports the plant's natural day and night cycle and will help it conserve energy for growth at the right times. Artificial lights should be on for 10 to 12 hours each day and no more.