1000 w is very powerful and it get hot! 2-4 inches will cook the plants even through the soil. place 1000 w exactly 1 meter (that should be more than 3ft) from the tip of the plant. keep the lights one more than 20hrs a day. when they grew 18inch to 24inch then change the cycle to 12 hours of light a day. lower the humidity and change the nutrients to high P (ex. 10-60-10, N-P-K). after this, they should grow fine.