315W LEC/CMH Cannabis Grow Setup & Tutorial

by Nebula Haze

See Other Examples of Cannabis Growing Setups

315W LEC Grow Setup (For Hobbyist Growers)

• Average Yields: 7-13 ounces (we’ve harvested as much as 17 ounces, learn how)
• Recommended 2-8 plants
• Grow space: at least 2×4’ or 3’x3′ with a height of 5′ or more
• Estimated Cost: $745+ ($825+ with professional smell filtering)

Learn how to get the best yields in this 315 LEC setup.

About This Setup

The 315W LEC grow light (a brand name version of the “Ceramic Metal Halide”) is relatively new to the growing scene and is a popular alternative to HID lighting. It excels in the vegetative stage where it produces fast growth, though it also does a great job in flowering by producing strong, sparkly bud. LECs provide a significant amount of UV-A which may explain why the buds tend to look so glittery.

Pros: One bulb for the entire grow, great results, non-suspicious colored lighting, great for SOG

Cons: Needs significant height above plants, the LEC itself is pricey by comparison to HIDs

Learn more about growing cannabis with LECs

315 LEC Grow Light for Growing Cannabis

• Average Yields: 7-13 oz ounces (follow these 8 simple steps to harvest up to 1 pound)
• Plants: Recommended 2-6 plants
• Optimal grow space is a 2’x4’x6′ grow tent
• Actual Power Consumption: About 330W at full power
• How Far to Keep from Plants: 24″ from the top of plants in the vegetative stage, and 18-24″ away in the flowering stage. If top leaves look stressed move the light further away.
• Pros
  • Great yields
  • High “sparkle” on buds
  • High smells/terpene production in lab tests
• Cons
  • Gets super hot for the size (best for a cold grow room)

Estimated Cost: $745+ ($825 with professional smell filtering) plus the cost of seeds

View a full growing tutorial using LEC grow lights

Complete Grow Supply List

This cannabis grow room setup list includes all the supplies you need to get to harvest.

Grow Light

315 LEC Grow Light

• The model I recommend is this 315 LEC/CMH Grow Light from iPower.
• Cost: ~$170 (the price fluctuates on Amazon so if it’s higher try shopping around)

This iPower LEC grow light is an excellent price because it is a “generic” fixture (listed as a ceramic metal halide grow light, which is the same as an LEC, but not a “brand name” one) yet gets the same results as the “premium” Sun System LEC model

iPower 315W LEC/CMH Grow Light

Grow Space

• Grow Tent Recommended Sizes
  • 2’x4’x6′ (smallest size) – an example is Cool Grows 48”x24”x72” grow tent.
  • 3’x3’x6′ (the size the 315 CMH/LEC light is designed for) – CoolGrows 36″x36″x72″
  • 4’x4’x7′ (jumbo size – never worry about space, can upgrade to a bigger light later) – an example is CoolGrows 48”x48”x80”
  • Learn more about grow tents
  • Cost: ~$80-100
• Exhaust Fan
  • A quality 6″ inline exhaust fan works best. Avoid small cheap “booster” fans as they usually don’t have enough power to exhaust all the hot air effectively. Hang from inside tent to help keep quiet.
  • Example 1: Cheap but loud VIVOSUN 6 Inch 390 CFM exhaust fan.
  • Example 2: Quiet but expensive AC Infinity CLOUDLINE S6 or CLOUDLINE T6 (T6 version is the same fan but has a digital interface)
  • Cost: $120 for Cloudline S6
• (Optional) Carbon Scrubber
  • Use with an exhaust fan to effectively remove smells Learn more about controlling odors.
  • Note: it’s typically cheaper to get a kit that contains both the exhaust fan and filter than buy them separately.
  • Recommended: 6-inch Carbon Filter, 6″ x 16″ version
  • Cost: ~$80

Learn more about choosing and setting up an exhaust fan and carbon smell filtering.

Plant Pots

I prefer fabric pots or air pots because cannabis plants grow faster. However, standard hard-sided plant pots also work well and can be watered less often.

• Recommended: Fabric pots between 2-7 gallons (here’s the brand I used last but I just pick what looks good because any fabric pots work great)
• Alternative: Regular plant pots between 2-5 gallons

Cost: $20

Plants grow faster in fabric pots compared to hard-sided pots, but need to be watered more often

Grow Medium (Soil, Coco, Hydro)

Grow mediums can include coco coir or soil (hydroponics for more advanced growers) but if you’re not sure, a coco-based soil like Coco Loco is perfect for beginnners.

• Recommended Soil: One 2 cu ft bag bag of coco-based soil with perlite should be able to fill 15 gallons worth of pots. For example, it will fill 5 x 3-gallon fabric pots.

Cost: ~$40

Coco Loco is a coco-based soil that makes thriving cannabis plants

Nutrients

• You need a “vegetative” or all-purpose plant nutrient for the first part of your plant’s life
• You need a “bloom” or low-nitrogen nutrient for the budding phase
• Many nutrient systems have a nutrient schedule so you give your plants the right ratios for each stage of life
• Always start at half strength with a new base nutrient system because the recommended strength is typically too high for cannabis

Get examples of great cannabis nutrients

Recommended Nutrients: Dyna-Gro Grow + Bloom nutrient combo is excellent, cheap, and easy to use for growing cannabis.

• “Grow” bottle: Give 1 tsp per gallon of water during the vegetative stage
• “Bloom” bottle: Give 1 tsp/gallon of water during the flowering stage

Learn about other cannabis nutrients we recommend

Cost: $25

Dyna-Gro Grow + Bloom is my recommended nutrient system for newbies. One bottle for veg, one for bloom. 1 tsp/gallon. Super simple!

Other Supplementary Items

• Get your seeds – $5-12/seed (on average, can be more or less depending on the breeder)
• 24-Hour Timer (to put your grow lights on a timer so the plants get a day and night period on a schedule). Why do cannabis plants need to be on a day/night schedule? What about autoflowering light schedules? – $10
• Water containers (I personally use a 3-gallon or 5-gallon water jug to mix up nutrients, but anything can work) – Much cheaper at Wal-Mart ($5-15) than online!
• Extra 1/8″ Rope Ratchets (sooooo handy) – These can be used to hang your grow light or carbon filter from inside the tent, and still be able to easily move it up and down without needing any strength. Your grow light usually comes with a set of rope ratchets, but it’s a great idea to get an extra set to hang the carbon filter – $15
• Thermometer/Humidity Monitor with a probe so you can keep track of the temperature inside the tent – $15
• PH Test Kit – Prevent potential nutrient deficiencies by testing the water pH: https://www.growweedeasy.com/ph – $15
• Measuring spoons for measuring out your nutrients (many people already have these) – $10

Learn about other cool growing tools

Estimated Cost: $745+ ($825 with professional smell filtering) plus the cost of seeds

See Additional Grow Setups

Cannabis plants growing under a 315 LEC Grow Light

CMH grow lights produce extremely fast and healthy vegetative growth. These plants are only 29 days old.

Cannabis plants flowering under a 315 LEC Grow Light

A 315 LEC (CMH) Grow Light Fixture by Sun System

Example of buds grown under a 315 LEC grow light from seed to harvest in this setup (pictured above and below)