Adjusting Height on Grow Lamps Changes Light Delivery

October 29, 2018

Lamps that allow you to raise and lower them on the same fixture are handy for growing plants with different light requirements. Lowering the lamp reduces the light footprint but increases the density of light delivered. Raising it increases the light footprint but lowers the light density.

PC: SolTech Solutions

This is how you can use the same lamp to grow a full-sun plant and a shade-loving plant.

Gardening Under Lights Book


Rose Stem Cuttings

October 28, 2018

Roses are a great plant to propagate from stem cuttings. Make sure to remove some foliage from the stem before inserting into soil to reduce excess transpiration.

PC: Leslie F. Halleck

Since many new rose varieties are patented, it is important to only propagate for you personal use--never for sale or trading with neighbors.

Gardening Under Lights Book


How to Harvest & Save Wet Seeds

October 27, 2018

There are two main types of seeds: wet and dry. Wet seeds are produced from fleshy fruits such as tomatoes, eggplant, and squash. They typically remain inside a large amount of flesh and are not visible unless you break open the fruit.

Once tomatoes are large enough to develop mature seed, you can separate them from the fruit flesh.
PC: Leslie F. Halleck

When harvesting wet seed, rinse thoroughly to separate the seeds from the fleshy part of the fruit. After the seeds are completely clean, spread them out on a dry surface for several days before storing.

Gardening Under Lights Book


Grow Light Wattage per Square Foot

October 26, 2018

While you may use watts per square foot to give you a rudimentary idea of how much lighting you need, don’t rely on it as a measure of overall effectiveness. Remember, a lamp that uses a lot of power does not necessarily put out a lot of usable light, potentially leaving you with a hefty electric bill and wimpy plants.

Peppers growing in a 4-by-4-foot grow tent with a CMH lamp.
PC: Leslie F. Halleck

If you are growing tomatoes in an area of your home or in a grow tent, many sources will recommend about 40 watts per square foot to properly light tomatoes.

Gardening Under Lights Book


Grow Lights: What are Facultative Long-Day Plants?

October 25, 2018

Plants that do not require an exact photoperiod before they are triggered to flower, but will bloom faster or better with a specific photoperiod, are classified as quantitative, or facultative. Lettuce is a classic quantitative long-day plant.

Cosmos flowers and leafy lettuce growing side by side under the same lighting photoperiod.
PC: Leslie F. Halleck

While you might start your tiny lettuce seedlings under a long photoperiod of 16 hours, if you continue growing them indoors you must reduce that lighting period to 12 to 13 hours after you transplant the seedlings into their final container. If you continue growing them under 16 hours of light, the plants may bolt and go to flower too early, ending your harvest.

Gardening Under Lights Book


Collecting & Saving Seeds

October 24, 2018

Collecting and saving seeds from the plants you’re already growing is a sustainable approach to your gardening endeavors and a smart way to save money.

I use small sealable envelopes to collect and store my own dry seeds.
PC: Leslie F. Halleck

Dry seeds are easy to collect and store. Once you have harvested the seeds, leave them on a towel in a cool, dry place for a few days to ensure they are completely dry before you store them. Place them in a sealed container—such as an envelope, a paper seed packet, or a jar—and store in a cool, dry, dark place.

Gardening Under Lights Book


CFLs Are Good Grow Lights for Living Spaces

October 23, 2018

The light produced by CFLs is acceptable in your open living spaces. CFLs are a good lighting solution for smaller spaces, small grow tents, and areas where you do not want too much heat buildup.

This hanging lamp with a small CFL illuminates a potted gardenia.
PC: Leslie F. Halleck

Most CFLs are full spectrum, leaning to the cooler side, but you can also find them with a warmer Kelvin color-temperature rating.

Gardening Under Lights Book


Narrow Grow Light Spectrum With LEDs

October 22, 2018

Light-emitting diode (LED) grow-light technology allows you to narrow the spectrum of light you provide to just one color, referred to as nanometer specific light. You can purchase LED grow lamps that emit only a red spectrum of light or a blue spectrum of light (as well as other individual colors, such as orange and green).

This LED lamp emits only blue and red nanometer specific light.
PC: Sunlight Supply, Inc.

While you can use red and blue light exclusively and successfully, only a few species of plants are able to grow well under only red or blue light indefinitely.

Gardening Under Lights Book


Back to top

Tips in your inbox

E-Newsletter

Sign up for my monthly Halleck Horticultural newsletter for information about my horticulture courses and learning opportunities, plant and gardening information, and hort news. You can also sign up for my weekly Plant for Profits horticulture business newsletter.