Every crop has its own optimal humidity level, which may change depending on the stage of growth. On average, a good target for plant growth is about 50 percent humidity. Plants growing in low humidity will dry out faster. When the air around a plant is dry, it creates a high vapor pressure deficit (VPD).

Plants that dry out because of low humidity in the air become more susceptible to disease. Pests like spider mites love dry conditions and will attack plants that are already stressed from a lack of moisture.

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African violets are a classic indoor houseplant. But there's nothing old fashioned about them, as far as I'm concerned. I love collecting new varieties with beautiful flowers and they make for such a great houseplant.

Gesneriads are a large family of more than 3000 tropical species that sport beautiful flowers and foliage. Many beloved blooming houseplants, such as African violets, are members of this group. Most gesneriads have similar growing needs and are perfect for indoor gardeners. Be sure to allow plants to dry between waterings, just like with many succulents. Over-watering can quickly kill them.

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African Violets are great for indoor gardeners who don’t have a lot of space but want to brighten up their home with flowers. African violets appreciate medium to bright indirect sunlight, such as you might find in a southern window. Hot afternoon sun can scorch them, but low-light conditions will leave them flowerless. Add an LED or Fluorescent grow lamp to boost blooms on your African violets if you don't have enough light indoors to keep them happy.

If you want to take advantage of the efficiency of HPS lamps but don’t want to compromise on light spectrum, you can (1) look for HPS lamps with enhanced performance in the blue spectrum, which are a great compromise, or (2) supplement your HPS lamp by combining it with some blue light from an MH or an LEC lamp, cool-spectrum, narrow-spectrum blue fluorescent tube, or blue LED.

If you are growing in an open space where natural outdoor light is present, such as a greenhouse or a room with windows, you can use HPS lamps alone to supplement the light spectrum and photoperiod—although the orange visual color of the light is less than aesthetically pleasing.

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The trick with taking cuttings, just as with germinating seeds, is to get the cutting to root before the tissue rots or dies. You can speed up the process by using supplemental rooting hormones, which are chemicals found naturally in plant tissues.

Rooting hormones are available in gel or powder form. Dip the base of your cutting into the rooting hormone, making sure to coat the entire tip, and place it in your rooting media or substrate.

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Photoperiodically, plants fall into three primary categories: long-day, short-day, and day-neutral. Plants that are not photoperiodic are day-neutral. In other words, long-day plants initiate flower buds when the days grow longer than their critical daylength. Short-day plants will initiate flowering when the days become shorter than their critical daylength.

It’s not the length of daytime, or light, the plants are responding to, but rather the period of uninterrupted darkness. The plant measures the amount of PR phytochrome in its system after a length of darkness. Therefore, long-day plants need short nights to flower, and short-day plants need long nights.

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Some lamps generate more light or more heat than others. Fluorescent lamps, CFLs, and LEDs are typically the easiest options for starting young seedlings, as they generate lower levels of heat than HID lamps and you can place them closer to your tiny plants.

If you site an HPS lamp a few inches away from young seedlings, the intense light and heat will quickly fry them. Once your seedlings grow up, you can employ more intense types of lighting.

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Here are a few key factors you should consider when choosing the type of lamp, or combination of lamps, you will use to grow your plants: the spectrum of light provided; that is, the balance of cool and warm colors and how much of each is provided; the usable quantity of light the lamp provides; the amount of heat output from the lamp; and the amount of light, or the number of hours, you intend to light your plants given their daylength requirements and the lamp’s energy efficiency.

As a general rule, the less expensive the purchase price of the light setup, the more expensive and less effective it is to run. You will get much better results if you provide the right intensity of selective or full-spectrum light that is specific to plant growth.

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A few orchid species require short-day photoperiods in conjunction with cool temperatures to flower, such as some species of Cattleya, Dendrobium, and potentially some species of Phalaenopsis.

For these types, you’ll need to combine cooler temperatures and shorter daylengths from midfall through winter, then lengthen your lighting period again in spring.

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