To thrive, plants actively photosynthesize by transforming sunlight, air and water into energy for themselves. In the form of glucose, this energy creates and nurtures the stems, flowers, leaves, roots and fruits of virtually all plants and is necessary for them to grow.

When growing plants indoors, it can be difficult to get this balance right, especially when it comes to providing the proper amount of light required to maintain flourishing, happy specimens.

When a plant receives insufficient levels of light exposure, it can suffer greatly, as it can if it receives too much light—both situations are evidenced by marked changes in a plant’s appearance.

Even when positioned in the most southerly facing window, it can be difficult for indoor plants to gather the energy they need, and in winter months when sunlight is sparse, this can become even more of a problem.

Signs Your Indoor Plants Aren't Thriving

If your indoor plants aren’t receiving the right amount of light, you can be sure they will tell you. Instead of flourishing, their growth will become stunted enough to affect the plant’s outward appearance.

When growing any type of plant, it’s always worth keeping an eye out for telltale signs it’s not getting enough light. Look out for:

  • Falling leaves.
  • New growth that differs from previous growth. For example, the new leaves may be smaller and not as vivid in color, and new stems are likely to be elongated, making the plant look leggy.
  • The plant will be visibly growing towards the light, more so than it would otherwise.
  • Leaves may cup upward.

By the same measure, plants can also suffer due to overexposure from light and again there will be some telltale signs:

  • Leaves will look washed out and faded.
  • Leaves will become dry and will likely fall off.
  • The plant may wilt come mid-day when it’s receiving the most light.
  • Dry, brown and sometimes scorched patches may appear on leaves.

Identifying the key signs your plants aren’t getting the right amount of light are the first steps in nursing them back to health.

Supplementing Natural Light with Artificial Lighting

While in some cases altering the amount of light your plants are receiving is as simple as moving them to a sunnier windowsill or pushing aside a curtain, it’s not always that easy.

Many of us have more indoor plants than we do available window space, while other people may only have north-facing windows, if any spare windows at all, meaning they must look for other methods to ensure plants prosper.

Where your plants are faced with a lack of natural light, it’s possible to supplement or even replace it with artificial lighting to maximize the garden’s potential. Artificial lighting can provide a reliable source of light for plants throughout the home and in many cases is a vital addition for growing healthy, happy plants.

Plant Growth and Grow Light Color

For your plants to grow properly with the aid of artificial lighting, the light they receive must imitate natural sunlight, which contains a full spectrum of colors. The two colors within this spectrum most important for plant growth are blue and red.

Blue light regulates plant growth, making for a stockier plant, while red light stimulates flowering and vegetative growth. Together, these two colors ensure plants prosper. Should one color outweigh the other, however, it can have adverse effects on plants. For example, if plants receive too much red light they will be leggy and sparse.

The general lights in most homes contain primarily green and yellow light, colors that are of little use to plants and do not promote photosynthesis or provide a suitable substitute for sunlight. That’s why there are several types of artificial lights on the market that are specifically designed to aid and ensure the growth of plants. These lights make use of Photosynthetically Active Radiation (PAR).

Choosing an Artificial Light Source

Different types of bulbs emit different types of light, a different spectrum of colors and varied intensities, meaning that not all of them are suitable for each type of plant. Knowing the specific light requirements for your indoor plants will benefit you when trying to determine what type of artificial light will aid your plants best.

For indoor plants that require only low levels of light or merely a little extra supplement, incandescent lamps are suitable. While the bulbs emit primarily red light, which only meet half of the plant’s needs, they will suffice if you only require a few hours of additional illumination.

Incandescent bulbs do, however, have the downside of burning hot, which reduces humidity and creates a dry environment for plants, potentially burning their leaves. It is vital you take this into account and make allowances when setting up incandescent lamps.

Regular fluorescent bulbs provide a cooler environment for plants while producing up to three times more light than an incandescent bulb of the same wattage. They primarily produce blue light, which on its own cannot sustain plants. To combat this, consider using a two-bulb fixture that allows you to combine the light from both fluorescent and incandescent lights to create a full spectrum of color.

Perhaps a better alternative for promoting the healthy growth of indoor plants is a full-spectrum fluorescent grow bulb. They’re designed specifically for this use and come with all the advantages of regular fluorescent bulbs, along with a few of their own. Full spectrum fluorescent grow bulbs mimic sunlight and are calibrated to replicate approximately 94% of the light spectrum, making them a highly suitable choice for illuminating indoor plants.

If you need to illuminate a large area, you might consider using metal-halide (MH) and high-pressure sodium (HPS) lamps. These lights provide the best spectrum of colors for aiding plant growth. They emit a strong white glow, which is not always suitable for standard homes.

At home, a concealed area is recommended for optimal performance of these lights, but they are a top choice for bringing artificial light to indoor farms and other industrial endeavors.

Light-emitting diode lamps (LEDs) also provide a sufficient amount of red and blue to indoor plants, without the strong white glow and without the danger of overheating. The technology is relatively new, with many growers praising its effectiveness.

Regulating Artificial Lights

While the use of artificial lights enables you to provide your indoor plants with ’round the clock light, it’s worth noting that this can be extremely damaging to them. The majority of plants require between 12 to 16 hours of light per day to flourish, and 8 to 12 hours of total darkness, which regulates growth. This can be expressed as the plant's preferred photoperiod.

Allowing plants too much light will cause the color to fade, excessive dryness of the soil and drooping or wilting of the flowers and leaves. Similarly, allowing plants too little light will result in leggy, spindly growth. Again, the amount of light required varies from plant to plant so it’s worth checking what light intensity your specific plants need.

Regulating the light plants receive and keeping it to roughly the same time slot each day will help them flourish year round. Many people find the use of an automatic timer helpful when attempting to regulate the periods of light and darkness their plants are exposed to.

Consider All Your Options

There are many advantages to providing your indoor plants with artificial light sources, promoting healthy growth being only one of them. The use of artificial lights allows you to essentially control day length for your plants, which in some cases can stimulate out of season changes and kickstart the flowering stage.

For example, left to grow naturally, poinsettias only flower in winter when there is 11 hours of daylight or less, something artificial lighting can mimic at any time of year. Similarly, come the winter months when the intensity of natural light is much lower and the days grow shorter, the use of artificial light can also promote the blooming of what are usually summer flowers.

There are downsides to the use of artificial lights, too. Plants growing with the aid of artificial lights, even fluorescent ones that are relatively cool, tend to dry out quicker than they might otherwise, so it’s important you’re aware of this flaw and compensate for it.

You will also need to take into account the fact you’ll need to alter the height of your artificial lights to compensate for plant growth, as having them too close is likely to scorch the leaves. This is easily remedied with the aid of an adjustable fixture or lamp.

As for indoor plants that are grown in natural light, you should rotate those grown with the aid of artificial lights on a weekly basis to ensure an even distribution of light, thus helping your beloved plants prosper and flourish.

Determining the most suitable indoor lighting is one of the most important steps in starting an indoor garden. Be sure to ask your indoor garden retailer for more advice on lighting options, or check out Maximum Yield's lighting article library for more advice on optimizing your grow lights.