This indoor plant light guide is contributed by Sarah Gerrard Jones, an expert on houseplants.

All plants need light to survive. In simple terms light is essential for your plants to create food. As humans, we can survive only for some time without food and the same applies to plants. The amount of light plants need varies from species to species but ALL plants require some light during the day.

So, why is that? We’ve all heard about the process, called photosynthesis, which is impossible without some sort of source of light. To be able to photosynthesise, plants require plenty of light during the day, water, as well as oxygen. These elements help your house greenery (and any plant) to create energy. The plant converts these essential-to-life ingredients into carbohydrates, which are the prerequisites for its undisrupted growth and production of seeds. If the plant is not sufficiently exposed to light, it will slowly die, due to the lack of enough carbs, once the plant has resorted to and depleted its reserves. Fortunately this plant light guide will give all the important information, so you plants would never be hungry for light ever again.

Table of contents:

My advice for prospective plant parents is to do your research about where your plant originates from and try and place it accordingly in your home. For example a cactus that originates from the desert will need plenty of sunlight so don’t place it in a dark spot. A ferns natural habitat is a damp, shady spot so don’t sit it in the brightest area of your home. Do your homework to avoid a plantastrophy.

The Biology

Now then, back to the basics of photosynthesis.

As we’ve mentioned above, when light energy gets absorbed by the plant, more energy is generated in the form of nutrients, which the plant thrives on. This process takes place in specific cells, called chloroplasts. Interestingly, the plant can adapt easily to the amount of light they get with the help of these cells. So, if light is reduced, the concentration of chloroplasts will also change so that the plant can accommodate itself to the new conditions. This process is known as acclimatisation. It means that sun-loving plants can “learn” to thrive in semi-shade and vice versa, shade-tolerant plants can adjust to an environment of a more intense sunlight exposure.

As we can see, life on Earth relies on the key aspect of plants’ amazing ability to transform sunlight into energy that is renewable (or reusable) in one way or another. Animals survive on plants and other animals feed on plant-eating creatures, so energy is a constant and a transformable source to life.

How to define the light source?

Work out the directions your windows are facing. In the northern hemisphere South facing windows will get the most amount of light, North facing windows the least. East and West windows will get a moderate amount of daylight. There are different plants that will be happy in each of these locations, but there aren’t plants that will survive with no light and few which will live in very dark areas of your home.

Types of light

Understanding the different types of light will help you decide where to place your plant in your home.

  • “Bright, indirect light” or “full sun” – will be found within 2 foot of a south or southwest facing window. Don’t place your plants too close to this type of window where they can be scorched by the sun.
  • Medium light“– an east or west facing window, where the sun only shines for part of the day.
  • “Low light” or “shade loving” – means no direct sun will reach your plant. These will be areas set at least 3 feet back from windows. Or windows that are shaded for the majority of the day by buildings or trees outside. North facing or northeast windows are generally considered ideal for plants with lower light requirements.

Well, you need to also comprehend what these types of light conditions mean for your plant.

For instance:

  • Low-light plants grow in Nature in damp, shady places, usually underneath bushes and large plants or under trees. As shade-loving plants take time to dry out, they do not require frequent watering. So, always check the soil before your reach for the watering can. Also, these types of plants are not that fussy when it comes to living under artificial light conditions. So, they are ideal to be placed in an office environment or in another type of workplace.
  • Medium-light plants, as we mentioned earlier, will thrive in well-lit areas but not under direct sunlight. To get a clearer picture, a couple of fluorescent light bulbs will suffice for such plants to feel comfortable. Again, medium-light plants don’t dry out fast, so you should touch the soil before you decide to water them.
  • High-light plants need plenty of light, of course. As well-lit areas around your home, such as south-facing windows, are also the warmest, you will need to consider checking the soil regularly, because the plants can dry out in no time. And there’s nothing easier than forgetting to water them when the plants most need it

How to find out what type of light do I have at home?

If you’re unsure about the type of light you have why not do this simple shadow test. On a sunny day, place a sheet of white paper on the spot where you intend to place your plant. Hold your hand about 1ft (12”) above the paper. If you can see a clearly defined shadow, this spot receives bright light. If the shadow is fuzzy, but still recognizable as a hand, the spot receives medium light. If you only see a very faint shadow and you can’t make out the different fingers, this area only receives low light. Finally, if you can’t make out a shadow at all, you know that spot is deep shade, and isn’t a good place to keep most houseplants.

On the whole, the shadow test is a great way of assessing the light conditions in your home. But it doesn’t hurt to know that three main factors play when it comes to evaluating light, with regards to growing or looking after plants.

  • Light duration – it refers to how many hours of light your plant gets in 24 hours;
  • Light quality – we associate light quality with the specific colour of light and its wavelength (sunlight contains all the colours of the spectrum, but plants thrive by using blue light in their vegetative state to encourage foliage growth and red to develop their buds);
  • Light intensity – it is the brightness of light, which is measured in foot-candles (or the amount of light a 1 sq.ft surface gets if located 1 ft away from a source of light).

How does artificial light work with houseplants?

Normal artificial lighting in our homes and offices does not provide a plant with the right type of light it needs to survive but you can invest in grow lamps and lights that simulate the correct type of light for indoor plants to grow and thrive. These can be a good option if you’d like to have plants in a dark spot in your house or to maintain consistent levels of light through all seasons.

Winter season and light

The amount of light we get in our homes drops dramatically in winter. A plant that has been happy throughout spring and summer may start to show signs of lack of light. Stems may become weaker and more elongated than normal, leaves may be smaller and paler than usual. It’s time to move your house plants to a brighter spot in your home, or move them closer to the window to give them the best chance of surviving the lack of light during the winter months.

tip

Just like surfaces plants also collect dust. A layer of dust on the leaves of houseplants will block sunlight and reduce the plant’s ability to photosynthesize. Give them a regular clean to make sure they are able to absorb the maximum amount of light.

Identifying Problems

As we said, if a plant is not getting light as it should or it has been overly exposed to direct sunlight, there are tell tale signs you should be looking for, in order to remedy the situation. Here are some indicators that your plants have suffered from the wrong lighting conditions:

Insufficient light

  • Slow growth and spindly appearance;
  • Leaves have become yellow, ready to fall;
  • Weak new leaf growth (leaves are small in size);
  • Scarce blooms.

Insufficient light

  • Dry leaves, which look shrivelled;
  • Fading, pale or drooping leaves;
  • Flowers are dying quicker than they should;
  • Stems feel limp to the touch.

My top 10 plants for shade

Bright light/full sun

  • Jade Plant (Crassula ovata)
  • Euphorbia Trigona (Euphorbia trigona)
  • String of Pearls (Senecio rowleyanus)
  • Aeonium –the darker variety (Aeonium)
  • Aloes (Aloe)
  • Desert cacti (Carnegiea gigantea)
  • Haworthias (Haworthia)
  • Crotons (Croton)
  • Opuntia (Opuntia)
  • Madagascar Palm (Pachypodium Lamerei)

Medium light/semi shade

  • Spider Plant (Chlorophytum comosum)
  • Dieffenbachia (Dieffenbachia)
  • Snake Plant (Sansevieria Trifasciata)
  • Zamioculcas Zamifolia or ‘ZZ’ (Zamioculcas)
  • Ponytail Palm (Beaucarnea Recurvata)
  • Pothos (Epipremnum aureum)
  • Monstera Deliciosa (Monstera deliciosa)
  • Burmese Fishtail Palm Philodendrons
  • Alocasias (Alocasia)

Low light/shade

  • Aspidistra – Cast Iron Plant (Aspidistra)
  • Ferns (Tracheophyta)
  • Chinese Evergreen (Aglaonema)
  • Arrowhead Vine (Syngonium podophyllum)
  • Maranta – Prayer Plant (Maranta)
  • Corn Plant (Dracaena fragrans)
  • Ficus Pumila (Ficus Pumila)
  • Peace Lily (Spathiphyllum)
  • Parlor Palm (Chamaedorea elegans)
  • Dracaena Surculosa (Dracaena surculosa)

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Did you like it? Do you have experience with growing houseplants at home? Let us know in the comments below!

  • Last update: November 19, 2019

Posted in Garden Advice, Plants in the UK

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