A Place in the Sun: Acclimating houseplants to sunlight

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If you want to move your houseplant to a brighter situation, you must gradually introduce it to its new surroundings. This guide explains how to acclimate houseplants to brighter sunshine, either inside your house or outdoors.

When would you need to acclimate plants?

There are two occasions on which you would need to acclimate your plant to brighter sunshine. One is when you place houseplants outside for the summer. Your sun-loving houseplants will benefit from the maximum natural light, natural airflow, and higher humidity. Your plants will not accumulate household dust, boosting transpiration and photosynthesis, while rainwater is generally more beneficial than tap-water.

After a summer outdoors, your plant will exhibit increased growth and more luscious foliage. This applies particularly to cacti and other succulents. On the other hand, many tropical plants like palms and ficus will prefer filtered light. These species may still benefit from summers outdoors, but you will need to find a shady outdoor patch for them perhaps facing east or west.

Another time you would need to acclimate is whenever you move your plant to a brighter situation inside your home.

Why do you need to acclimate plants to brighter sunlight?

Plants must get used to processing more sunlight gradually. Even if your plant is sun-loving, any sudden move to a sunny spot may burn its leaves. This is because plants adjust their photosynthetic apparatus according to the environmental conditions in which they find themselves.

Low light conditions will trigger the plant to increase light-harvesting processes. If plants are happily harvesting light more efficiently under low-light conditions, it may take up too much light if placed suddenly in brighter situations. The shock of sudden direct sunlight may damage the plant’s development permanently.  

Acclimating your houseplant outdoors

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Wait until night-time temperatures do not drop below 50 degrees Fahrenheit (10 degrees Celsius) before placing your houseplants outside.

Acclimate plants to direct sunlight over a few weeks.

At first, place the plant in a slightly brighter situation for two hours a day over a period of four days. For the next four days, place the plant in its new situation for four hours a day, returning it to its original situation the rest of the day. For four days after that, place the plant in the new situation for six hours a day. Next, you can place the plant in the new situation for eight hours a day for four days. The acclimatization process will be complete, and you can leave the plant outside 24/7.

While you are increasing the number of hours your plant is spending away from its original situation, you should also be introducing the plant gradually to the target light intensity. Never move a plant from shade into direct sunlight immediately, even for brief periods.

If you are trying to acclimate the plant to your garden, place it under the foliage of a larger plant or in a partially shaded area at first. Once the plant is spending eight hours a day outside, you can place the plant in its new light situation.

Acclimating your houseplant to a brighter spot indoors

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The same principles for acclimating plants outside apply when acclimating plants to a brighter indoor spot. Move plants into increasingly brighter spots for longer hours every four days.

If you are acclimating your plant to a brighter situation inside your house, start by placing the plant 4 feet away from a bright window. Then, move the plant two feet closer to the window each time you increase the hours it spends in its new spot.

A few inches or feet can make a huge difference in the amount of light that the plant receives. A plant 2 feet away from a window will receive three-quarters less light than if it were directly next to the window. As a rule, light intensity decreases by the square of the distance from the light source: 2 feet away and it receives 1/4^th the light. 3 feet away and it receives 1/9^th of the light. 4 feet away and it receives 1/6^th of the light.

If you are moving your plant around in your home, consider the new light situation carefully against your plant’s light needs. The orientation of the window is not the only factor to bear in mind: its immediate surroundings may alter the actual sunlight that your plant will receive. A south-facing window shaded by high trees may still block the high-noon sun during summer, while letting in more hours of direct sunlight when the sun is low in the sky during winter.