Surviving the Winter & Thriving Indoors: Subtropical and Tropical Plant Care tips

Okay, hear me out! I know this is a topic that has been on repeat for years, but thats for good reason. The truth is that it can be a tricky game at times to overwinter a lot of tropical plants indoors in Northern climates, especially for months at a time. Mostly because true tropicals lack a dormancy period. Think about it, in winter as the days shorten in northern latitudes there is very little day/night fluctuation in the tropics being closer to the equator. As a result, seasonal changes are more dictated by the availability of water (i.e., the wet and dry seasons) than length of day in the deep subtropics and tropical regions of the world. This is a critical clue for gardeners with tropicals during winter!

In this article we will discuss some general guidelines for your subtropical and tropical plants. Adapting these to your environment will help you keep those gorgeous ixora’s, palms, and even crotons happy during the chilly days of winter.

Speaking of chill… brrrrrr… let’s not! Instead, let’s take a look at 5 elements of winter care.

Understanding Subtropical and Tropical Plants:

Before diving into specific care tips, it's crucial to grasp the nature of subtropical and tropical plants. These plants originate from regions with consistently warm temperatures, high humidity and airflow, and ample sunlight. Recreating these conditions indoors during winter requires careful consideration of factors such as light, temperature, humidity, and air movement. Since most people don’t usually keep their houses in the 80’s with near 100% relative humidity - we need to find a happy medium.

1. Light Requirements:

Most subtropical and tropical plants are accustomed to receiving “bright, indirect” sunlight in their natural habitats. In other words, good early morning sun exposure and dappled shifting light throughout the day. Mimicking this light intensity indoors is vital for their well-being, but don’t worry - you don’t have to plant an oak tree in the middle of your living room to achieve this! During winter, when natural sunlight may be scarce, consider placing your plants near south or west-facing windows to maximize exposure. Sheer curtains can help defuse the light making it less likely to create hot spots. Supplemental artificial lighting (such as the type we discussed in our last article), can also be employed to ensure they receive the necessary light levels for healthy growth.

2. Temperature Control:

Maintaining a warm and stable temperature is crucial for subtropical and tropical plants. These plants typically thrive in temperatures between 65°F to 80°F (18°C to 27°C). Avoid placing them near drafty windows or doors, as sudden temperature drops can stress the plants, as can cool dry air or hot dry air come air conditioning systems. Consider using space heaters (WITH CAUTION) or adjusting the thermostat to maintain a consistent and comfortable environment for your indoor garden.

3. Humidity Management:

Indoor environments, especially during winter with heating systems running, tend to be drier than the native habitats of subtropical and tropical plants. To counteract this, increase humidity around your plants. Grouping plants together, using a humidity tray filled with water, or using a humidifier are effective methods to boost moisture levels. Regular misting of the plants with water can also provide a quick humidity boost. There are a myriad of humidifiers to choose from on the market, but they all basically fall into 3 categories: Sonicating, Vaporizing, and evaporative.

Sonicating humidifiers, also known as ultrasonic humidifiers, employ ultrasonic vibrations to generate a fine mist of water particles that is released into the air, increasing humidity levels in indoor spaces. These humidifiers typically consist of a diaphragm or nebulizer that vibrates at ultrasonic frequencies, breaking water into tiny droplets. Unlike traditional evaporative humidifiers, sonicating humidifiers operate quietly and are energy-efficient. They are a popular choice for maintaining optimal humidity levels in homes and offices, contributing to improved respiratory health and preventing issues related to dry air, such as irritated skin and static electricity. Additionally, sonicating humidifiers are available in various sizes and designs, making them versatile and suitable for different room dimensions and aesthetic preferences. One key important factor in using sonicating humidifiers is making sure the water that goes in is pure - in other words using distilled water is ideal. Hard mineral laden tap water or spring water can cause a while film to develop all over your room, so its best to use distilled or RODI water.

Vaporizing humidifiers, also known as warm mist humidifiers, produce humidity by heating water to create steam, which is then cooled slightly before being released into the air. These humidifiers are effective in adding moisture to indoor environments and are particularly useful during the cold season, as the warm mist can provide a comforting and soothing effect. Vaporizer humidifiers are often equipped with built-in heating elements or boil chambers that heat the water to a point where it turns into vapor. The warm mist they emit can be beneficial for relieving respiratory congestion and promoting a cozy atmosphere. However, they require careful handling to prevent the risk of burns, making them more suitable for use in areas where safety precautions can be observed. Tap water can be used, however calcium buildup can lead to burnout of the humidifier if it’s not cleaned regularly.

Lastly, we have evaporative humidifiers. Evaporative humidifiers operate by drawing dry air through a wet wick filter or other absorbent material. As the air passes through, it picks up moisture, and the humidifier releases this moistened air into the environment. The process mimics the natural evaporation of water, adding humidity to indoor spaces. These humidifiers are energy-efficient and suitable for larger areas, often accompanied by a fan to enhance air circulation. While effective, they require regular cleaning to prevent the growth of mold and bacteria on the filter. Evaporative humidifiers are a popular choice for maintaining comfortable humidity levels.

4. Air Movement:

Air movement is arguably the MOST overlooked yet critical aspect of indoor plant care, especially for subtropical and tropical varieties. In their natural habitats, these plants are exposed to gentle breezes that not only aid in pollination but also help to prevent issues like fungal diseases. Introducing controlled air movement indoors is essential for replicating these conditions.

The significance of air movement in indoor gardening becomes evident in its role in preventing fungal issues and strengthening plant structures. Stagnant air provides an ideal environment for fungal problems like powdery mildew and leaf spot diseases to thrive. Effective air circulation, facilitated by tools such as oscillating fans set on a low intensity, disperses excess moisture on leaves, hindering the development and spread of these diseases. Furthermore, consistent air movement plays a crucial role in strengthening plant stems, particularly vital for taller or vining tropical varieties prone to becoming leggy or weak in still conditions. The gentle breeze encourages the development of robust structures, reducing the plants' dependence on external support systems. Overall, promoting air circulation emerges as a key strategy in maintaining a healthy indoor garden by mitigating the risk of fungal infections and enhancing the structural integrity of the plants.

Air movement also plays a pivotal role in photosynthesis by facilitating the exchange of gases, such as carbon dioxide and oxygen, around plant leaves. A gentle breeze ensures a continuous supply of fresh carbon dioxide, a crucial component for photosynthesis, while also helping to disperse oxygen produced during the process. This improved gas exchange enhances the efficiency of photosynthesis, promoting healthier plant growth and vitality in indoor environments.

Practical Tips for Implementing Air Movement:

1. Use Oscillating Fans: Place oscillating fans on a low setting to provide consistent, gentle air circulation. Position them strategically to avoid direct drafts, ensuring a subtle breeze throughout the space.
   

2. Strategic Plant Placement: Arrange your plants in a way that allows air to flow freely around them. Avoid overcrowding, as this can impede air movement and create pockets of stagnant air.
   

3. Open Windows Periodically: On milder winter days, consider cracking open windows briefly to allow fresh air to circulate. Be cautious of extreme temperature changes and only do this when it won't expose your plants to cold drafts.
   

4. Avoid Overwatering: Seriously, chill out! Or dry out I should say! Remember what we discussed earlier in the article? Its dry season time! Excess moisture in the soil can contribute to overly high humidity levels indoors, pesky fungus gnats, root rot, and increase the risk of fungal issues. Ensure proper drainage and only water your plants when the soil feels dry when you stick finger in, and when the pot feels a bit lighter. If you followed our blog, you’ll have read about the use of charcoal in potting soil (see the article here). Charcoal additions in the potting medium can help with excess moisture and general root health. Just remember, you are far less likely to kill a plant from dryness than overwatering in winter. The truth is, they just don’t need as much water as we think they do. If you’re still unsure, consider a moisture meter!

5. Fertilization:

Lastly, but not least is fertilization in winter. While most tropical plants lack a dormancy, they likely aren’t going gangbusters indoors, but do they really need feed? The answer is - it depends.

Some species of orchid bloom during winter, so providing a weak fertilizers can be beneficial. Hibiscus rosa-sinensis for instance, is less likely to be putting on growth indoors and is quite content to just chill out in the corner. Generally speaking applying a 1/4 strength all purpose fertilizer during winter once a month is sufficient to get them through tough times. Just don’t go overboard and attempt to push tons of growth or blooms - its likely to cause more harm than good.

Caring for subtropical and tropical plants during the winter months requires a thoughtful combination of light, temperature control, humidity management, and crucially, air movement. By recreating the conditions these plants thrive in. Remember, the gentle dance of air around your plants not only prevents diseases and aids in photosynthesis, but also contributes to the overall health and resilience of your indoor garden. With these tips in mind, you can successfully navigate the challenges of winter and enjoy the beauty of your tropical oasis year-round.