A Comprehensive Guide to Gardening in Humid Climates

Living in humid climates my whole life, I know what it’s like to manage high humidity in the garden. In as few words as possible—it’s not fun. Not only is it tough to enjoy the gardening process when the air is muggy outside, but it’s also difficult to manage the extra moisture and diseases that come with it.

I also wouldn’t want to live anywhere else. My garden feels like a tropical paradise, and higher humidity makes it much easier to grow the plants that I love. The orchids are always happy, I have several fruit trees that almost take care of themselves, and leafy plants grow incredibly quickly when the weather is warm.

There are upsides and downsides to moisture in the air, but it’s what you do with it that counts. So if you’re in the same boat, these are the lessons I’ve learned to make the most of it.

How Humidity Affects Plants

Temperature is usually the primary concern among gardeners when it comes to climate and the weather. But humidity also has an impact on plant health, and activity in your garden throughout the seasons.

Some plants appreciate plenty of moisture in the air. It affects transpiration and water loss, preserving leaf moisture and boosting growth. High humidity has the opposite effect for plants that have adapted to dry climates. It impacts gas exchange in these species, slowing photosynthesis. Slow photosynthesis leads to slow growth and poor performance overall.

Most plants are happiest in the moderate humidity range, around 40% to 60%. High humidity is typically about 70%, while low humidity is 30% or lower.

The Good, The Bad, and the Ugly

High humidity has a big impact on your garden. Some of the results are good, but many are bad or even dangerous for certain species.

The benefit of living in a high-humidity climate is the range of plants you can grow. If you’re looking to start a lush, tropical jungle in your backyard, you will have no problem keeping your plants happy. Higher humidity is also generally better for plant growth than excessively low humidity.

However, it’s important to consider humidity levels with temperature. Extra moist air plus high temperatures create a tough environment for plants to thrive. You need to be careful about which plants you choose if frequent heat and humidity are common in your region.

The biggest downside is the increased risk of disease. Many fungal pathogens thrive in humid environments and spread quickly if not controlled early. While some may not be harmful early on, several of these fungal diseases can wipe out plants and become a continuous issue throughout your garden.

How to Garden in Humid Climates

The unfortunate reality is that we can’t change the weather, but there are ways to manage muggy growing conditions.

Manage Your Soil

Gardening in high humidity starts with thinking about the foundations of the garden—soil. You may think that humidity only impacts the moisture in the air, but it also has an influence on moisture in the soil, too.

When the air is dry and temperatures are high, moisture evaporates from the soil quickly. When there is already plenty of moisture in the air, and it is close to saturation, less moisture evaporates from the soil over time. In other words, higher air moisture also means that the soil holds onto moisture for a little longer than you may expect.

To account for this extra moisture-holding capacity, it’s important to check your drainage. Humidity doesn’t have as much influence as other soil characteristics, but if your soil already holds more moisture than you would like, muggy air only compounds the problem.

Manage your soil by regularly checking drainage and amending areas where water pools over time, particularly during humid seasons. Or, pick species that grow better in moisture-holding clay-based soils to avoid issues with root rot in sensitive plants.

Choose the Right Species

Once you’ve got your soil right, carefully consider what you’re going to plant in it. As much as we all want to grow our favorite crops and ornamentals no matter the conditions, it’s far better to stick to garden species that love high humidity, rather than deal with constant growth problems fighting against it.

In the edible garden, the options are a little more limited. One of the most commonly recommended vegetables for humid climates is tomatoes, but I must go against the crowd and say I’ve had endless problems in my garden.

Tomatoes are far more susceptible to a long list of diseases in muggy climates, creating more work and increasing risk to other plants, too. They don’t mind the moisture, but be prepared to battle diseases throughout the season.

Pay Close Attention to Spacing

Fungal disease is one of the biggest concerns in high-humidity gardens. It’s always important to practice disease-prevention strategies, but even more so when it is humid. This starts with paying close attention to spacing at planting time to avoid overcrowding.

Lack of airflow due to overcrowding, combined with extra moisture in the air, creates the perfect environment for fungal diseases to settle in. Muggy conditions are also present when there is little wind, making the lack of airflow even more prevalent.

When sowing seeds or transplanting, always give your crops enough room to grow without overlapping. A little extra space goes a long way.

Prune Regularly

If you have planted a little too close together, pruning often will save the day. Pruning is also a great tool for species with dense leaf growth that may be restricting airflow between stems. Cutting back will improve airflow around the plant, making fungal disease less likely.

Before you start pruning, clean and disinfect your garden tools. If you notice any signs of disease while trimming, disinfect your shears between cuts to avoid spreading the problem to healthy neighboring shrubs or trees. You don’t need to cut back heavily—only remove dense areas to give the plant some breathing room.

Water in the Morning

Standing water droplets resting on foliage or flowers for long periods greatly increases the risk of disease in the garden. That’s why you often hear recommendations to never water overhead and water in the morning. This is always a good practice, but it becomes essential in moist, muggy climates.

Watering in the morning gives water droplets time to evaporate throughout the day. Watering in the afternoon (or worse, in the evening) when evaporation rates are already slower will keep excess moisture around leaves and stems, causing a long list of problems.

Watering in the morning is also better for plant health, ensuring the roots have enough moisture to keep the plant happy and less stressed in sunny and hot conditions.  

Look for Diseases

Even if you employ these prevention strategies, disease is still a risk in the garden. Gardeners in high-humidity regions need to be extra vigilant, regularly checking for signs of disease and tackling them as soon as possible. Many diseases can’t be cured once they settle in, so management and prevention are essential to a healthy garden.

Various fungal diseases are prevalent in muggy areas. These include mold, mildew, and blight. The signs of infection differ depending on the specific pathogen, but issues like spotted leaves, stunted growth, or visible fungal growth are all cause for concern.

As soon as you spot a problem, remove the affected leaves, fruits, or stems and discard them. Don’t compost any diseased materials, as this will spread the issue. After trimming, apply treatments if needed based on the disease you’re dealing with, and keep a close eye on your crops for signs of spread.

Harvest Early

Due to the higher risk of disease, one way to protect your harvests in edible gardens is to harvest early. This could mean picking fruits that ripen off the plant as soon as possible to ripen indoors or harvesting and storing any produce when it’s ready in a safe spot.

Leaving fruits outdoors risks mildew and mold before you get a chance to harvest and enjoy the fruits of your labor. Stay on the safe side and harvest as soon as you can.