How to Assess Your Balcony’s Growing Zone & Microclimate

How to Assess Your Balcony’s Growing Zone & Microclimate


When starting a design one of my first questions is always “What is the microclimate like?” While national or regional growing zone maps provide a broad overview, the microclimate of a balcony can differ. Whether it’s affected by adjacent structures, elevation, or the materials from which it’s made, getting to know your balcony’s specific zone and microclimate characteristics will optimize plant health and yield. In this article we will explain how to determine your balcony’s microclimate.

Meditation: The Mission-Critical Connection

Before you gather any balcony data, set aside a special moment for rumination. Spend at least 10 minutes in quiet reflection on your balcony, deeply immersing yourself in the ambiance. This step is paramount. Why? Because your overarching aim is to cultivate a space that genuinely resonates with you. To truly accomplish this, you must start by forging a connection with the balcony in its raw, unaltered state. This introspective connection guides you in understanding what exists and intuiting what “feels right” for its transformation.

When you engage with your environment in such an intimate manner, you open yourself up to discoveries you might have otherwise overlooked. Perhaps you’ll notice sections of the floor that are surprisingly warm, hinting at where you might position sun-loving plants. Do you feel a tad too exposed? Consider introducing vines and a trellis to create a cozy sense of privacy. As you sit, the aromatic scent of focaccia might drift over from a neighbor’s balcony, sparking the idea to plant fragrant rosemary.

The insight you stand to uncover by simply being present on your balcony is singular. Let your senses steer your reflections, and you’re guaranteed to unearth something invaluable.


The Factors Influencing Your Balcony’s Growing Zone

  1. Sun Exposure

    The amount of sunlight your balcony receives daily impacts its temperature range. A south-facing balcony often gets more sun, making it warmer, while a north-facing balcony may remain cooler and shaded. Beyond just determining the growing zone of your balcony, this is also good information for you to know because it will help you select plant varieties that are more likely to thrive given your sunlight conditions.

    Rule of Thumb: Note down the times the sun rises and sets on your balcony over a week. This will give you an average sunlight duration.

  2. Surrounding Structures

    Adjacent buildings, walls, or trees can create shade, reflect sunlight, or block prevailing winds. They can also retain heat, radiating it during the night.

    Rule of Thumb: Observe neighboring structures throughout the day. Are they casting shadows? Reflecting sunlight? Make notes to understand patterns.

  3. Elevation & Floor Material

    Higher floors are often windier and can have slight temperature variations compared to the ground. The material of the balcony floor can also influence heat retention and radiation.

    Rule of Thumb: If your balcony is tiled or concrete, it may retain more heat. Wooden floors might not retain as much heat.

  4. Barrier & Protection

    Walls, railings, or screens can protect plants from wind, making the balcony’s microclimate different from open areas. They can also provide shade or reflect light.

    Rule of Thumb: On a windy day, check if your railings or screens are offering protection. Feel for temperature differences in shielded versus exposed areas.

  5. Air Circulation & Moisture

    Balconies sheltered from wind may have more humidity, especially if water doesn’t evaporate quickly. Proper air circulation prevents fungal diseases in plants.


Combine Hardiness Zone Knowledge with Balcony Observations

  1. Base Zone Assessment: Start with the basic hardiness zone designated for your location. This gives you a foundational understanding of the general climate and the minimum average temperatures you can expect during the colder months. Now that you have an understanding of your general hardiness zone from the USDA or Canadian Plant Hardiness Maps and a detailed grasp of your balcony’s unique conditions, it’s time to meld these two sets of information. ( I have linked official resources for the USA and Canada but these maps are also available in other countries).
  2. Microclimate Adjustments:
    • Temperature: If your balcony observations, especially with the aid of a min-max thermometer, suggest consistently higher or lower temperatures than the general area, adjust your zone accordingly. For instance, if you’re in Zone 6a but your balcony never goes below the minimum temperatures of Zone 6b, then your balcony likely aligns more with Zone 6b.
    • Sunlight & Shade: The hours of direct sunlight and periods of shade will determine how much heat and light your plants receive. A balcony with prolonged direct sunlight may support plants from a slightly warmer zone.
    • Wind & Air Circulation: If your balcony is particularly windy or sheltered, this can influence how plants experience cold. Windier balconies might need plants that can withstand cooler conditions, while sheltered ones might lean warmer.
  3. Holistic Zone Estimation: Combine your base zone with the microclimate adjustments to estimate the best zone fit for your balcony. This holistic assessment ensures that you aren’t just relying on broad geographic data but tailoring your plant choices to the exact conditions on your balcony. To get a better understanding of this process check out these illustrative examples.

Remember, gardening is as much art as it is science. Your holistic zone estimation gives you a starting point. Over time, as you observe how different plants perform on your balcony, you’ll be able to refine your understanding and make even more informed choices in the future.

Technology to the Rescue

I highly recommend a min-max thermometer, this will allow you to see the high and low tempurture in a given time period. In order to get a solid understanding of your balcony’s microclimate you will have to track these variables multiple times per day (and your data will only improve as you continue to collect more data over the course of the year). While it is an option to keep a dedicated notebook or app to help you track your balcony’s microclimate, I think a small weather station is a great tool that saves a lot of time. Here are my go to tools!


By understanding your balcony’s unique growing zone, you not only enhance plant growth but also expand the range of plants you can successfully nurture. While the journey requires observation, a touch of technology, and understanding broader regional climates, the end result—a thriving, lush balcony garden—is well worth the effort.

Now that you have this information, the next step is to create a microclimate blueprint on paper. This will ultimatly be the foundation of any designs you create. For a step-by-step guide on how to create this blueprint check out From Observations to Diagrams: Plotting Your Balcony’s Microclimate.