Whether you grow your vegetables in a greenhouse or herbs in a raised bed, maintaining optimal growing conditions on your allotment can be the difference between a thriving harvest and a disappointing one. While growers widely understand the importance of sunlight, water, and soil quality, many gardeners forget another key factor for growth success… humidity.
A hygrometer is a weather monitoring instrument that measures the level of moisture content in the surrounding air, which is also known as ‘relative humidity’ (RH). Although they are often used in indoor spaces and greenhouses, hygrometers are also useful on allotments, where understanding how outdoor humidity and your allotment's microclimate can be the secret to your growing success.
Monitoring humidity on an allotment is crucial for successful gardening, particularly when combined with monitoring conditions such as temperature, rainfall, and air pressure.
Here are a few examples of how humidity levels can impact the plants and crops on your allotment:
The right humidity is essential for getting seeds off to a strong start. 75-95% relative humidity (RH) provides the moisture a dormant seed needs to germinate. Without it, germination rates can drop, and seedling growth may be reduced. However, excessive humidity can encourage damping-off disease, where young seedlings collapse due to fungal infection.
Humidity affects a plant’s ability to absorb water and nutrients through transpiration. The process of releasing moisture through its leaves. High humidity slows transpiration, while low humidity speeds it up, leading to dry and wilting foliage and nutrient deficiencies. Some plants, particularly those from humid climates, are susceptible to changes in moisture levels.
Moist conditions create the perfect environment for fungal diseases such as mildew and root rot. Other problems, like Botrytis (grey mould), can occur when humidity suddenly drops and temperatures rise. Monitoring RH helps you spot and prevent these issues before they take hold.
Humidity also influences how quickly your soil dries out, which in turn affects your watering routine. Low humidity means plants may need watering more frequently, while high humidity slows evaporation, meaning you can often ease off, especially after rainfall.
When humidity levels remain too low or too high for long periods, plants can become stressed, making them more susceptible to pest damage. Keeping RH within an ideal range supports stronger plants that are better able to resist pests and maintain healthy growth.
Hygrometers are like having a weather-wise friend on your allotment, always ready to tell you exactly how humid it is. This is important when it comes to keeping plants happy and healthy. By providing accurate readings at a glance, hygrometers help you stay ahead of potential problems such as wilting leaves, mildew, root rot, and even unwelcome pests.
The beauty of a hygrometer is that it helps you understand your allotment’s microclimate, as not all parts of your allotment will behave the same; a shadier patch will hold moisture for longer than an area consistently exposed to the sun. Understanding this means you can make smarter gardening decisions, such as avoiding over- or under-watering, planting humidity-loving crops together, or grouping more sensitive plants where you can keep a close eye on them. You can also provide protective measures against harsher elements such as planting in a greenhouse, covering your sensitive plants during periods of extreme weather, and ensuring the location planted provides your plants with the best chance of survival.
If your allotment has a greenhouse, a hygrometer becomes even more valuable. Helping you accurately monitor and adjust humidity levels to create the perfect conditions for whatever you’re growing. Need more moisture? A quick misting or a few open trays of water can do wonders. Too much? You can open any vents and windows, or even crack the door open to allow free-flowing air to enter the greenhouse.
You don’t need to be a weather expert to get started with your hygrometer. Here are some quick tips for hygrometer usage on your allotment:
· Hang your hygrometer as close as possible to your growing area or in areas prone to humidity build-up, such as greenhouses and polytunnels.
· Avoid placing your hygrometer in direct sunlight as it can affect the accuracy of your readings.
· Check your hygrometer regularly to keep an eye on daily patterns and extremes.
· We’ve spoken about ideal humidity levels for seed germination; however, many plants and crops tend to thrive within a relative humidity level between 40% and 60% as levels outside of this range can often lead to issues such as mould, mildew, and root rot.
At ClimeMET we have a selected range of hygrometers, ideal for both indoor and outdoor use. Let’s explore the collection:
CM3505 Masons Wet and Dry Bulb Hygrometer
The Mason’s Wet and Dry Bulb Hygrometer is perfect for your allotment because it combines timeless craftsmanship with practical functionality. It features two thermometers, with one wrapped in a wick that dips into a refillable water tank, allowing you to measure relative humidity like a gardening meteorologist using a simple conversion table. The weatherproof casing and protective roof means our hygrometer can handle the British summer showers, while the mounting hooks make it easy to hang on a fence or post around your allotment. Our hygrometer has a beautifully illustrated backplate, inspired by native hedgerow flowers, that adds charm to your plot while helping you grow smarter.
Our Hygrometer Dial is the perfect blend of style and practicality for allotment life. With its self-contained, wire-free design and weatherproof casing, it displays real-time humidity levels on a clear and easy-to-read dial, no fuss, providing reliable readings. Accurate within ±5% RH and covering the full 0–100%RH range, our hygrometer dial gives you the confidence to monitor your microclimates. Our hygrometer dial can be hung both indoors and outdoors, making it a great choice for greenhouse gardeners. You can also customise your dial, great for gifting or marking your plot, adding personality while ensuring a successful growing season.
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