How Often Should You Water A Greenhouse?

In the realm of aspiring gardeners, the question of how often to water a greenhouse remains a tantalizing mystery. As the gentle rays of the sun caress your plants, ensuring they thrive in their cozy haven, it’s quite normal to wonder just how frequently you should shower them with your watering can. With an understanding of the delicate balance needed to maintain optimal moisture levels, this article will shed light on the secrets of greenhouse irrigation, empowering you to create a flourishing oasis of greenery within the confines of your own garden. So, let’s embark on this horticultural journey together and unlock the key to successful greenhouse watering.

Factors Affecting Watering Frequency

Type of Plants

The type of plants you are cultivating in your greenhouse is an important factor in determining the watering frequency. Different plants have different water requirements, with some being more drought-tolerant and others needing consistently moist soil. Researching the specific watering needs of each plant species is crucial for maintaining their optimal health and growth.

Stage of Growth

The stage of growth of your plants also plays a significant role in determining how often you should water them. Seedlings and young plants typically have more delicate root systems and require more frequent watering to ensure their roots stay moist. As the plants mature and develop stronger root systems, the watering frequency can be reduced, as they can absorb water more efficiently.

Size of Containers

The size of the containers in which your plants are potted affects the watering frequency as well. Smaller containers tend to dry out more quickly since they have limited soil volume to retain moisture. On the other hand, larger containers with more soil can hold moisture for longer, reducing the need for frequent watering. Consider the container size when establishing your watering routine.

Type of Growing Medium

The type of growing medium you use for your plants, such as soil, peat moss, or coco coir, also affects watering frequency. Different growing mediums have varying water retention capacities. Sandy soils, for example, drain water quickly, while heavy clay soils hold onto moisture for longer periods. Understanding the characteristics of your growing medium will help you adjust the watering frequency accordingly.

Temperature and Humidity

Temperature and humidity levels in your greenhouse have a direct impact on the rate at which plants lose moisture. High temperatures and low humidity can lead to faster evaporation and drying of the soil, requiring more frequent watering. Conversely, cooler temperatures and higher humidity levels reduce water loss, allowing for less frequent watering. Monitor the greenhouse climate and adjust your watering schedule accordingly.

Seasonal Changes

Seasonal changes also influence watering frequency. During the hot summer months, when evaporation rates are higher, you may need to water more frequently to compensate for the increased water loss. In cooler seasons, such as fall and winter, the reduced evaporation rate may result in reduced watering needs. Stay attentive to the changing seasons and adjust your watering routine accordingly.

Greenhouse Ventilation

The level of ventilation and airflow in your greenhouse affects the watering frequency. Proper ventilation promotes air circulation, which helps prevent excess humidity and reduces water loss through evaporation. Insufficient ventilation can lead to high humidity levels, increasing the risk of fungal diseases and the need for more frequent watering. Ensure your greenhouse has adequate ventilation to maintain optimal growing conditions.

Monitoring Soil Moisture

Watering by Sight

One of the simplest ways to monitor soil moisture is by observing the condition of the soil. The surface of the soil should not appear excessively dry or cracked, indicating a need for watering. However, relying solely on visual cues can be misleading since the top layer of soil may dry out faster than the deeper layers. It’s important to use other monitoring techniques in conjunction with visual observation.

Using a Moisture Meter

A moisture meter is an effective tool for accurately measuring the moisture content in the soil. Simply insert the probe into the soil at different depths to get readings. Moisture meters provide a quantitative measurement of the soil moisture levels, allowing you to determine when watering is necessary based on actual data rather than guesswork.

Considering Weight of Containers

The weight of the containers can also provide insights into the soil moisture levels. Lift the containers to determine their weight when the soil is moist and when it is dry. This will give you a baseline for assessing the moisture content in the soil. As the soil dries out, the containers will become lighter, indicating the need for watering.

Checking Soil Moisture Depth

To ensure that you are watering the plants adequately, it is important to monitor the moisture depth in the soil. Insert a finger or a probed tool, such as a skewer, into the soil to check how far down the moisture has penetrated. Ideally, the moisture should reach the root zone to ensure proper hydration. If the moisture is only concentrated in the top few inches of soil, additional watering is required.

Watering Techniques

Using Proper Watering Tools

Using the right watering tools is crucial for efficient and effective watering. Watering cans with narrow spouts allow for targeted watering directly at the plant’s base, minimizing water waste. Avoid using sprinklers or wide nozzles that can result in water spraying onto the foliage and increasing the risk of fungal diseases.

Watering at the Right Time of Day

Timing your watering is important to maximize water absorption and minimize water loss. It is best to water in the early morning or late evening when the temperatures are cooler and evaporation rates are lower. This allows the plants to take up water more effectively and reduces the chances of water evaporating before being absorbed.

Watering the Roots

When watering your plants, focus on watering the root zone rather than the foliage. Directing water at the roots ensures that the plants receive the maximum benefit and minimizes the risk of fungal diseases. Avoid overhead watering methods that wet the foliage excessively and can lead to leaf damage or diseases.

Avoiding Overwatering

Overwatering is a common mistake that can be detrimental to plant health. It can lead to root rot, oxygen deprivation, and nutrient leaching. To avoid overwatering, ensure that the soil has adequate drainage and allow the top layer of soil to dry out slightly between watering. It is better to slightly underwater than to overwater, as most plants can tolerate temporary drought conditions better than constantly saturated soil.

Maintaining Consistency

Maintaining a consistent watering schedule is important for the overall health and growth of your plants. Fluctuating watering patterns can stress plants and make them more susceptible to diseases and pest infestations. Establish a routine, considering the specific needs of your plants, and stick to it as closely as possible. Consistency in watering will help your plants thrive.

Water Requirements for Different Plants

Understanding Plant Watering Needs

Different plants have varying water requirements based on their natural habitat, growth habits, and root structures. Some plants, such as succulents and cacti, are adapted to survive in arid conditions and require infrequent watering. Others, like water-loving aquatic plants, need constant moisture. Research the specific watering needs of each plant species you are cultivating to provide them with the appropriate amount of water.

Drought-Tolerant Plants

Drought-tolerant plants, such as lavender, rosemary, and yucca, have adapted to survive in environments with limited water availability. These plants typically have deep root systems that can access water stored in the deeper soil layers. When cultivating drought-tolerant plants, it is important to allow the soil to dry out between watering to promote deep root growth and prevent waterlogging.

Water-Loving Plants

Water-loving plants, such as watercress, water lilies, and certain ferns, thrive in moist soil and require consistent watering. These plants typically have shallow root systems that do not reach deep into the soil for water absorption. Monitor the soil moisture closely for these plants, ensuring that the soil remains consistently moist without becoming waterlogged.

Vegetables and Fruits

Vegetables and fruits have varying water requirements depending on their stage of growth and the specific crop. Generally, maintaining consistent soil moisture for vegetables and fruits is important for successful growth and fruit production. Adequate watering during the germination and flowering stages is crucial for promoting healthy growth and bountiful harvests.

Herbs and Flowers

Herbs and flowers encompass a wide range of species, each with its own watering needs. Some herbs, like basil and parsley, prefer consistently moist soil, while others, like thyme and lavender, prefer drier conditions. Flowers also have varying water requirements based on their natural habitat. Research the specific watering needs of the herbs and flowers you are cultivating to provide them with optimal care.

Considerations for Hydroponics

Understanding Hydroponic Systems

Hydroponics is a soilless growing method that relies on a nutrient-rich water solution to provide plants with the necessary resources for growth. Watering frequency in hydroponics is different compared to traditional soil-based cultivation. Hydroponic systems typically recirculate the nutrient solution, enabling plants to access water and nutrients continuously.

Watering Frequency in Hydroponics

The watering frequency in hydroponics is determined by the plant’s growth stage and the specific hydroponic system being used. As the nutrient solution is constantly recirculated, plants have access to water and nutrients as needed. However, it is important to monitor the nutrient solution’s EC and pH levels regularly and make adjustments accordingly to ensure the plants’ optimal health.

Monitoring Nutrient Solutions

Monitoring the nutrient solution’s EC (electrical conductivity) and pH levels is crucial for hydroponic systems. EC indicates the nutrient concentration in the solution, while pH affects nutrient availability to plants. Regularly test and adjust the EC and pH levels to maintain a balanced nutrient solution for your plants.

Using Timers and Automation

Hydroponic systems often utilize timers and automation to control watering intervals and nutrient delivery. Timers can be set to provide plants with the appropriate amount of water and nutrients at specific times, ensuring consistent care. Automation systems can also help regulate environmental factors and optimize plant growth. Utilize timers and automation tools to streamline your hydroponic watering routine.

Coping with Environmental Factors

Hot and Dry Climates

In hot and dry climates, greenhouse plants are more susceptible to moisture loss due to high temperatures and low humidity levels. To cope with these challenges, increase the watering frequency and consider using shading or misting systems to cool down the greenhouse and raise humidity levels. Proper ventilation will also help dissipate excess heat and maintain a more favorable growing environment.

Cold and Humid Climates

In cold and humid climates, excess moisture in the greenhouse can lead to fungal diseases and plant stress. To cope with these conditions, ensure proper ventilation to promote air circulation and prevent excess humidity buildup. Water plants during the daytime to give foliage time to dry before nightfall, minimizing the risk of disease. Consider using heaters or insulation to maintain optimal temperatures for your plants.

Greenhouse Ventilation

Proper greenhouse ventilation is essential for maintaining optimal growing conditions and managing watering requirements. Ventilation systems promote airflow, control temperature and humidity, and prevent excessive moisture buildup. Ensure that your greenhouse has sufficient vents, doors, or fans to facilitate proper air exchange and regulate the growing environment effectively.

Managing Temperature and Humidity

Monitoring and managing temperature and humidity levels in your greenhouse is crucial for successful plant growth. Invest in a thermometer and hygrometer to regularly monitor these factors. Adjusting the greenhouse temperature and humidity levels through heating, shading, or misting systems can help maintain a conducive environment for your plants and support their watering needs.

Greenhouse Watering Schedule Examples

Seedling Stage

During the seedling stage, plants have delicate root systems that require consistent moisture for optimal growth. Water the seedlings gently with a fine mist or a watering can with a gentle showerhead. Aim to keep the soil consistently moist but not waterlogged. Water seedlings daily or as needed, ensuring that the soil does not dry out completely.

Established Plants

Once your plants have matured and established stronger root systems, the watering frequency can be reduced. Water established plants when the top inch of soil feels dry to the touch. Avoid overwatering, as this can lead to root rot and other diseases. Depending on the specific plant’s needs, established plants may require watering every 2-3 days or once a week.

Flowering and Fruiting Stage

During the flowering and fruiting stage, plants often have increased water demands to support fruit development. Monitor the soil moisture closely and adjust watering frequency as needed. It is important to provide consistent moisture to avoid fruit cracking or splitting. Water deeply to ensure the water reaches the root zone.

Winter Watering

In winter, when temperatures are cooler and evaporation rates are lower, plants generally require less frequent watering. Allow the top layer of soil to dry out slightly between watering to prevent waterlogged conditions. However, continue monitoring the soil moisture to ensure the plants receive adequate hydration.

Summer Watering

Summer often brings higher temperatures and increased evaporation rates, necessitating more frequent watering. Water in the early morning or late evening to minimize water loss through evaporation. Increase the watering frequency as needed to accommodate the plants’ increased water requirements. Monitor the soil moisture closely during hot and dry periods to prevent drought stress.

Using Mulch and Water Conservation Methods

Importance of Mulching

Mulching is a beneficial technique that conserves soil moisture by reducing evaporation rates and suppressing weed growth. Apply organic mulch, such as straw or wood chips, around the base of your plants. This helps maintain a more consistent soil moisture level and reduces the need for frequent watering.

Mulching Techniques

When applying mulch, ensure that the mulch layer is thick enough to suppress weeds and retain moisture. Apply a layer of mulch approximately 2-3 inches deep, making sure to leave space around the plant’s base to prevent rot. Mulch should be replenished as needed to maintain its effectiveness.

Drip Irrigation Systems

Drip irrigation is a highly efficient watering method that delivers water directly to the plant’s root zone. This method reduces water waste by minimizing evaporation and runoff. Install a drip irrigation system in your greenhouse to automate watering and ensure efficient water distribution. Drip irrigation systems can be adjusted based on the specific watering needs of your plants.

Rainwater Harvesting

Rainwater harvesting is an eco-friendly method of collecting and reusing rainwater for watering plants. Set up rain barrels or a rainwater collection system to capture rainwater from the greenhouse roof or surrounding areas. This method reduces reliance on municipal water sources and helps conserve water.

Water Recycling

Water recycling involves reusing water from various sources for irrigation purposes. Collect and store excess water from activities like washing produce or excess watering for reuse. This conserves water and reduces water wastage. Ensure that the recycled water is free from contaminants and suitable for your plants’ needs.

Common Watering Mistakes to Avoid


Overwatering is one of the most common mistakes gardeners make. It can lead to root rot, oxygen deprivation, and the leaching of nutrients from the soil. Avoid overwatering by allowing the top layer of soil to dry out slightly before watering again. Understand your plants’ specific watering needs and adjust accordingly to prevent overwatering.


Underwatering can also be detrimental to plant health. It can lead to stunted growth, nutrient deficiencies, and wilted foliage. Monitor the soil moisture levels closely and be attentive to signs of dehydration, such as wilting leaves. Adjust your watering schedule to ensure plants receive adequate hydration without drying out.

Watering the Foliage

Watering the foliage instead of the roots can promote the development of fungal diseases and can waste water. Aim to water directly at the plant’s base, allowing the water to reach the root zone where it is needed. This prevents excess moisture from accumulating on the foliage, reducing the risk of diseases.

Inconsistent Watering

Inconsistent watering can stress plants and make them more susceptible to diseases and pests. Establish a consistent watering schedule based on your plants’ needs and stick to it as closely as possible. Avoid significant fluctuations in watering frequency to promote stable growth and development.

Not Adjusting for Weather Conditions

Failing to adjust your watering routine based on weather conditions can lead to either underwatering or overwatering. In hot and dry weather, increase the watering frequency to compensate for increased evaporation rates. In cool and humid weather, reduce the watering frequency to prevent waterlogging. Stay alert to weather changes and adjust your watering schedule accordingly.

Troubleshooting Watering Issues

Wilting Plants

Wilting plants can be a sign of both overwatering and underwatering. Check the moisture levels in the soil to determine the cause. If the soil is overly wet, allow it to dry out before watering again. If the soil is dry, water the plants thoroughly and monitor their response. Adjust your watering routine accordingly to prevent wilting.

Fungus and Mold Growth

Excessive moisture on the foliage and in the soil can lead to the growth of fungi and molds. To prevent fungal diseases, avoid watering the foliage and ensure adequate ventilation in the greenhouse. If fungal growth occurs, treat the affected plants with appropriate fungicides and adjust the watering routine to minimize excess moisture.

Root Rot

Root rot is often caused by overwatering and poorly drained soil. To prevent root rot, ensure proper drainage in your pots or growing medium. Allow the top layer of soil to dry out between watering to moderate moisture levels. If root rot has already occurred, consider repotting the plant in fresh, well-draining soil and adjust the watering routine accordingly.

Nutrient Imbalances

Improper watering practices can lead to nutrient imbalances in the soil. Overwatering can cause nutrient leaching, while underwatering can result in nutrient deficiencies. Regularly monitor the nutrient levels in the soil and adjust your watering routine to ensure optimal nutrient availability to the plants.

Mineral Buildup

Watering with hard water or excessive fertilization can lead to mineral buildup in the soil. Mineral deposits on the soil surface indicate a need for flushing to remove the accumulated salts. Flushing can be done by thoroughly watering the plants to wash away the excess minerals. Adjust your watering and fertilization practices to minimize mineral buildup in the future.

In conclusion, watering frequency in a greenhouse is influenced by various factors such as the type of plants, stage of growth, size of containers, growing medium, temperature, and humidity levels. Monitoring soil moisture through visual observation, moisture meters, and checking soil moisture depth is essential for determining the watering needs of your plants. Using proper watering techniques, understanding the water requirements of different plants, and considering factors specific to hydroponic systems or environmental conditions are also crucial. Implementing mulching and water conservation methods, avoiding common watering mistakes, troubleshooting watering issues, and adjusting watering schedules accordingly contribute to successful greenhouse watering practices. By understanding these factors and implementing appropriate strategies, you can ensure that your greenhouse plants receive the right amount of water for their optimal growth and health.

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About the Author: Jake Scott