Greenhouse Gardening Glory: Your Ultimate Calendar from March to December

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March: Awakening the Greenhouse
April: The Growth Spurt Begins
May: Transition and Hardening Off
June: Full Swing Gardening
July: Midsummer Maintenance
August: Peak Harvest Time
September: Preparing for the Cool Off
October: Autumn Adjustments
November: Winding Down
December: Planning and Reflection

As an avid greenhouse gardener myself, I’ve experienced the highs and lows of managing a thriving garden under glass. From the first sprouts of March to the final harvests of November, each month brings its unique challenges and rewards. This has been an ongoing concern for gardeners throughout history. I’m here to share my personal calendar and tips for greenhouse gardening glory, so grab your gardening gloves, and let’s dive in!

March: Awakening the Greenhouse

Starting Seeds Indoors

March is all about beginnings. It’s time to start your seeds indoors to get a jump on the growing season. Use a quality seed starting mix and keep those little guys warm and moist. Trust me, watching those first green shoots emerge is nothing short of magical.

Preparing the Soil and Pots

Get your soil ready for its plant inhabitants. Mix in some compost to give your plants a nutrient-rich environment. Also, ensure your pots and trays are clean to prevent any disease from last season from affecting your new plants.

April: The Growth Spurt Begins

Transplanting Seedlings

By April, your seedlings will be ready to move into larger pots. Be gentle during the transplanting process to avoid shock, and give them plenty of room to grow.

Managing Greenhouse Humidity and Temperature

April can still be a bit unpredictable weather-wise. Monitor the humidity and temperature in your greenhouse closely. Ventilation is key to preventing mold and mildew.

May: Transition and Hardening Off

Introducing Plants to Greenhouse Conditions

As the weather warms, it’s time to prepare your plants for the great outdoors. Start by placing them outside for a few hours each day, gradually increasing their exposure to the elements. This process, known as hardening off, is crucial for their survival.

Pest Control Strategies

Pests start to become more active in May. Keep an eye out for unwanted guests and employ organic pest control strategies as needed. Prevention is always better than cure.

June: Full Swing Gardening

Pollination Tips

Many greenhouse plants need help with pollination. You can gently shake flowering plants to mimic the effect of the wind or use a small brush to transfer pollen from flower to flower.

Fertilization Techniques

Regular fertilization is crucial for healthy, productive plants. Use a balanced, water-soluble fertilizer and follow the recommended rates to avoid over-fertilization.

July: Midsummer Maintenance

Pruning for Health and Yield

Pruning is not just about keeping your plants looking tidy. It’s about directing energy to the most productive parts of the plant. Remove any dead or diseased foliage and consider pruning to encourage branching.

Watering Wisdom

Watering needs increase as temperatures rise. Water deeply and less frequently to encourage strong root growth. Early morning is the best time to water to reduce evaporation and disease risk.

August: Peak Harvest Time

Harvesting Tips

August is often the most rewarding month. Harvest your crops regularly to encourage continued production. Don’t forget to enjoy the fruits (and vegetables) of your labor!

Continuous Crop Care

Even as you harvest, continue to monitor for pests, diseases, and nutritional needs. Your plants still need your attention to produce well into the fall.

September: Preparing for the Cool Off

Greenhouse Planting for Fall

September is the time to plant cool-season crops if your greenhouse is heated. Think about greens like spinach and kale, which can thrive in the cooler months.

Temperature Management

As the nights start to cool, begin to pay more attention to your greenhouse’s temperature. A small heater might be necessary to keep those temps steady.

October: Autumn Adjustments

Extending the Greenhouse Growing Season

With a greenhouse, your growing season extends far beyond that of outdoor gardens. October is a testament to this, as you can still enjoy fresh produce long after your outdoor gardening friends have packed up.

Preparing Perennials for Winter

If you have perennials in your greenhouse, now is the time to prepare them for winter. Mulching and reducing watering can help them enter dormancy properly.

November: Winding Down

Final Harvests

November might bring the final harvests of the year, but what a journey it has been. Collect seeds from your favorite plants for next year and begin the process of clearing out spent plants.

Greenhouse Cleanup and Maintenance

A clean greenhouse is a happy greenhouse. Take the time to remove any plant debris, sanitize surfaces, and prepare your space for the next growing season.

December: Planning and Reflection

Reviewing the Year

December is a month for reflection. Look back on your successes and challenges. What worked? What didn’t? Use this information to plan for an even more successful year ahead.

Planning for Next Year

Start dreaming about next year’s garden. Order seed catalogs, sketch out your plans, and maybe even consider new plants or techniques you want to try. The possibilities are endless.


Greenhouse gardening from March to December is a journey of growth, challenges, and immense rewards. By following this calendar, you’re well on your way to experiencing the glory of greenhouse gardening for yourself. Remember, every gardener’s journey is unique, so adapt these tips to suit your situation and enjoy the process.


What’s the best way to start seeds indoors?

The best way to start seeds indoors is by using a sterile, nutrient-rich seed starting mix and shallow trays or pots that ensure good drainage. Make sure to place your seeds at the proper depth according to their size; smaller seeds should be sown on the surface, while larger ones can be buried a bit deeper. Provide consistent warmth (a heat mat can be very helpful) and light (either natural light by a sunny window or artificial grow lights) to encourage germination. Keep the soil moist but not waterlogged, and once seedlings emerge, ensure they receive enough light to prevent them from becoming leggy. As they grow, thin out the seedlings to prevent overcrowding and transplant them into larger pots if necessary before moving them to the greenhouse or outdoors.

How can I naturally control pests in my greenhouse?

Natural pest control in a greenhouse can be achieved through several methods. First, introduce beneficial insects such as ladybugs or lacewings that prey on harmful pests. Use physical barriers like insect netting to prevent pests from entering. Practice good hygiene by removing plant debris and weeds that can harbor pests. Employ crop rotation and companion planting to deter pests naturally. Neem oil, diatomaceous earth, and insecticidal soaps can be used as organic treatments for infestations. Monitoring plants regularly for early signs of pests will help you take timely action and prevent widespread infestations.

What are some tips for successful plant pollination in a greenhouse?

To ensure successful plant pollination in a greenhouse, you can manually pollinate plants by using a small brush or cotton swab to transfer pollen from one flower to another. This is especially useful for plants that are not wind-pollinated or do not have natural pollinators in the greenhouse. Installing a small fan can help mimic natural wind and aid in the pollination of certain plants. Introducing pollinators such as bees can be beneficial if your greenhouse environment supports their needs. Also, selecting self-pollinating varieties or plants that do not require pollination to produce fruit can simplify greenhouse gardening.

How can I extend my growing season into the colder months?

Extending your growing season into the colder months can be done by using a greenhouse, cold frames, or row covers to protect plants from frost. In a greenhouse, consider installing a heating system to maintain optimal temperatures during very cold weather. Additionally, choose cold-tolerant plant varieties that can thrive in lower temperatures. Utilizing thermal mass, such as water barrels or stone, can help store heat during the day and release it at night, keeping the greenhouse warmer. Layering horticultural fleece over plants on particularly cold nights can also provide extra protection.

How should I prepare my greenhouse for winter?

Preparing your greenhouse for winter involves several key steps. Clean the greenhouse thoroughly to remove any plant debris, pests, and diseases. Check and repair any structural damages to ensure it’s sealed and insulated against cold drafts. Install thermal screens or bubble wrap on the inside of the glass to improve insulation. Consider a heating system to maintain a minimum temperature during extreme cold. Water plants less frequently, as they require less water during the shorter days of winter. Finally, monitor the greenhouse temperature and humidity levels closely throughout the winter to adjust heating and ventilation as needed.

Embarking on your greenhouse gardening adventure with this calendar in hand, you’re set to enjoy a year filled with growth, learning, and, of course, a bountiful harvest. Here’s to your greenhouse gardening glory!

Woman with a large hat standing inside a greenhouse with back facing camera.


Hey there, I'm Elise, the passionate blog writer behind As a dedicated gardener and nature enthusiast, I'm thrilled to share my knowledge and love for greenhouse gardening, indoor gardening, and eco/sustainable practices with you. Let's embark on this gardening journey together and discover the joy and fulfillment of nurturing nature right in our own homes.

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