March Greenhouse Gardening: Your Complete Guide
March is a favourite time of year! As spring lambs make their first appearances and the evenings grow lighter, your greenhouse transforms into a hub of growth and possibility. With longer days and rising temperatures, it’s the perfect time to nurture delicate seedlings and established plants – setting the stage for a ‘fruitful’ growing season ahead. (See what we did there? )
Preparing Your Greenhouse
With spring just around the corner, March is the ideal time to plan ahead and get growing! This month calls for a mix of greenhouse maintenance and strategic planting to set the stage for a successful season.
Greenhouse Maintenance and Cleaning
Although you have likely performed a thorough clean in February, March requires continued vigilance:
- Conduct a follow-up inspection of your greenhouse structure
- Check seals and repair any draft points
- Ensure ventilation systems are fully operational
- Remove any remaining winter debris
Climate Control
March weather can be unpredictable, with sudden temperature shifts. Your greenhouse management must be equally adaptive:
- Use automatic vent openers to regulate temperature
- Keep temperature-sensitive plants protected
- Monitor humidity levels, especially as plant growth accelerates
- Use digital thermometers to track daytime and nighttime temperature variations
Water Management
As plant growth intensifies, water management becomes crucial:
- Begin increasing watering frequency
- Check irrigation systems for winter damage
- Ensure water butts and collection systems are clean and functional
- Use lukewarm water to avoid shocking plant roots
- Consider installing a drip irrigation system for consistent moisture
Pruning and Plant Care
March is an ideal month for strategic pruning and plant preparation:
- Remove any remaining dead winter growth
- Prune overwintered plants to encourage robust spring growth
- Inspect plants for early signs of pest activity
- Gently remove any yellowing or damaged foliage
What to Plant in March
Vegetables
March offers tremendous opportunities for vegetable cultivation:
- Tomatoes: Start seeds indoors in heated propagators
- Use modular trays for easy transplanting
- Maintain consistent temperatures around 20-25°C
- Provide bright, indirect light
- Peppers and Chillies: Begin seed germination
- Require warm conditions (around 22-25°C)
- Use heated propagators
- Sow in small, individual modules
- Salad Crops:
- Lettuce
- Rocket
- Spinach
- Radishes
- Quick-growing and tolerant of cooler temperatures
- Root Vegetables:
- Early carrots
- Beetroot
- Turnips
- Use deep containers to allow proper root development
Flowers
March is an exciting month for flower enthusiasts:
- Annuals to Start:
- Marigolds
- Zinnias
- Sunflowers
- Nasturtiums
- Calendula
- Perennials:
- Delphinium
- Lupins
- Foxgloves
- Start in seed trays, maintaining consistent moisture
Herbs
Establish your herb garden with:
- Basil
- Parsley
- Coriander
- Chives
- Mint
Expert Tips for March Success
- Use seed heat mats to improve germination rates
- Invest in quality seed-starting compost
- Label all plantings with variety and date (learnt my lesson with that last year, when I assured myself ‘I’ll remember’. Spoiler alert – I didn’t).
- Rotate seed trays to ensure even light exposure
- Use fine mesh to protect emerging seedlings from pests. I find netted curtains work well.
Additional Considerations
- Gradually harden off plants started indoors
- Prepare outdoor beds by adding organic matter
- Monitor weather forecasts for unexpected frost
- Keep horticultural fleece accessible for cold nights
Final Thoughts
March in the greenhouse is a month of promise and potential. By providing careful attention, maintaining optimal growing conditions, and selecting the right plants, you’ll create a thriving ecosystem that bridges winter’s dormancy and spring’s vibrant renewal.
Remember, successful greenhouse gardening is part science, part art, and entirely about patience, observation and the love of greenhouse gardening.
