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As the Irish summer unfolds, your greenhouse becomes more than just a shelter from spring chill—it's now a thriving hub for heat-loving crops, a space to relax, and a head start on your next harvest. June is a pivotal month for gardeners: full of opportunity to both enjoy the early fruits of your labour and prepare for the seasons ahead. 

Here’s your complete guide to making the most of your greenhouse this June—from sowing summer favourites to preparing autumn and winter crops, plus essential care tips to keep everything growing strong. 

Heat-Loving Crops to Sow in June

Even if you’ve already planted your main summer crops, June is a great time to squeeze in one more sowing round for a longer harvest season. 

Tomatoes

Still time to sow a few varieties for late summer or early autumn cropping. 

  • Support with bamboo canes or plant spirals, all stocked at Lenehans. 

  • Watch for yellowing leaves—a sign they may need tomato feed. 

  • Manually pollinate flowers with a soft brush if bees can’t get in. 

Sweet Peppers & Chillies 

  • Use sticky traps to monitor whitefly and aphid activity. 

 Cucumbers

  • Ensure consistent watering to avoid bitter fruit. 

Basil, Coriander, Parsley & Tender Herbs 

  • Basil is not only delicious—it also repels aphids and makes a great companion to tomatoes. 

  • Herbs love the stable warmth of the greenhouse but are quick to suffer from under-watering. 

  • Ensure consistent moisture and good airflow to prevent mildew. 

Autumn & Winter Crops to Sow in June 

Don’t pack the seed trays away yet! Many cool-season crops should be sown now for late-year harvests. 

Leeks 

  • Sow late-cropping varieties now for harvests from late autumn through early spring. 

Kale 

  • Start sowing Kale now for harvests through the colder months.

  •  Needs good airflow—consider installing louvre vents for ventilation. 

Broccoli 

  • Sow broccoli seeds now for late-year harvesting. 

  • Choose varieties suited to autumn cropping. 

  • Keep plants well-watered and protected from cabbage white butterflies. 

Cabbage 

  • Ideal month for sowing winter cabbages. 

  • Pick hardy, late-season varieties and transplant into beds in midsummer. 

Brussels Sprouts 

  • June sowing will deliver sprouts just in time for festive meals. 

  • Keep an eye on aphids and give them plenty of space to grow tall and strong. 

Essential June Greenhouse Care Tips 

Irish weather may be unpredictable, but inside your greenhouse you can create a controlled environment for success—if you stay ahead of seasonal challenges. 

Ventilation 

  • Open roof vents and doors daily, especially on warmer days. 

Shade 

  • Even in Ireland, direct sun can stress plants. 

  • Apply shade paint, use shade netting, or hang Tarpaulin to reduce light intensity. 

  • Ensure shading doesn’t block too much light—balance is key. 

Watering 

  • Water in the early morning or late evening to avoid rapid evaporation. 

  • Keep the soil moist, not soggy—especially for fruiting crops.

  • Use watering cans or drip irrigation and avoid splashing leaves to reduce fungal risks. 

Pollination 

  • Greenhouses limit natural pollinator access. 

  • For crops like tomatoes, peppers, and melons, use manual pollination techniques—shaking plants gently or using a small brush on the flowers. 

Pest Control 

  • Inspect for aphids, whiteflies, spider mites. 

  • Remove damaged leaves to prevent spread. 

What else to do in your Greenhouse in June 

  • Clear out spring crops like spinach or salad leaves that are bolting. 

  • Repot or move mature plants like citrus or overwintered geraniums outside to make space. 

  • Use the newly freed-up area for trays of seedlings or for summer seating if you want to relax among the greenery. 

In Summary: Your June Greenhouse Checklist 

  • Improve ventilation and install shade solutions 

  • Water wisely and monitor for pests 

  • Manually pollinate crops if insects can’t reach them 

  • Plan space for succession planting or even summer relaxation 

From ventilation kits to shade netting, growbags, hand tools, watering cans, and pest solutions, Lenehans.ie has everything you need to keep your garden and greenhouse thriving in any Irish summer. 

Shop online or drop into our store to find trusted brands, expert advice, and unbeatable value, so you can focus on what really matters: growing strong, healthy plants all year round.