May Greenhouse Gardening
As spring reaches its peak, May presents the perfect opportunity to prepare your garden and greenhouse for a vibrant summer. With longer days and warmer temperatures (especially with how lucky we’ve been this year, in 2025), plants are in active growth, making it an ideal time to sow, plant, and nurture.
Greenhouse Care
May is a transitional month for greenhouse plants.
Acclimatise Tender Plants: Begin moving plants like Cymbidium, Ficus, and Citrus outdoors during warm days. However, be prepared to bring them back inside if cold nights are forecast.
Clean Plants: Dust can hinder photosynthesis. Wipe shiny-leaved plants such as Anthurium with a damp cloth, and use a soft brush for spiky varieties.
Repotting: Check for root-bound plants. If roots are circling the pot, it’s time to repot using fresh, peat-free compost.
Flower Garden Tasks
May is the month to ensure your flower beds are bursting with colour.
Prune Spring-Flowering Shrubs: After flowering, prune shrubs to maintain shape and encourage healthy growth.
Plant Summer Bulbs: Once the risk of frost has passed, plant out Dahlia tubers and Cannas for a summer display.
Support Climbers: Tie in new shoots of climbing plants such as Clematis, Wisteria, and Honeysuckle to their supports to guide growth.
Sow Annuals: Continue sowing hardy annuals directly into borders for late summer colour.
Prepare Hanging Baskets: Plant up hanging baskets but keep them in a greenhouse or sheltered spot for a few weeks to establish before placing them outside.
Vegetable & Allotment Jobs
Maximise your vegetable harvest with these timely tasks:
Sow Tender Vegetables: Sow seeds of Runner Beans, Courgettes, and Pumpkins under cover. These can be planted out once all danger of frost has passed.
Harvest Early Crops: Begin harvesting early crops like Lettuces and Radishes. Regular picking encourages further production.
Support Climbing Vegetables: Install supports for climbing vegetables such as Peas, Mangetout and Beans to promote healthy growth and ease of harvesting.
Fruit Garden Focus
Ensure a bountiful fruit harvest with these care tips:
Water Young Fruit Trees: Young trees are establishing their root systems and require consistent watering during dry spells.
Remove Early Fruits: On newly planted fruit trees, remove any blossoms or developing fruits to allow the tree to focus energy on root and branch development.
Protect Soft Fruits: Place netting around soft fruit plants like Gooseberries and Strawberries to prevent birds from stealing your crop.
Monitor for Pests: Regularly inspect Gooseberry bushes for Gooseberry Sawfly caterpillars, which can quickly defoliate plants.
Wildlife & Garden Maintenance
Promote biodiversity and maintain garden health:
Attract Pollinators: Plant nectar-rich flowers to attract bees and butterflies, essential for pollination. Keep dandelions to feed the bees until other plants in the garden are flowering. Do not use pesticides that are dangerous to bees, it will say on the back of the bottle whether they are Bee Safe.
Hedgehogs: Hedgehogs have recently been placed on the ‘Endangered’ list. Ensure you put down shallow bowls of water for them to drink (do not feed Milk), and some food. See the RSPCA information on Hedgehog care here: Hedgehogs In Your Garden | RSPCA – RSPCA – rspca.org.uk
Feed Spring Bulbs: Apply a liquid feed to spring-flowering bulbs like Tulips and Daffodils to replenish energy stores for next year.
- Maintain Lawns: Regular mowing and edging keep lawns tidy. Consider leaving a patch uncut to support wildlife. We kept a plot a little bit wild under the pear tree this year – and I’m certain it’s the reason the pear tree has the most pears we’ve ever had on it, as the dandelions underneath were attracting the bees.
Greenhouse Growing in May
May is an active month for greenhouse gardening:
Ventilation: As temperatures rise, ensure your greenhouse is well-ventilated to prevent overheating. We sell a range of automatic roof vent and louvre openers Ventilation Archives – The Greenhouse Shop
Shade Management: Install shading or blinds to protect plants from intense sunlight – Heat & Shade Archives – The Greenhouse Shop
Pest Control: Monitor for pests like aphids and whiteflies. Introduce biological controls or use appropriate treatments as needed.
Regular Feeding: Feed greenhouse plants with a balanced fertiliser to support vigorous growth.
Final Thoughts
We’ve had such a strong start to the Spring season of 2025, with lovely warm Spring weather. The light evenings mean we have longer to potter in the greenhouse after a long day at work, sowing seeds, re-potting established plants like tomatoes and cucumbers into their final growing space/containers.
One thing that has stood out this spring is the lack of rainfall. While the sunshine has been welcome, our water butts may be running a little low. If your greenhouse isn’t yet equipped with a rainwater collection system, this is a great time to consider installing one. Not only is harvested rainwater better for your plants than treated tap water, it’s also more sustainable and cost-effective. You can find a range of greenhouse rainwater collection solutions on our website under the ‘Rainwater Collection’ section.
And speaking of rain – or rather the lack of it – now’s the time to give your greenhouse a good clean. Without regular rainfall, dust and grime can quickly build up on glass panes, reducing light levels and airflow. A quick rinse-down with clean water can make a huge difference to plant health and growth.
As temperatures continue to climb, greenhouse shading becomes essential to prevent plants from overheating. Prolonged exposure to intense sunlight can stress seedlings, wilt foliage, and even scorch tender crops. Shading is also important to think about, as the season progresses through to Summer, we offer internal shading options such as blinds and netting, which are easy to install and allow you to adjust coverage as the season progresses. These are available on our website under ‘Heat and Shade’.
