Monthly Gardening Advice – May

Monthly Gardening Advice – May



  • Mow the lawn weekly and remember to add the clippings to your compost heap.
  • Continue to apply a high nitrogen liquid fertiliser to keep the lawn looking healthy.
  • Edge the lawn to create a ‘gutter’ around the lawn edge (this stops the lawn from growing into the border).
  • Ensure new lawns from seed or turf do not dry out.
  • If you have a problem with moss and weeds apply a combined moss and weed killer.

Houseplant Care

  • Increase the watering and begin liquid feeding.
  • Clean shiny leaved plants with a damp cloth and spiky plants with a soft brush.
  • Make sure houseplants get plenty of fresh air.
  • Move plants like citrus and cymbidiums outside on warm days and bring in if a chilly night is forecast.
  • Apply shade paint to the outside of the greenhouse glass or use blinds on sunny days to prevent temperatures soaring.

Jobs To Do In The Garden

  • Plant out summer bedding at the end of the month once frosts have cleared.
  • Hoe borders and beds to stop weed growth.
  • Divide cottage garden plants such as hosta and primrose.
  • Lift and divide overcrowded bulbs like daffodils.
  • Mulch around shrubs, roses and trees to help prevent moisture loss and suppress weeds.
  • Thin out outdoor sown hardy annuals.
  • Prune spring flowering shrubs once they have finished flowering (forsythia, spiraea, berberis and ribes)
  • Sweet peas can be trained onto their supports to create a good display.
  • Continue to plant container grown plants.
  • Dead-head pansies, violas and primulas.
  • Put supports in place for your cottage garden plants before they get too big.
  • Clip evergreen hedges if not too woody, shredded clippings can be added to compost heap (remember to check for nesting birds).
  • Tie in climbers.
  • Make sure tubs, hanging baskets and troughs are well watered. Use collected rainwater, or recycled grey water whenever possible.
  • Check for first signs of blackspot, aphid and rolling sawfly on roses and treat with a suitable pest and disease control.

Jobs To Do In The Greenhouse

  • Keep the temperature in the greenhouse at 5°C for fuchsia and geraniums and a warmer 12°C for topical plants.
  • Remember to ventilate greenhouse on sunny days and on the warmest days you may need to damp the floor down to increase the humidity.
  • Check seedlings for damping off, which can be a problem under glass (if it becomes a problem treat with ‘Cheshunt Compound).
  • Give plants more space as they grow to help avoid pest infestations.
  • Soft tip Fuchsia cuttings can be taken this month.
  • Greenhouse bulbs that have finished flowering can be given a high potash feed (Tomorite) to help build the bulb up for next season.
  • Warm up cold grow-bags before planting tomatoes, cucumbers and peppers by putting then in-situ.
  • Harden off half-hardy annuals, which have been started undercover and need acclimatise to the outside environment over a period of a week or so ready for planting in their final position.
  • Used shade paint on outside of greenhouse or blinds to stop temperatures soaring.

The Vegetable Garden

  • Earth up potatoes and promptly plant any still remaining.
  • Once the risk of frost has gone plant out tomatoes, courgettes and pumpkins, which have been grown undercover, they will need to acclimatise to the cooler outdoor environment.
  • Liquid feed plants regularly that grow in containers.
  • Net fruit and vegetable plants to keep birds off.
  • Sow melons in a heated propagator.
  • Protect brassicas from pigeons.
  • Put up codling moth traps.
  • Protect carrots with enviromesh to stop damage from carrot root fly
  • Make sure bees have access to flowers in cloches and cages for pollination.
  • Continue to prepare seedbeds and cover with fleece or polythene to warm the soil before planting.
  • Continue to harvest asparagus, spring onions, spring cabbage, radishes, salad leaves, spring cauliflower and leeks.
  • Protect flowers from possible late frosts.
  • Keep on top of weed control to help stop the spread of pest and disease.
  • Thin raspberry, gooseberries plants and de-blossom strawberry runners planted in spring.

Wildlife & Bird Care

  • Put up nesting boxes for migrant birds arriving in the UK.
  • Put up bat nesting boxes.
  • Keep birdbaths topped up with water.
  • Mow recently established perennial meadows but not annual cornfield meadows.
  • Put out log and/ or rock piles to create areas of shelter for wildlife
  • Avoid chunky foods that could choke young fledglings.
  • Hang a bee-nesting box.
  • Sow or plant a wildflower meadow.
  • Make sure you pond is more wildlife friendly (by planting around the pond and creating a shallow edge so wildlife can access the pond safely).
  • Leave informal hedges untrimmed for a while to provide food and shelter.

Any Other Advice

  • Collect grey water for watering containers and baskets.
  • If the weather warms up you may need to raise the cutting height on the lawn mower.
  • Remember to support your perennial plants to stop them flopping over later in the summer
  • In dry spell treat timber structures and buildings (remembering to use in a well ventilated space and use an appropriate product).

Enjoy your garden and don’t forget to take time and stop and stare at the wonder of nature. Happy gardening!