Skip to main content

What to Do in the Garden This Week - May 21st

Published on May 21st 2020

by AlanGardenMaster. All rights reserved

purple allium flower bulbs
Now that the soil is warmer, you can get those cold-sensitive plants going. And it's not too late to plant a hanging basket or two or even more! With the whole summer ahead of us, now is the time to plant for colour!

Festival of Flowers:

Join us this month as we show some appreciation for all things plants, gardens and flowers. Gardens are our sanctuary, but in the last year especially, nature provided a place of comfort for us all. To join in the celebrations, follow us on social media and ShowUsYourBlooms, and you can keep up to date with the floral frivolities in the story below.
A close up of a flower

Candide's Festival of Flowers: What's On?


What to do in the garden this week

There's still time to plant up hanging baskets

  • It's still not too late to plant up a hanging basket! If you haven't done it before, then choose a basket with solid sides so that you only need to plant up the top.
  • When choosing plants for hanging baskets, aim for a central bushy upright plant - the "thriller". Then add 3 or 4 trailing plants - the "spillers".
  • Finally, plant some bushy growing plants to cover the area in between the thriller and spillers. These, of course, are called "fillers"!
A hanging basket full of flowers
  • Use the best potting compost available to get a fuller and longer display.
  • Add resin-coated, slow-release fertiliser tablets (Osmocote, Grow-Sure, etc.) so that your plants are well fed for most of the summer.
  • Water regularly and nip off any flowers that have gone over. This encourages more flowers to be produced.

Jobs for the greenhouse and poly-tunnels

  • Temperatures under cover can get very high so, besides plenty of ventilation, you'll need to put shade on the outside. You can provide shade by either using spray-on shade paint or provide netting to the roof of your greenhouse.
  • If your crops have suffered from red spider mite attacks in the past, damp the floor down regularly to raise air humidity. Don’t do it late in the day as this can encourage diseases. If you're going to use natural pest predators, introduce them as soon as you see the first pests.
Red spider mite damage on a cucumber leaf
  • Companion plants will encourage natural predators into your greenhouse and these will control pests. I find that pot marigolds or tagetes have worked very well for me. They work especially well on whitefly which can be extremely difficult to control in other ways.
  • Plant melons. They require hot and humid conditions, so they are great for polytunnels. They also like soil with lots of organic matter in it and masses of water!
A melon fruit

Borders and cut flowers

  • Trim foliage off early flowering perennials to encourage fresh new leaves. Lungwort (Pulmonaria) responds particularly well to trimming, and it will also get rid of the powdery mildew that they often get.
  • Tie up sweet peas regularly and remove unwanted side shoots. If you have the time, do remove the tendrils too.
  • Watch out for greenfly and check the small print carefully if you plan to use an insecticide, as some will harm your sweet peas.
  • Hostas can be divided this month. Lift clumps and split them, making certain that each shoot has plenty of roots attached.
Hosta Gold Standard plants
  • Watch out for scarlet lily beetles. This pest can eat your lily leaves in a few days! Pick them off and squash them.
  • However, the larvae are hard to see, and I use Provado Ultimate Bug Killer. A non-chemical alternative that will protect your plants is Grazers Beetle Control, but you'll need regular sprays.
Here are some alternatives to traditional pesticides:
Lily beetles


  • Sow sweetcorn directly into well-cultivated soil outside. Sow in blocks, not rows, for good pollination. F1 “Sundance” is a particularly good cropper and has been awarded RHS Award of Garden Merit.
Find "Sundance" and other corn varieties here.
  • Sow courgettes, pumpkins, squash, marrows and ridge cucumbers one seed to a pot. All like lots of organic matter so plant them with lots of compost. These can be grown on top of the compost heap.

Hope you enjoyed reading this weeks list of jobs in the garden! If you're looking for more inspiration on what to plant, check out our May Growing Guide!

Related articles

In the garden


10 of the Best Garden Plants for Bees

One of the best ways we as gardeners can help is to increase the range of nectar-producing plants we grow in our gardens.
A close up of a flower

Slow reads


Learn to Identify the 10 Most Common Types of Bee in the Garden and How You Can Help Feed Them

World Bee Day 2021 falls right in the middle of Candide's Festival of Flowers, which is a perfect opportunity to celebrate one...
A close up of a flower

Slow reads


Bumblebees Awaken

As the weather warms up, some of the first bees to visit our gardens are the large and familiar bumblebees.