We’re in the height of spring and the beginning of summer is only a step away. May is a busy month and can be full of sowing, planting, splitting, weeding, watering and pest & disease prevention…
…enough to keep us all busy! Here is what we suggest you can get on with in May.

Watch out for late frosts!

Although the weather is getting warmer and staying more stable, we’re still not totally free from frosts and caution should be taken to limit any damage that may result. When frost is predicted, Tender growth, new plants and delicate plants can be covered with fleece or moved to protected areas when applicable (greenhouses, Cloches, windowsills etc.).

Keep lawns trimmed and tidy

The rate at which the grass grows will really be speeding up now, and so should your frequency of mowing. Regularly weeding and fertilising is a must to keep a healthy lawn. A high-nitrogen feed is recommended to boost growth, while the weed & moss killer will take away any competition. To save time (and potentially money) go for a combined product of feed & weed. Some products will also give extra benefits such as mycorrhizal fungal cultures which act as a root booster and will significantly boost grass production.


You can now prune any spring flowering shrubs that have finished flowering, as most of these will flower next year on this summer’s new growth. Prune your shrubs to maintain shape and vigour. Aim to trim back any dead wood, and prune away to open up the centre of the plant. On some mature specimens you can trim back severely (e.g. Kerria – down to a 1/3rd).

Some spring flowering shrubs to consider include;

  • Kerria, Chaenomeles, Choisya, Spirea, Deutzia, Weigela, Viburnum, Forsythia, Philodelphus... and many more

Check to make sure you don’t damage nesting birds.

It’s generally advised not to trim or prune hedges and trees between March and August as this is the main breeding season for nesting birds. It can be an offence to intentionally remove, or damage nesting bird material, although this usually in respects to hedgerows. If your unsure, we suggest leaving your pruning to before and after the nesting season, and to only prune if you absolutely sure you will do no damage. We all need to do our bit to help our native species!

Lift, split and replant your herbaceous perennials

You still have time to lift your clumps of perennials up and split them before any intense summer weather comes. Dig around the intended perennial and bring up the plant with as much of the rootball as possible. Hosta’s for example, tend to sulk and suffer when they lose roots. Examine the plant for where to split to ensure each part separated has enough roots and mass to survive.

As a general rule most clump forming perennials can be split around about now, Here are some of the more well known perennials you can split;

  • Primulas, Pulmonaria, Euphorbia, Helianthus, Zantedeschia, Iris, Crocosmia, and many more...

Don’t forget to feed me!

You can keep feeding spring bulbs a high potassium feed (tomorite) even after flowers have faded. Ideally you will want to keep feeding for up to 6 weeks after the flowers have faded and restrain from cutting back any dead leaves. We want to encourage the plants to store as much nutrients and energy as possible into their bulbs for next year, and part of this is letting the plant withdraw nutrients from the leaves.

Hanging baskets and containers don’t have the advantages that plants in the ground tend to have and so we must act to give them a boost. The biggest issue to overcome is the limited amount of soil to hold water and nutrients. We can tackle this by ensuring we use soil mixes and composts rich in organic matter/ moisture retaining materials (moss, moisture crystals). Depending on what we’re growing, we should also fertilise accordingly. If you want full displays of flowers or fruit then you should ideally feed a high potassium-based fertiliser (tomorite). Potassium will encourage flowers and in turn fruit. if you’re instead aiming for masses of green growth, a general balanced feed is better suited (growmore).

Pests & Diseases

Red lily beetle – The bane of lily and fritillary growers. Lily beetles will target foliage on lillies and fritillaries leading to a weakened plant which may not perform very well the following year. Mechanical removal is a viable option, but one should also remove eggs (orange/red sausage shaped) and grubs (reddish brown with black covering of excrement) to stand any chance. Pesticides are a more successful option, but caution should be taken to use pesticides when only needed as to not detriment beneficial insects.

Aphids – sap sucking pests that target a vast array of plants. Usual symptoms include twisted growth and a sticky residue. The sticky residue can cause fungal problems and can attract ants (who may farm the aphids for this residue!). luckily, we do have native predators, such as lacewings and lady birds. Encouraging these beneficial insects is always a good start. There are a lot of pesticides that can target aphids. Specialised pesticides for roses and fruit and veg are also available.

Blackspot on Roses – blackspot is a fungal problem that can really damage roses. The symptoms are very clear and easy to identify (black spots on the leaves). Treat as soon as you see any symptoms! This time of year you can spray your roses with a blackspot treatment as a preventative. Any fallen affected leaves should be removed from base of the plant.

Multi-functional pesticide that will target lilly beetles and aphids.
Another popular multi-functional pesticide that will target aphids and other pests. Also available in a vegetable and fruit safe verson
A specialised product to target blackspot on roses. Also has the extra function of targeting pests such as aphids.

Some of our other garden posts

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