May Gardener's Calendar

May is characterised by warm spells and cool nights, fading bulbs and the herbaceous border growing in leaps and bounds. You still have the risk of a cold snap and heavy showers in May, remember the old English proverb, “Ne'er cast a clout till May is out!” But, May’s garden is bursting with life, colour and birdsong.

 

 

 

Sowing and planting 

Plant out summer bedding towards the end of the month once all risk of frost has passed. 

Take care in colder areas where it’s best to wait until June. Harden off plants raised from seed and cuttings. You can do this by leaving them outside for increasing periods of time.  It’s best to put them out at the warmest part of the day then build up to overnight exposure.  Do this for 10-14 days before planting them outdoors to ensure that their growth isn’t stunted. Also plant out summer-flowering bulbs such as Gladioli and Dahlias.  Dahlias grow best in full sun, but will tolerate partial shade.  Try to find a spot that provides at least six hours of sun a day.   If they are planted too early you run the risk of subjecting the tubers to freeze or rot. 

 

Tidying your garden – Cut back, prune and divide

If your Hostas are slow to come up and you haven’t done it already you can divide the plant before they come into leaf.

Now is the time to cut back old growth on trailing plants such as Aubretia to make the plants more prolific and encourage new blooms.   This month remove faded wall flowers and clear out spring bedding to make space for new summer bedding plants

Twining climbers, like Honeysuckle and Clematis, need to be tied in and around their supports. Also, support herbaceous plants, or heavy blooms like Peonies. before they are too tall

 

 

Prune spring flowering shrubs such as Berberis once they have flowered and evergreen shrubs such as Vibernum Tinus.  Trim evergreen shrubs that may have been damaged by frost.   Cut back tender shrubs such as Penstemon and hardy Fuchsias after danger of frosts have past.

 

May Garden Maintenance

Dead head any spring flowering bulbs so that the plant stores energy in the bulb rather than wasting it on seed production.  Allow daffodil and other spring bulbs foliage to die down naturally. Apply liquid fertiliser once bulbs have flowered.  Spring flowering bulbs need maintenance to ensure good flowering next year. 

Lift and divide overcrowded clumps of daffodils and other spring flowering bulbs. 

Pot on plants that are showing signs of being root bound.  Root bound plants will look ‘unhappy’, you might be able to see the roots growing out of the drainage holes, and it might wilt quickly after watering as there is no soil in the pot to retain the moisture.

Apply liquid feed to containers every 2 weeks and ensure tubs and baskets are well watered.  Use rainwater or recycled grey water where possible.

 

Protection

May can still produce a frost so make sure you protect tender plants. 

Pests such as Vine Weevil larvae can cause serious damage to containerised plants.   If you suspect Vine Weevil tip out the rootball and inspect for the creamy orange-headed maggots, which will tend to curl up into a ‘c’ shape. 

Try biological control for Vine Weevil safe for your vegetables too!

Other pests like aphids can multiply rapidly during mild spells.  Remove early infestations by hand to curb the problem.  Failing that try biological control products such as Ladybird Larvae – a natural predator of aphids. 

 

Vegetables

Potatoes grow very quickly under warm and moist conditions.  Now is the time to earth up Potatoes – this is drawing up the soil around the stems of the plants to leave a small shoot uncovered.  This increases the length of the underground stems that will bear Potatoes.  Plant any remaining tubers.

Mulch Strawberry plants to keep the fruits off the ground and deblossom Strawberry runners planted in the spring.  When the Strawberries start to swell, don’t water as much to avoid grey mould. Cover Strawberries and other fruit with netting to protect them from pests and birds.

Sow Beetroot, Winter Cabbages, Carrots, Peas, Broad and Runner Beans, Lettuce and Spring Onions.

Prepare your soil by removing weeds and raking the surface to break down large clumps of earth.  Make a furrow with a trowel then sow seeds finely.  Cover the seeds with soil and water well.  Stagger sowings to prevent a glut.


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