May is one of the most exciting months in the gardener’s year. Growth is well under way with seeds germinating and more needing to be sown, and young plants in the greenhouse and kitchen windowsill are aching to be planted out into the warm soil.
Ceanothus 'Autumnal Blue' shown here is an evergreen shrub bearing light blue flowerheads from late summer through to Autumn. Ideal for borders or for best results plant against a wall to protect it from the cold elements.
However, do take heed of the saying ‘Neer cast a clout till May is out’ because it could become true! Frosts can still occur and at this time of year and can do a lot of damage even to seemingly established plants. After all, we did have snow in some parts of the country only a week or so ago! Keep an eye on the weather forecasts and, on clear starlit nights, cover any tender plants and those which may have been forced into premature growth by last months warm spell. Cover with fleece overnight and remove after the sun has come up.
Nip off spent flower heads of Daffodils and Spring Bulbs and give them a sprinkling of Bonemeal fertiliser. This will stimulate growth and build up bulbs for next year. Leave the foliage on for at least another four to six weeks though, as this also helps to build up the bulbs and form the flower bud for next year’s display.
Now is the time to divide Primroses and Polyanthus as they finish flowering and replant them with a little compost to help them establish.
Don’t be tempted to plant out any half-hardy bedding plants such as Lobelia and Busy Lizzies until the end of the month Keep them in the greenhouse or another well lit position and slowly ‘harden them off’ by putting them outside during the day and bringing them back in at night.
Many plants will require support and nothing is better than birch or beech branches pushed in firmly and securely, using a little artistic skill in placing these unobtrusively. With hard ground it is sometimes difficult to push these twigs in deeply enough, but if a long metal rod is used to make the hole the task is then fairly easy. If you can’t get hold of suitable twigs, a vast range of plant supports are now available and now is the best time to get them in position before too much growth takes place.
Start to prune spring flowering shrubs such as Forsythia, Flowering Currant and Spiraea as soon as they finish flowering, removing old flowering wood and any week shoots. This allows new strong shoots to take their place, ripen and form flower buds for next year. Also trim winter-flowering Heathers with shears as soon as they go out of flower.
Plant up your garden pond this month or next with Water Lilies, Oxygenating Plants and Marginal Plants. Plant them in that order and fill your pool gradually. Overhaul previously established ponds early in the month by thinning growth and removing blanket weed.
Material courtesy of www.the-hta.org