Here are your gardening jobs for the month – with added links if I have more information on the subject. They are all still relevant to do now if you’ve fallen behind or if the weather’s been bad.
If you’re seduced by ready-planted hanging baskets at the garden centre, make sure they’re properly hardened off – same with trays of annuals and veg.
Cover emerging shoots of potatoes with soil. If the tubers are exposed to light, they turn green because of an increase in chlorophyll, which makes them have a high level of glycoalkaloids toxins.
Mulching fruit crops will help them to retain moisture around the roots so you will use less water.
Take softwood cuttings of deciduous shrubs, including Forsythia, Fuchsia, Hydrangea macrophylla, Philadelphus and Spiraea – choose non-flowering stems.
Collect rainwater in barrels.
For roses, remove weeds and water during dry spells. Check roses for signs of black-spot, aphids and leaf-rolling sawfly damage, treat if required.
Trim winter-flowering heathers with shears.
After flowering, dig up and divide Primulas.
Tall-growing plants such as Delphinium, Lupin and monkshood need a framework of canes and string around then to help prevent them being damaged by winds. Do this now so the supports become unobtrusive as the plants grow through them.
Give shrubs, trees, and borders a mulch of compost, to preserve water and smother any weed seedlings.
Keep nipping off the dead flower heads of late-flowering daffodils and let the foliage die down naturally.
When old tulips have finished flowering, discard the bulbs, ready to plant up containers with summer bedding.
Harden off tender plants by leaving them outside for increasing periods of time, building up to overnight exposure for a fortnight, then plant in permanent places when the risk of frost has passed.
Thin out direct sowings of hardy annuals and vegetables, in two or three stages at fortnightly intervals.
Remove faded wallflowers and spring bedding, to make space for summer plantings.
Divide clumps of herbaceous perennials. Bamboos and clumps of bulbs or rhizomes can be divided in the same way.
Cutting back clumps of spring-flowering perennials such as Pulmonaria and Doronicum can encourage a fresh flush of foliage.
Lift and divide overcrowded clumps of daffodils after flowering. Deadhead tulips and daffodils. Apply a liquid fertiliser to bulbs after they have flowered, to encourage a good show next year. Allow foliage to die down naturally.
Inspect lilies for red lily beetles – they’re extremely destructive and active now.
Protect carrots with insect-proof mesh to prevent carrot root fly.
Liquid feed fruit trees growing in pots with a balanced feed every fortnight.
Sow cauliflower, purple sprouting broccoli, and winter bedding plants.
Spreading and trailing plants such as Alyssum and Aubrieta, can become tatty, so trim them back after flowering.
Put supports in place for herbaceous plants for those like peonies that produce heavy blooms.
Lift clumps of forget-me-not once the display wanes, and before too many seeds are released.
Pinch out leading shoots on plants such as Chrysanthemum and Helianthus to encourage bushy plants.
Pot on root-bound plants.
Tie in climbing and rambling roses as near to horizontal as possible, to restrict sap flow, causing more side-shoots to grow along the stem, producing more flowers.
Put netting in place to protect all soft fruit from birds.
Earth up potatoes when the shoots are 23cm (9in) high, in order to prevent the new tubers going green, leaving 5cm (2in) of shoot uncovered so that the plant has enough foliage to continue growing.
Hoe borders to prevent annual and perennial weeds from spreading and seeding themselves.
Sweet peas need training and tying into their supports to encourage them to climb and make a good display.
Liquid feed plants in containers every two to four weeks.
Aphids can multiply rapidly. Remove early infestations by hand to prevent the problem getting out of hand. Protect sweet pea plants in particular, as they can get sweet pea viruses.
Continue to protect lily, delphinium, hosta, and other susceptible plants from slugs and snails.
Prune spring-flowering shrubs such as Japanese quince (Chaenomeles), Choisya and Ribes after flowering. Remove one stem in three from Kerria and Spiraea ‘Arguta’, and shorten the other flowered stems to a suitable side shoot. Evergreens such as Viburnum tinus can also still be trimmed.
Prune wall-trained Pyracantha, removing any shoots coming out from the wall, and shortening other new growth to about 8cm (3in). This encourages spur formation and increases flowering.
Remove blanket weed in ponds by twirling around a rough stick. Skim off floating weeds such as duckweed with a net. Leave weeds on the pond side for 24 hours to allow trapped creatures to return to the water.