Tips of the month – April / May

With the weather getting warmer and the risk of frost having passed, there is a lot that can be planted in both the flower and vegetable garden in April and May. 

Weather watch:

Although the risk of frost is diminishing, it is still a possibility as warm, cloudless days can be followed by cold nights. Keep an eye on the forecast and don’t be tempted to plant out tender plants until the first weeks in May.

Toughen up tender plants 

Seedlings nurtured indoors cannot be planted outside straight away. Instead toughen them up by placing them outside in a sheltered spot for a few hours during the day then bring them inside. Gradually increase the amount of time they spend outdoors . Do this for a period of one or two weeks before planting directly into the ground. 

Divide Primroses

These spring plants can become congested over time . To reinvigorate them  and keep them producing blooms in future years, divide after they finished flowering:

  1. Dig them up: choose a cool day when the ground is moist
  2. Separate the plants: Using a spade pull apart the clump or slice into sections.
  3. Replant your divisions: backfilling the planting hole with compost or leaf mould. 
  4. Water well. 

Prune spring-flowering shrubs 

Flowering shrubs such as forsythia, ornamental currants, viburnums, chaenomeles (flowering quince) need to be pruned straight after flowering towards the end of May, so there is plenty of time for new growth to develop and produce flowers next spring. 

  1. Use sharp, clean secateurs or loppers for thicker stems and remove any dead or damaged growth to a healthy bud or to the base of the stem.
  2. Prune out any stem growing in the wrong direction and spoiling the shape of the plant
  3. If the shrub is very congested, thin out the stems by removing a couple from the centre of the plant right down to the base. 

Plant out summer bedding and sweet peas 

Towards the end of May, plant out begonias, tender salvias, pelargoniums, lobelias, sweet peas… Acclimatise plants to outdoor conditions  by putting them outside during the day and bringing them in at night for a week or two. Put the necessary support in place for climbing and trailing. 

Plant up baskets and window boxes with tender plug plants 

For long lasting summer colours it’s the right time to plant up hanging baskets and pots. If it becomes too cold for these plants to stay outside, keep your baskets and containers in a porch or greenhouse for a couple of weeks. 

Sow beans 

  1. Sow dwarf, French and runner beans:  5 cm deep into deep pots of peat-free compost and germinate on a sunny windowsill. 
  2. Set up supports ready for climbing types:  simply place three to four bamboo canes into the ground and tie to gather at the top. 
  3. Plant the beans outside once they have established, from late May. 

Earth up potatoes

Once the stems are 20cm tall, draw soil up to form a ridge along the row. 

This protect shoots from frosty and excludes light, which turns potatoes green and inedible.

Grow salads

Ensure a continuous supply of fresh leaves by sowing a small amount of seed every two to three weeks. 

Plan for a winter harvest

Sow slower-growing vegetables such as cabbages, broccoli and kale for harvesting in winter. Sow seeds in module tray or seedbed for transplanting to final position later. 

Don’t forget 

  • Keep on top of weeds: regularly hoe off or pull out annual weeds to prevent them establishing  and setting seeds.
  • Get slug hunting: watch plants closely for signs of slug damage.
  • Train climbers: tie in soft new shoots of climbing clematis and honeysuckle to their support. 
  • Apply a mulch:  to retain moisture: late spring is the perfect time to apply mulch. Adding a 5-7cm layer will help to retain moisture before drier summer conditions arrive.
  • Set up plant supports: put plant support in place before perennials get too big.
  • Water wisely during dry spells: focus watering on newly planted specimens. Do your watering in the early morning or early evening to minimise water loss from evaporation. 

Bio-diversity at Great Dixter – a talk by Fergus Garrett

It was a privilege to welcome back to the April meeting of Aldersbrook Horticultural Society, Fergus Garrett, the Head Gardener at Great Dixter and Chief Executive of The Great Dixter Trust. Fergus is one of the most influential garden designers and horticultural educators in Britain today, he lectures internationally, is an adviser to RHS Wisley, and has received both the RHS Veitch Memorial Medal and the RHS Victoria Medal of Honour for outstanding contribution to the practice of horticulture. He began his talk by telling us about the House at Great Dixter, redesigned and enlarged by Lutyens for the parents of Christopher Lloyd. He spoke about Christopher Lloyd, at work in the garden at Great Dixter from childhood to his death aged 85; he developed the garden into an internationally known garden where new ideas were developed, becoming a hub of horticultural learning. He was the writer of 25 books and columnist for The Guardian and The Observer for many years. 

When Christopher Lloyd died in 2006, Fergus Garrett became Head Gardener and Chief Executive of the Trust that was established. In 2006 the gardeners at Great Dixter stopped using pesticides, used only organic fertiliser, bedded out fewer plants and watered less. Self sown, natural plants thrived like Cow Parsley and Foxgloves and the 3 acres of formal gardens looked more natural. The 35 acres of woodland were managed more effectively by cutting down trees and using the wood for hurdles etc, and in the grassland mosaic planting was introduced encouraging, in both areas, a wider variety of planting to encourage a greater range of wildlife. As a very old garden, Great Dixter has a rich seed bed and is deliberately planted with a long season of layered planting. The planting in the old walls and stone areas provide habitats, as do log piles and green roofs. After working with a number of wildlife groups starting with the British Arachnological Society which Fergus encouraged to come to the garden by offering them a venue for their annual conference once they were there they visited the garden, discovered 77 different species of spider in the compost bins and a species of spider that was last recorded in Sussex in the 1920s. Fergus got money form the Heritage Lottery Fund and commissioned a biodiversity audit led by Andy Phillips who discovered one of the richest sites for biodiversity he’s surveyed in 30 years and also discovered that the greatest range of biodiversity was actually in the 3 acre formal garden not in the surrounding meadows as they had expected. The results of their biodiversity audit is well documented and through their training programmes, the range of students who learn and work at Great Dixter and Fergus and his team’s energy and enthusiasm more and more gardeners are gardening naturally to encourage biodiversity in their own gardens. 

On the 14th June, members of Aldersbrook Horticultural Society will be visiting Great Dixter, and we have been invited to stay later, after the gates have closed, to enjoy the garden in all its glory.