Here in Birmingham, the weather has been as changeable as ever, very warm just before Easter followed by a cold spell only last week. During May the threat of further frost will largely pass and, with spring well under way, Robert Hall is in no doubt that this is going to be a busy month in the garden.
Hanging Baskets will be arriving in our Garden Centre during early May, perfect if you want fabulous colour decorating your garden throughout the summer.
If you are making up your own basket don't forget to include water retaining crystals and slow release fertilizer. Baskets need to be watered daily, perhaps twice in hot weather, and dead heading will ensure the colour keeps on coming.
Plant out sweet peas in a moisture retentive soil containing lots of organic matter, water in well. Tie to support sticks for the first four to six weeks then they will become self-supporting.
Continue to sow successive rows of vegetables. Keep hoeing, hand picking and digging up weeds before they set seed, making sure the roots of perennials are completely removed. If it's too cold for some crops such as French beans, pumpkins and squash, sow them inside to plant out when the weather is warmer.
If you need space that has been taken up by bulbs that have finished flowering, lift them without damaging the foliage and place them in a shallow trench. Cover the bulbs with earth and wait until the foliage has died down before lifting, cleaning and storing. Remove seed heads from daffodils and tulips but not the foliage.
Sort out any herbs that have become woody over winter by cutting back to encourage new growth.
Begin to lower the blades on the lawn mower. This will keep the lawn neat and slice through annual weeds. If you want a pristine lawn, a regular regime of feeding and weed control should be adopted.
Remove by hand any suckers from shrubs and fruit trees to just below ground level and use a thick mulch to discourage them.
Actively encourage birds into the garden with food and a regularly replenished bird bath but avoid trimming hedges as you may damage the habitat of nesting birds.
Start hardening off summer bedding and all your half-hardy plants in a cold frame or by placing them outside for an increasing amount of time during the day.
Lift and divide primroses after flowering.
Net strawberries to discourage birds now and remove blossom from first year plants. Ensure that other fruit is well watered and thin out gooseberries to encourage larger fruit. Remove excess raspberry canes before they become too congested that will encourage disease.
Prune spring-flowering shrubs such as viburnums, lilacs and forsythias once their blooms have faded, to ensure their shape is maintained, new strong growth is encouraged and weak, old and unproductive stems are cut out.
Earth up potatoes when new shoots show through. This protects them from a late frost and also direct sunlight that will turn the tubers green. If there's a dry spell they will appreciate some water. Support broad beans with twine.
It’s already time to start thinking about Halloween and a job that might interest children is to sow pumpkin seeds on their side in a 3in pot about 1in deep and cover with cling film to help retain moisture and warmth. Place on a windowsill, pot on and finally plant out in a sunny fertile spot.
To avoid carrot fly, sow later in the season, choose a resistant carrot variety or try companion planting with onions or garlic and sowing amongst other vegetables, covering with fleece or surrounding the plot with 2ft high barrier of polythene or similar material.
Thin out spinach, lettuce and any other seedlings that have been directly sown in the vegetable bed. Pea plants will need supporting with twiggy branches.
During dry periods, remember to keep young trees well watered.
Plant out cabbages and to protect these and other brassicas from cabbage white butterflies from laying eggs, cover with netting. Deter cabbage root fly by fitting brassica collars that can be made with roofing felt or carpet underlay.
You might not be familiar with the 'Chelsea Chop' but it’s useful if you want to extend the flowering period of herbaceous perennials. Asters, campanulas, heleniums, phlox are amongst those that can benefit, delaying flowering and leading to stockier growth and perhaps smaller but an increased number of blooms. Cut back the stems by two thirds in the last week of May or only a proportion for a long succession of flowering.
Greenhouse tomatoes will now need plenty of water, perhaps twice a day but less for cherry tomatoes. Spray them with water to encourage pollination and use a liquid tomato fertilizer as directed. Don't forget to pinch out side shoots.
If you are also growing a greenhouse grapevine, allow only three leaves to develop after a fruiting truss before pinching out the tip.
Plant runner beans in the trench that you've filled with organic matter over the past few weeks. Put in place a double row of bamboo canes, 9ins apart with a 2ft gap between the rows.
Alternatively grow up a wigwam of four or six poles tied together. Plant two seeds at the base of each cane at a depth of 2ins.
Support broad beans with canes and string around the perimeter of the plot.
May Pond Maintenance
May is a good time to introduce new life into your pond, give it a spring clean and prepare for the summer.
Netting should have prevented autumn leaves from falling into your pond but if any debris or decaying plant matter has collected, it should now be removed with a net or a pond vacuum.
If you have a UV filter pump, the bulb needs to be changed each year as its effectiveness deteriorates over time. Left unchanged it will become ineffective at eradicating suspended algae (green water). All types of pond pump should also be cleaned out to maintain optimum performance.
As water temperature slowly increases fish will become more active. Feeding can be increased and the type of food changed from wheatgerm based products to more proteinous fish food.
This is an excellent time to introduce new plants into the pond using specialist planting and aquatic compost, this allows them to become established before the summer.
Sunlight increases the growth of algae in the pond so floating plants such as water hyacinth can be beneficial as they shade the water, think about deep water plants such as lilies or marginal primulas and marigolds to achieve a varied aquatic landscape.
Although you must be careful not to overstock your pond, add fresh fish by initially floating the bag in which they arrive in your pond for about half an hour. This will equalise the temperature and reduce the chances of the fish feeling any shock from a sudden change of temperature. Don't add too many at once and keep an eye on the fish as they adjust to a new environment.
Bear in mind that timings for various gardening and aquatic activities vary throughout the country, these are jobs we expect to undertake in the Midlands, but there are no hard and fast rules for everyone.