Azalea May

Garden Shed: May

Time now to enjoy your garden. In May, keep an eye out for unwelcome late frosts, have your hoe handy and be ready to take actions against pests. On hot dates, ventilate your greenhouse.


Mow lawns regularly, trim the edges to neaten them up. Apply spring weed and feed if not already done. By applying topdressing, you can improve uneven lawns.


Plant Gladioli, Begonias, Lilies and Cannas now but it is wise to start them off in small fibre or peat pots until they have a good root system on them before they go in to the soil outside. The soil is still a bit too cold and wet for direct planting of many things so although it can be a bit tedious, it will save disappointment later. Stagger the planting of the Gladioli to extend the flowering period. Place stakes or canes in the soil before you plant.

Sweet peas started earlier in the year will be ready to set out. Construct some sort of support, a wigwam made of bamboo canes works well. Pinch out the tips when they are 6” tall ensuring they break and produce more shoots. To extend the flowering, make a second sowing in trays and plant out into the open ground in the next couple of weeks. Remember to soak the seeds overnight, this will speed up the germination.

Lift and divide overcrowded beds of spring bulbs.

Trees and Shrubs

Cut back Clematis Montana after it has flowered. Under normal circumstances, you would enjoy the flowering, and then cut it back as hard as necessary. It is easier to determine what is alive and what is dead when there is new growth. Montana is the most widely known early flowering clematis, but there are now more of the alpine clematis sold in garden centres, which are even earlier.

Hedges may be ready for their first trim, check for wildlife before you start.


Gooseberry bushes are prone to mildew and gooseberry sawfly caterpillars will strip the young leaves leaving only the midrib of the leaf. Eggs are laid on the underside of the leaf usually. Benomyl will tackle the mildew, while pyrethrum, permathrin fenetrothion will help to control the sawfly.

Strawberry plants will need either a strawberry mat around them or straw together with some form of netting to protect them. If space is a premium then use a strawberry pot. Use a 50/50 mix of peat base compost and John Innes No. 3.and put some crocks at the bottom of the pot for drainage. Feed regularly when the fruit has set and look out for red spider mite, aphis and grey mould on the fruits.

Rhubarb should now be harvesting.


Gro-bags and frames are ideal for outdoor tomatoes, peppers, cucumbers, etc. Feeding is also important so make sure you pickup some plant food as well.

The food analysis is given as percentages of NPK. Different percentages will do different things. ‘N’ (nitrogen) will give lots of leaf, ‘P’ (potash) will give good fruits and flowers, and ‘K’ (phosphate) will give good roots. A typical food for tomatoes and flowers will be 15:30:15 as NPK. Bonemeal for instance has an emphasis on phosphate for root development and used for trees and shrubs. Foods come in many forms including sticks to place in the soil around the plant for prolonged and metered feeding.

Tomatoes grown under glass will need their side-shoots pinched out. Feeding can start when they have set the first truss. As more trusses set, look out for magnesium deficiency in the leaves. Correct this with Epsom salts and water in.

Plant any remaining potatoes and earth up as required.


As the weather allows, place newly planted baskets, containers and so on outside, bring in at night if there is a risk of a late frost.


Houseplants will be due for potting-on into a larger pot. Try to move up only one or two sizes and use the same type of compost that the plant is in to re-pot. Many of the big leafy types will benefit from a light sponging of the leaves to remove dust and allow the pores to breathe. When the weather gets better, stand them outside in a sheltered spot. Providing it’s not too cold they won’t mind being rained on, even if the rest of us do!

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