What to do now - May

It's that time of year...

May and June are the months that transform our plots from mostly soil to an almost complete array of vegetation. They are very important months for keeping on top of weeds – these will be taking advantage of the longer days and warmer weather (by June there should be no risk of frost). They will be competing with crops for light and heat so regularly hoe and hand pick out weeds.

Earth up your spuds – applying earth around the base of potato stems will reduce tubers’ exposure to frost as well as keeping them in the dark to stop them turning green. Thin out direct-sown crops such as spinach, carrots and lettuce. Move leeks and brassicas to their final positions.

Keeping grow bags and potting compost in direct sunlight (or even in your greenhouse) will warm them up and give your seeds a head start in the growing cycle.

Keep an eye on your crops for early signs of pests or nutrient deficiency – e.g. if the leaves on your tomato plants turn yellow this is a sign of magnesium deficiency. This can be caused by overstimulating growth by using fertilisers with high content of other nutrients. This can be overcome by adding epsom salts (20g per litre, ½ oz per pint) to water every two weeks. 

Remember to ventilate your greenhouse on warm days, and consider using blinds or shades to avoid excessive temperatures, and damping down pathways to maintain moisture levels (and discourage mites).


Allotment tasks - May


Sow Now


Outdoors - Basil, beetroot, Brussels sprouts, cabbages, carrots, French and runner beans, lettuce, peas courgette, squash. 

Under cover - pumpkin, cucumber, sweetcorn, cauliflower, sprouting broccoli, aubergines, pepper. 



 Harden off plants (leave outside in the day and under cover at night). 

Ensure that growing plants do not dry up. 


 Broccoli, cauliflower, lettuce, spinach, spring cabbage, asparagus 

Protect Winter Brassicas


A well planned plot will have some well-developed brassicas as we head towards winter: various types of kale, cabbage, sprouts and broccoli. Give them a helping hand by:

  • Fitting mesh or netting to protect them from pigeons 
  • Stake out taller Brussels sprouts and broccoli plants
  • Remove any yellow leaves to discourage white fly and improve air circulation
  • Apply soft soap solutions to help protect against pests the following spring



Leaf Salad Crops

Salad crops develop quickly, and there are a wide variety – sorrel, lettuce, endive, kale, radicchio and mustard leaves - to suit various conditions.

They can be grown in seed drills, broadcast over an area of ground or grown in containers. Either way, they offer a fresh and tasty alternative to bags of supermarket salads.

As salad crops can outgrow weeds, watering and pests are the main concerns for salad growers. Watering every two days may be necessary during long dry spells if salad crops are grown in compost rich beds (daily watering may be necessary if they are grown in small pots).

Slugs are the main pest, and can be treated with pellets, nematodes, or regular picking off. Ants and aphids can also be a problem – ants can be kept in check if the surrounding soil is kept moist. Aphids can be squashed by hand if they are not tackled by ladybirds or beetles.

Regular collect leaves when they are ready to harvest. If leaves start to sag after harvesting they can be recovered by soaking in cold water.



Chitting Potatoes

February is  time to prepare seed potatoes for planting by ‘chitting’ them – storing them in such a way that they start to sprout before being planted in the ground. 

The potatoes should be spread out over a single layer in a cool, dry place which is free from the risk of frost. Large, unused egg boxes are ideal for this, allowing air circulation between each seed potato.

Ideally the storage area should be bright but the seed potatoes should be out of direct sunlight. After a few days the potatoes will then grow short stubby shoots which will help the potato plants to grow when they are planted out to get them off to a fast start when planted out. St Patrick’s Day is the traditional day of the year to plant potatoes.

There is some evidence that you can grow larger potatoes by breaking off the weaker shoots just before planting, leaving only the three or four stronger shoots to grow.