What to do in May

May is a busy and fun month in the container garden: you can sow most crops directly outside now, seeds germinate more easily, and everything just grows!

This month

1. What you can sow now
   
   
2. Other jobs for May

• Tying up peas.
• Making wigwams for runner beans
• Planting out, pinching out and supporting tomatoes
• Planning watering for the year
• Feed wormery more as weather warms
• Keep a beady eye out for pests
• Earth up potatoes

1. What you can sow now

You can sow most things this month - the main exceptions are those that take longer to mature, like aubergines, chillies and tomatoes, as they may not ripen and produce fruit by the end of the season. (If you haven't sown these yet you can usually pick up plants from community plants sales and garden centres in the next month or two). 

Most of the crops listed below can also be sown in June and July. If you don't have time (or space) to sow them this month, you can delay them for a few weeks. 

• Runner and French beans: sow outside in the final pots or inside (to protect from slugs) in large modules. Climbing varieties of French beans will usually give you a higher yield from containers than bush varieties. Sow until early July. See How to Grow Runner Beans in Containers.
• Courgettes / zucchini, cucumber, squash, fat baby achocha: sow in small pots (one per pot) and transplant once the second pair of leaves have developed or sow straight into their final pot once all risk of frost has passed. Sow until end of June. See How to Grow Courgettes / Zucchini in containers. 
• Peas, mange tout and broad beans: sow outside in their final pots - until mid July. 
• Carrots, beetroot, turnips, potatoes, spring onions, radish: sow outside in their final pots - until end of  July.
• Salads: cut and come again salads (like lettuce, rocket) may bolt and become tough and bitter to eat as the weather warms. Good watering and a slightly shady spot can delay but not prevent this. To get round this, keep sowing salads so that you have a constant supply of seedlings to replace tough, old specimens when needed. I try to sow a tray of salads each month - seedlings that are not needed in the pots are harvested and eaten!  
• Oriental leaves: oriental leaves like pak choi and mizuna can be sown now. They grow fine even if they can bolt (flower) and go to seed quite swiftly at this time of year (the increasing daylength causes this). Picking off (and eating) the flowers can extend the time the plant produces leaves productively. Tip: if you wait and sow these leaves after the mid summer solstice (when days start to shorten), they will be less prone to bolting. Until mid-September.
• Chard, kale, spinach: keep sowing. Until mid-August.

Chard sown now can give you leaves all year round. This pot of chard was sown in May last year.
It will bolt (flower and go to seed) soon,but it has given us leaves for a full year. 

• Herbs: now is a good time to sow parsley, chives, dill, and lovage outside and shiso and basil inside. Some herbs are tricky to grow by seed and easier to buy as plants or grow from cuttings. These include mint, rosemary, thyme, lemon verbena, tarragon and Vietnamese coriander.

2. Other Jobs for May

Tying up peas

Peas need more support than some crops to climb successfully. 'Pea sticks' - sticks with lots of small branches - are an attractive solution if you can find them - not always easy in a city! Or you can buy pea netting or make a wigwam with sticks or canes. If using a wigwam, you'll probably find the peas need regular tying up to prevent them falling over (be particularly sure to do this if strong winds are forecast).  

Any sticks with small twigs for pea tendrils to cling on to will work as pea sticks. 

Make runner bean wigwams

Runner and French beans are enthusiastic and strong climbers. They need a good strong support - like a wigwam - to climb up - and they'll be off! You can have fun making a beautiful wigwam. Locally coppiced bean sticks add a a nice rustic feel if you can find them, or you can use canes which are widely available.

Planting out, pinching out and supporting tomatoes

Move tomatoes to their final pots outside once all threat of frost has passed in your region. If you're growing vine tomatoes, you'll also need to pinch out the side shoots (these appear at the junction between the main stem and each leaf). You'll also need to create a solid structure to support the vine. You can use a simple cane (if you can secure it firmly), build a tomato cage, or, a personal favourite, use strings attached to a wall above the plant. In my London flat, I attached the strings to eyes screwed into the brickwork at the top of my windows and then wound the tomatoes round the strings as they grew. This worked great, supporting the tomatoes, even in strong winds.

Strings provide good support for vine tomatoes if you can find a point to attach them.

Planning watering for the year

Now is a good time to think about how your plants will be watered over the summer, on days, weekends or weeks you are away. You might set up an automatic watering system, ask friendly neighbours, or book friends in to house sit while you are away. Or just grow stuff that will all be ready to eat before your holidays.

Feed wormery more as weather warms

If you have a wormery, you'll be able to feed it more waste food as the weather warms. If you can find a supply of well rotted manure, now is also a good time to add an inch or two to the top of your wormery. The worms love it (it introduces all sorts of beneficial bacteria) and it will encourage them to breed. If you find the worms are eating more than you can feed them (unlikely but possible particularly if you have several wormeries), you can often find additional food for them in the city -  scraps from your local cafe for example.

Keep a beady eye out for pests

If you can catch any infestation of pests early, you can often keep them under control by simply squashing them with your fingers. Here are some aphids I found guzzling on my aubergines.

If you can catch aphids early you can often keep them under control by simply squishing them with your fingers.

These are on my aubergine plant - they seem to love aubergines!