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 crops 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 might be able to get a crop by choosing a fast maturing variety - or the easiest solution is to buy a plant).

Most of the crops listed below can also be sown in June and July. So if you don't have time (or space) to sow them this month, you can delay them for a few weeks. If you have lots of pots you can have fun making a plan of what you will sow when in order to maximise the productivity of your space.
  • 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.

    Soaking runner beans in water overnight before sowing can speed up the germination process. Soaking runner beans in water overnight before sowing can speed up the germination process.


     
  • Courgettes, 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.
  • Peas, mange tout and broad beans: sow outside in their final pots - until mid July. (Tip: broad beans that are sown later in June can be less prone to black fly).
  • 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 sow at least one tray of salads every month - seedlings that are not needed in the pots are harvested and eaten!  Until mid-September.

    If you sowed salads or oriental leaves earlier in the year they should be ready to harvest now. If you pick off the outer leaves, you can usually harvest them over several weeks. But when they bolt or get tough, you'll need to replace them with new plants. If you sowed salads or oriental leaves earlier in the year they should be ready to harvest now. If you pick off the outer leaves, you can usually harvest them over several weeks. But when they bolt or get tough, you'll need to replace them with new plants.
  • 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.
  • Herbs: now is a good time to sow basil, parsley, chives, dill, lovage and shiso. Some herbs are tricky to grow by seed. They're better 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).

On the left are pea sticks – these can look great and are perfect for shorter varieties of peas. If using poles like on the right, you’ll probably need to tie the peas to the poles every couple of weeks, so that they are well enough supported. On the left are pea sticks – these can look great once covered in peas and are perfect for shorter varieties. If using poles, like on the right, you’ll probably need to tie the peas to the poles every couple of weeks, so that they are well enough supported. For tall varieties of peas, poles or pea netting are good solutions.


 

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


 

Planning watering for the year

Now can be 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. 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!

Earth up potatoes

As your potatoes grow, add more soil, leaving about a foot of leafy growth sticking out at the top. This will encourage more potatoes to form.

Bags are handy for growing potatoes - you can simply unroll the bags as the potatoes grow and pop more soil in the top. These are old recycling bags. Bags are handy for growing potatoes - you can simply unroll the bags as the potatoes grow and pop more soil in the top. The ones on the right are a couple of weeks further on. These are old recycling bags.


 

 

34 comments

Rachael
 

Very good. Thanks for timescales on sowing seeds. Very inspiring.
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Mark Ridsdill Smith
 

Hi Rachel, really glad to hear that the timings are helpful for you. Mark
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Lora
 

I have a question. I'm not that fond of peas but like sugarsnaps and mangetout. I have a packet of pea seeds already as I've been growing them for shoots. If I sow some but harvest early would I get sugarsnaps or should I get a variety for that purpose only?
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Mark Ridsdill Smith
 

Hi Lora, the varieties sold as sugar snaps and mange tout are bred for their soft, tasty pods - so if you want to be sure of this, it is worth buying them. If you've got one or two of you "pea shoot" plants already growing, it would be worth leaving them and picking the pods small - you might get a nice surprise! If you do try that I'd be interested to hear what you find.
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Nancy
 

While the blogs and seasonal tips are out of sync with us in the southern hemisphere they are a good inspiration as to what we can do. I am planting out the winter crops but still enjoying the strawberries hanging in containers along the fence line and just picked my first crop of mandarins from the dwarf tree in a big pot. I've trimmed back the strawberry guavas espaliered against the BBQ shed that has been producing from a pot for 6 years.I have just planted the early garlic in a styro veggie box ,the 3rd garlic planting so they are staggered when they mature and I always have garlic ready .The box of tatsoi,and another of red and green oak leaf have been set into larger containers from the nursery pot, and the Asian greens and lettuce that I planted 2 months ago around the bottom of my dwarf pomegranate tree are in the stir fry and salads a couple of times a week.
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Rhys Jaggar
 

Mark I have some Kale and Chard seedlings needing to be potted on/out into the garden soon. This is the first time I've grown either. If I were to grow a couple of each in pots, will they grow well in a 20cm diameter pot?? Not sure how deep a rooting system either needs....... Cheers Rhys
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Stephan
 

The annual cold spell of mid-May, much feared by fruit farmers, has hit the continent almost in time this year. So we can hope for warmer days and more sowing soon. Traditional beginning is today, 12th May, St Pancras Day (!). The cold began only one day earlier. So it should be over by 14th.
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Mark Ridsdill Smith
 

Hi Rhys, 20 cm pots will be fine. Chard and kale can be grown successfully in a wide range of pot sizes and spacings. Close together in a small pot for small leaves or further apart in larger pots for bigger leaves. I've got a chard plant at the moment sitting on its own in a nearly 50cm pot and its growing pretty huge! But normally I'd grow 6 - 8 plants in a 40 cm pot for medium sized leaves. Mark
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Izumi
 

I'm finding this "Keep a beady eye out for pests" really hard this year, as there seem to be LOADS of baby slugs & snails! They measure as small as 2mm and still can eat a lot! I had so many seedlings appearing, and then over one night they all turned into just stalks... I also found a lot of centipedes feasting on peas and beans in the ground. (I dug up some of the peas as I thought they were taking a long time to sprout). A pea looked like a swiss cheese, and there were about 5 tiny centipedes inside! I will persevere though...... :-)
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TinCat
 

Hi - am loving the website! My chard seedlings are just about surviving the deluges in North Wales and the runner beans are coming along a treat. I'm hoping someone here will be able to give me some advice on how to secure wigwams or other support for the runner beans to the pots they are growing in. My growing area is exposed to the prevailing wind and half way up a mountain so am worried wigwams will be blown over taking the beans with them. Any ingenious tips? Hwyl pawb!
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Jordan Wood
 

"Making wigwams for runner beans" ... such a May ritual!!
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Donna
 

What an awesome blog Mark! I will be coming back for inspiration as my garden gets going. I've already put to good use post on sprouting. Thank you.
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Ange Sampson
 

Hi, I always put a horizontal cane connecting the wig-wams ( through the crossed ends ) and anchor it to the ground with a length of rope and a heavy duty tent peg...let the wind blow !
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Wendy
 

I'm really enjoying your blog Mark! You have some great information here, thanks for sharing!
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Mark Ridsdill Smith
 

Kind of you to say that, Wendy, and motivating to here. You are growing in Australia I guess from the title of your website?
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Valerie
 

Love that tip about growing spuds in a bag and unrolling it, adding more soil as they grow. So practical, and so easy to harvest your crop when ready.
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Caroline
 

lots of super info here Mark - thanks a lot for some great inspiration!
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Mark Ridsdill Smith
 

My pleasure, so glad you found something useful here, Caroline.
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Dru
 

Hi..I have a small terraced garden, sheltered by an old high wall and east facing, and I'd love to grow a courgette. But I don't have any sunny horizontal space left! . Is there any way to grow one vertically? Someone suggested an inverted tomato trainer?! Have you any ideas? Many thanks 😊
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Mark Ridsdill Smith
 

Hi Dru, there is a courgette variety called 'black forest' which is supposed to climb - it does a bit, but I wouldn't call it a prolific climber. I tend to grow tromba (also called tromboncino) squash instead. It's a squash rather than a courgette but the taste of the small fruits is similar - and it IS a vigorous climber. You could climb it up a string.
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Dru
 

Ah many thanks Mark..That's great advice (as usual 👍) ! All the best Dru
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Karina
 

Have you tried growing Asturian Tree Cabbage. I have some seedlings which I have grown from seeds and was curious to find out how other people got on with growing them.
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Mark Ridsdill Smith
 

Hi Karina I've tried tree spinach but not tree cabbage! Others may have tried it in containers? Let us know how you get on - it looks an interesting one.
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Jim Robinson
 

Hi Mark, thanks for the advice on sowing and harvesting salads. I tried last year but sowed them all at once and then they were overcrowded and then they bolted. So disappointed that I haven't bothered this year. You have inspired me that there is still plenty of time. Just spread the planting out. Really good advice, thanks again.
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Mark Ridsdill Smith
 

Your welcome, so glad to hear it was helpful. Hope they grow well this year.
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Moyra Elder
 

At almost 90 I am beyond doing much in the garden but thought I'd try tomatoes for the first time; bought three plug plants and put all in one pot on the sun-room windowsill above the radiator. They seem OK but I wondered when to put them into three separate, larger pots. Should I keep them there or eventually put them outside? We're in the far northwest of Scotland on the coast where the prevailing wind is from the southwest; there's space on the south-facing wall where they could go into a fish-box.
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KATE WILLIAMS
 

Hi Mark. Interested to see the microgreens article. I love peas but find them hard to digest. I'm wondering whether microgreens would be better?
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Mark Ridsdill Smith
 

Worth a try, I would guess? But I should add that I'm not a nutritionist and cannot offer professional advice in this area!
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Mark Ridsdill Smith
 

Well done for getting this far. I'd keep them inside for the next few weeks and then move them out in June when hopefully it will be warmer. Generally tomatoes do best with one plant per pot - ideally about one 20 litre pot per plant although 10 -15 litres is also ok. You could grow three plants in a larger pot - say 50 litres, but it will be easier to manage and look after them in separate pots I think. Good luck!
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Moyra Elder
 

Thank you so much; I shall follow your advice and leave them for a while yet. I'm thoroughly tired of the only tomatoes I can buy here: tasteless, thick-skinned. Soon I'll plant coriander seed indoors and hope for the best. In the past I've grown your peashoots and enjoyed them.
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Martina NUGENT
 

Hi Mark, Delighted to have found your fantastic newsletter. I planted 7 seed potatoes in a canvas grow bag. Some of the seeds didn’t look great so I just put them all in one bag. All have come up should I just take the smallest ones out to leave more room
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Mark Ridsdill Smith
 

Hi Martina, yes, I’d take all the smaller ones out, otherwise it will get too crowded in there. You could maybe move them into another bag if you have one.
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Martina NUGENT
 

That is brilliant Mark thank you. I have another bag so will split them.👍
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Maria
 

Just took my tomatoes out doors in pots,i likes what you have to say on how to care for them. Will keep up with what you have to add on snow peas. Thanks
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