Your seeds should now be germinating like mad, so you will need to start thinning them. This means pulling out the weaker seedlings that have germinated very close to one another, allowing the stronger seedlings to grow with more space and less competition for water and vital nutrients.
At this point, It really does help to imagine the harvestable size of this vegetable and to keep focused on the reality of your space. Don't forget to eat the tasty little thinnings – you've just grown your own micro leaves!
Remember to continue to feed once a week with a liquid seaweed fertilizer as container plants don't have access to as many nutrients as those in the ground and they need this boost to keep growing productively.
If you are growing 'cut and come again' varieties of salad leaves, once they reach a decent leaf size – think the mixed bags you get at the supermarket – cut off the leaves with scissors, leaving at least 5cm of the stems remaining. This is really important as it's where they will regrow again and again, as long as you continue with the watering and the liquid feed process.
You will likely get four or five cuts per plant. To ensure a continuous supply, sow a few seeds every three weeks. It’s best to sow them in the cooler part of the day now the days are becoming warmer as they like to germinate in cooler temperatures.
Be vigilant: watch out for slugs and snails, and remove them – otherwise they'll devour the crop overnight.
Dwarf French beans are one of my favourites to grow as they're so productive. Make sure you use a container at least 40cm deep and sow direct during the first week of May.
Once germinated, keep them well watered and fed. It won't be long before you can start picking – if you are inundated, freeze them. Lightly blanch them for 2-3 minutes and fast freeze. It's as easy as that.
If you have the space, you must try growing courgettes in deep containers. Fed them and keep them watered and you'll be amazed at the speed they grow. At Petersham Nurseries we grow them especially for the flowers, which are stuffed before cooking – they're a staple on the summer menu.
As well as our own and branded seeds, we have a hand-selected variety of Kitchen Garden plug plants at the nursery – these are always a good option if you are short of the time needed to tend to seedlings!
Amanda Brame is deputy head of Horticulture at Petersham Nurseries, Church Lane, Petersham Road, Richmond TW10 7AB; petershamnurseries.com. You can learn more about growing an urban garden by attending one of Petersham's masterclasses.