Updated: Nov 7, 2021
Tender plants can be moved outside
Depending on where you live in France, at some point in May your tender plants can be safely moved outside. Where I live, in SW France, the latest frost I have known was around 26th April one year – which was catastrophic for vignerons – so I start to harden off plants in the last week in April and then move them out into their permanent positions at the beginning of May. If you live up a mountain, in the middle of the Massif Central or in a notorious frost pocket then you may need to delay this by a couple of weeks. Hardening off simply means gradually acclimatising plants to colder outdoor temperatures. I do this by first moving them to a sheltered spot outside during the day and bringing them in at night. I then move them to a more exposed spot during the day and move them back to the sheltered outdoor spot at night. This all takes about a week after which I feel that the plants are sufficiently acclimatised to go outside into their permanent position (but I always have some fleece handy for the most delicate plants for a few extra weeks – just in case). A sudden frost can be a killer, but equally likely to do serious damage is a sudden, heavy downpour or – worse – hailstorm. Young plants still trying to establish themselves or still in pots can be destroyed by a five-minute flash storm.
Summer vegetables can be sown with confidence
Once risk of frost has passed you can also sow all of your summer vegetables – beetroot, summer salads, French beans, maincrop peas and mangetouts, sweetcorn and – dare I say it – this is probably your last chance this year for sowing winter leafy vegetables such as Brussels sprouts, winter cabbages and cauliflowers.
Prune spring flowering shrubs
Shrubs which flower before the end of June should be pruned immediately after flowering as, next year, they will flower on this summer’s growth. So now is the time to prune Forsythia, Ribes (flowering currants) early flowering shrubby honeysuckles (such as Lonicera fragrantissima and, if you have not already done it, winter flowering jasmine.
In most areas of France roses hit their peak in May. Flowering takes a lot of strength out of the rose, so once that first flush is over give them a good feed with a proprietary brand of rose food, tomato food (which tends to be cheaper), liquid seaweed or a home-made fertiliser made using comfrey. If you do not want to keep the seed heads then dead head your roses regularly. This stops energy going into seed head production and also promotes successional flowering. Some roses (such as Rosa moyesii) have ornamental rosehips so do not deadhead them as they will make an important contribution to your autumn garden.
May usually has that combination of wet weather and warmth which promotes leafy growth and nothing seems to grow faster than a weed – so weed often, especially after rain when the ground is soft and you are actually able to get the little menaces out of the ground by the roots. In dry weather I can end up resorting to pulling the top off a deeply embedded weed which at least checks future growth and removes potential seedheads before they can do their damage.
Deadhead herbaceous perennials
This will encourage the plant to continue flowering. A plant’s purpose each year is to flower and set seed, thus creating offspring. Once it has done that it has no further need to flower. If you remove spent flowers before they are able to set seed you oblige the plant to flower again – and again – as it attempts to create and set seeds.
You can also remove the remaining leaves from spring bulbs once they are all brown (but not before). As far as pots of tulips are concerned, I remove the seed-heads as soon as the petals fall and then move the pots to an unobtrusive corner of the garden. Once the leaves have all died back I lift the bulbs from the soil and store them in a cool, dark, mouse free place until the end of the autumn, when I replant them in the ground – either in a flower bed or in rough grass. I use the spent soil as a mulch over areas of heavy clay soil to help condition it.
Finally – if May turns out to be a scorcher – don’t forget to water whenever necessary. Plants in pots are like pets – they are entirely dependent on you for sustenance. Without regular food and water they will die.