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Occasionally a courgette plant will produce extremely bitter, inedible fruit with high levels of cucurbitacin, which if they were to be eaten could make a person unwell.


Although rare, it can occur when a courgette plant is cross-pollinated by pollen from a wild or ornamental bitter gourd which naturally contains high levels of cucurbitacin to deter predators. This problem is only likely to occur with ‘open pollinated’ courgette varieties, where insect pollination produces crops in an open field environment. Although all possible precautions are taken to prevent cross-pollination, the arbitrary nature of this natural process means a small possibility remains.


A few cross-pollinated seeds could grow to produce plants that share the trait of the bitter gourd parent and it is this generation of plants which may then go on to produce fruit with high levels of cucurbitacin. These plants should be discarded as they will only produce inedible fruit.


The initial fruit from the cucurbitacin free, pure bred parent is still perfectly edible even if its seeds have been cross-fertilised. This means that all squashes and courgettes can be grown together without affecting the quality of their crops. However, because it is not possible to tell if the seed within a fruit has been cross-fertilised, it is best not to save these seeds for future plants.


We would always recommend using high quality, bought seeds, as commercial courgette growers will take all possible precautions to reduce the risk to an absolute minimum.


F1 hybrid varieties are pollinated in a controlled way and therefore their seeds are not at the same risk from accidental cross-pollination, although on rare occasions higher levels of cucurbitacin can be caused by a spontaneous mutation, as a response to injury or other external factors such as severe water stress.


Although exceptionally unusual in commercially available seeds, cross-pollination with bitter wild types was a phenomenon traditionally known to smallholders and kitchen gardeners who regularly saved seeds from harvested fruit. It was common practice for the first fruit from a plant to be checked by cutting a slice and touching it with the tip of the tongue. Fruit that is high in cucurbitacin is so very bitter it is instantly recognisable. The offending plant would then be removed and discarded. If the first fruit tastes fine, then the likelihood is that all other fruit from that plant will also be good.

Few gardeners these days save seeds from courgette harvests and the practice of the a ‘tongue tip taste test’ has become less well known, however it is easy to do and still good practice when harvesting the first fruit from a new plant.

 

What to do in your garden in May...

May usually brings us warmer weather and hopefully the end of too many night frosts, which will help us keep on top of those little gardening jobs. But just in case we get a cold night keep a piece of fleece close by to protect any of those tender plants.

1. Now that May has arrived, I like to make my first sowing of Runner Beans and Dwarf French Beans. I sow the seeds into 9cm (3 1/2 in) pots of multipurpose compost and place on the bench in a heated glasshouse or on a warm windowsill. This early sowing can then be moved into a cold frame once germinated, so the plants acclimatise gradually, before being planted outside towards the end of this month.
2. Further sowings of late Peas, Radish, carrot, lettuce and beetroot can be made into drills outside. This will ensure you get a continuous supply to harvest throughout the year.
3. If you didn’t find the time to sow some Half Hardy annual summer bedding earlier in the year, but you would still like a quick colourful display? The answer is sowing some Hardy Annuals. These seeds can be sown direct into the garden soil where they are to flower. These seeds can be sown anytime this month up to the beginning of June and will reward you with a colourful summer display. Try sowing some Nasturtiums, Sunflowers, Cornflowers, Godetia or Calendulas you won’t be disappointed.
4. Some of the early spring flowering shrubs will finish producing flowers this month and will soon begin to look untidy. To be sure of flowers next spring prune these shrubs quite hard after flowering. The reason for hard pruning is to encourage new young growth, which will help produce plenty of new flowers early next spring.
5. I love adding herbs to various dishes and salads. This month is the ideal time to sow some of the hardy and quick growing herbs like Dill, Coriander, Rocket, and Parsley. At this time of year the soil is warmer, so you can sow these seeds direct into the herb or vegetable garden outside in shallow drills, or into containers on the patio ready for harvesting later in the year.
6. If you are growing Strawberry plants in containers or the ground, this month they will start to produce a lot of flower. To encourage a good fruit harvest, I suggest you feed your plants with high Potash granular feed. Carefully work the feed into the soil in-between the plants, or the tops of the containers. Plants in the ground can then have some straw mulch placed around the plants to protect the developing fruit as it grows.
7. If you are growing Lilies in borders or containers, make sure you are vigilant this month as the dreaded Lily Beetles will be active munching on the foliage of Lilies. Adult Lily beetles are easily recognisable as they are an attractive bright red colour .The best method of control I have found is to keep a close watch over your plants and pick the lily beetles off with finger and thumb as soon as they are seen. Alternatively you can spray them with a suitable insecticide like the Ultimate bug killer (Provado). Remember Lily Beetle will attack any of the Lily Family including Snakes Head Fritillary.
8. Perennials are putting on a lot of growth this month, but before they get too large, it is wise to support them. Supporting them early when they are still only about 1/3 grown, will enable the new growth to grow through the supports and hide it, as well as stop any stems being damaged. I like to use old chicken wire, twiggy sticks or one of the manufactured plant supports for this job.
9. Around the middle of this month I will be planting up my containers and baskets with bedding plants. This will make space in the greenhouse and save a job later. I will then stand these pots and baskets outside on nice days and during mild evenings. If the weather turns bad they are put back in the greenhouse, shed or garage over night. When planting containers make sure you use good compost and add some slow release fertiliser, as these plants will be in this same container for several months. The slow release fertiliser will feed your containers and baskets for 6 months; so reducing the amount of liquid feeding you will need to do.
10. Towards the end of the month I will start to plant out some of my summer bedding plants into their final positions. This is only done once the plants have been hardened them off properly for a few weeks in a cold frame so they are acclimatised to outdoor conditions before planting