All the members of the same species can cross with each other and are pollinated by insects and so need to be separated by 800 metres. As a result, the only reliable way to save their seed from more than one variety of the same species is to pollinate by hand before the insects do and then keep the insects away. This is done by wrapping masking tape or a freezer-bag ‘twisty’ around those male and female flower buds, which show signs in the evening of opening the next day. The purpose of the tape is to ensure that the flowers do not open and get pollinated before you arrive. Mark the taped flowers with a cane. The following day after the dew has dried off, pick the male flower (this is the one without the tiny immature fruit beneath it) and tear off all its petals to uncover the pollen-bearing stamen. It is best if you leave a reasonable length of stem on the flower when picking it so you can hold it in your teeth while stripping the tape off the female flowers. Immediately you have the tape off, rub the stamen against the style of the female flower and then tape up the petals again so that insects are kept out. One male flower can pollinate several females. Mark the hand pollinated flowers so that, when the crop is picked, you know which are the fruits from which seed should be collected and preserved.

Seed can be taken from squashes, marrows, melons and pumpkins when they are picked for eating. Squash seeds develop for some time after the fruit appear mature and should be left for a couple of months after harvest in a warm dry place while this happens. Cucumbers need to be allowed to go soft on the vine before being picked for seed extraction. Leave the cut cucumber for two weeks before scraping out the seeds and separating them from the gelatinous liquid in which they are bathed by allowing the mixture to ferment in a large bowl in a warm place for three or four days, stirring from time to time. (The smell is truly foul). Then fill up the bowl with water and stir. The good seeds will sink to the bottom. Pour off the liquid and rinse the seeds in more water before placing them on a tray or plate to dry in a warm, well-ventilated place. Likewise with courgettes, the fruit must reach maturity, ie they must be bigmarrows with hard skin before the seed is ready to harvest. Then like other squash varieties, the seed may be separated from the fruit and can be washed and put on a plate to dry straight away. Never allow the drying temperature to exceed 32 degrees C. The seeds are dry when a sample snaps in two when you try to bend it. They do need to be dried fairly quickly or they will go mouldy. A fan or blower heater on a low heat is helpful if the weather is damp. Keep them in a labelled airtight jar. They will last for 5-10 years. It is best to store winter pumpkins for several weeks before extracting seed to ensure proper germination the following season.