Saving seed for future planting is a time-honoured practice amongst growers everywhere. It can be more painstaking when deliberate cross-breeding is involved, but open pollinated crops tend to produce stable and reliable seed, with the exception of the cucurbits; more about the squash family to come.
For as long as memory serves I have been growing potatoes using my own seed tubers, with consistent yields from year to year. Arugula (rocket) is another where I use my own stocks, plus pole and dwarf beans, lettuce, cucumbers, caraway, dill and tomatoes. Here following are some notes on some of the more important crops; they all need slightly different treatment according to the nature of the fruit.
I always plant more than required in spring and allow a patch to go to seed. The bees enjoy the flowers. The plants do tend to get top heavy with seed pods and flop over, so that has to be taken into account. I can raid the seed producers for some leaves, although they do get quite spicy hot. Eventually the seed pods dry out and will shatter quite easily. Then I line a wheelbarrow or other container with a plastic sheet on a warm, windless, dry day, grab a sheaf of plants and thrash the tops against the side of the container so that the seed pods, grains and pod shells alike, are collected in the bottom of the container. It is really easy to run the resulting mix across a sieve of suitable mesh size to allow the grains to fall through and the chaff can go to the compost heap. One of the simplest seed saving exercises and generates lots of seed.
It is well known that squash readily cross-pollinate. Therefore saved seed will probably not produce plants true to type unless you grow only one type, such as zucchini or courgettes. There are also those who claim that growing different squash side by side results misshapen and odd coloured fruits in the current year. I have not seen it myself but I can imagine it might happen. I don't save my own seed for any of the squash family. Cucumbers, however, do not cross with squash so if you have only one type of cucumber such as the pickling type, saving seed is a good idea. Handle squash and cucumber seeds as you would tomato seeds as described below.
It is really curious how stable seed of tomato can be. I grow various types of open pollinated tomatoes side by side, save seed, and have them come back true to type each time. Grab a pound or so of ripe tomato fruit, squeeze open the fruit, let the seeds and juice fall into a container and separate out the large chunks of flesh that have no seed attached. Keep seeds and juice and use the lumps in the kitchen or take to compost. Put seeds with juice into large mason jar and add about half as much water as you have juice and seeds. Allow this mix to ferment for several days. Fermenting the juice helps the seeds separate from the pulp. After several days of ferment, separate manually as much as you can the seeds from the pulp. Add water, mix well and encourage the seeds to separate again. Repeat. Eventually most of the pulp is gone, pour off the excess water and tip the wet seeds onto a fine material such as the back of an old white shirt. The idea is to get the material to absorb the water and leave the seeds on top. Place in a ventilated area to dry fully. Once dry, store in a paper envelope or similar. Try to find an envelope which does not have a plastic clear window; the container is compromised if they shatter and your tomato seeds will get mixed up.
Saving seed beans is fun. When I grow Borlotti I look forward to threshing them with a flail. The key thing with beans is to make sure they are given adequate time to dry. Picked too early at shell bean stage they are vulnerable to crushing under violent threshing processes. When pods are burst by hand, keep beans in very shallow piles and keep them moving to avoid mold developing as they sweat out their moisture. You can judge dryness by feel (soft vs hard exterior) and sight (dull vs shiny skin) and sound (make a distinct clacking sound when poured from the hand when dry), or put 50 beans that you know to be dry on a scale and find the weight. Then take the same number of beans whose moisture content is unknown, weigh those and compare the weights. Don't store beans in a closed container until they are fully, fully dry. Each time you check the beans for dryness, also check for beans which look odd and discard them to compost.
Herbs can be fun. Dill grows rapidly in the right conditions, and produces large heads of seed. Pick at the right time and the seeds fall easily from the heads into a container, needing very little cleaning. It's all a matter of getting the timing right. Caraway is a bit more of a challenge. First it is a biennial crop, so you will sow it and let it grow in place for a year and a half. In the second year it sends up seed heads. Collect the seed heads when dry and separate the seeds from the heads. Caraway is not as easy as dill in this regard, so you will need to be inventive and patient. It pays to have lots of seed to play with. Caraway is a wonderful addition to bread. Also consider the annual coriander.Copyright © 2016