Of all the plant parts we eat the most generally nutritious are probably the seeds. All the requirements for new lives are packaged inside and most seeds are thus very rich in nutrients as well as carbohydrates and or fats. World-wide we survive on seed crops, and their derivatives. Many are grown on an immense scale such as wheat, barley, rice, maize etc. In general these are hardly practical on a garden scale, it's not that we can't grow them but that they are awkward to harvest and process, and we need far greater quantities than most kitchen gardens can supply.
We often grow some bulk seed crops though such as peas and many of the beans. Broad beans are usually grown for their fresh seed and not their pods, French and Haricot for the fresh pods and dried seed and most people eat runner beans only for the fresh pods and never their seeds. However I find the latter really chunky in winter stews. We can even grow (only just) another leguminous seed the soybean which is particularly rich in protein. It really needs to be grown under cover. but is worth it as very tasty. However like the cereals these pulses are barely worth growing where space is limited as they do take large amounts of ground to give worthwhile crops.
Many other sorts of seeds are used culinarily, these are often the more expensive to buy and hard to find fresh and of good quality. Perfect choices for the kitchen garden are such as celery seed, poppy seed and coriander to name just a few. Most are easy to grow and need little processing before use which makes them more practical for the small household. After all few of us are going to find it feasible to grind our own flour, to say nothing of how to separate the grain from the heads first. Mind you growing the wheat is not difficult, but there is an edge effect where wild birds deplete the harvest in a belt around the edge. This doesn't matter much on a field scale but in the garden it is fatal.
Indeed a major problem facing seed growers is bird damage as so many small birds eat seeds and will not be stopped by anything other than netting. Of course if you want to feed wild birds then some seed crops such as sunflowers are going to be perfect winter provisions for them and can be grown especially. (and most berrying shrubs and teasels as well) Wheat is very easy, and good for my hens too.
Most seed crops we want to grow are remarkably easy and obliging. We are asking them to do what most plants want most; which is to set seed. For example look at the alarming tendency of so many vegetables to bolt and rush to seed if ever given a check to their growth. When we are growing crops for their seed it does not matter too much if they bolt although the yield is somewhat depressed. If you crowd the plants; the total crop is not too badly affected but individually each plant gives less, so the work to harvest the seed goes up with more smaller less well filled pods to handle.
More space per plant is always a good option, it makes for the healthiest plants and is far better at getting a good crop than applying nitrogenous fertilisers. These should not be given to most crops grown for seed as high fertiliser applications make for rank soft growth. A little potash may be useful on very poor soils though as if this is short then flowering and seed production may be limited. Setting a heavy crop of seeds takes a lot of nutrients out of the soil so it is wise to add compost or manure once a seed crop has been taken from the soil -especially after poppies.
Poppies are certainly one of the most competitive and demanding crops you can grow for their seed, however you do not need grow many plants to make a lot of seed. And as they are so attractive they can be grown in the flower garden. They are of the simplest cultivation; I sow in late summer or autumn and the plants over-winter. (In hard frost areas they may need spring sowing instead.) The seed is so fine it is safest broadcast over raked soil and then just protected with wire guards till the seedlings can be thinned. Little bothers poppies and they are lovely in flower. They are also potentially poisonous and a source of opium but their cultivation for flower or seed is legal in the UK. You also want to have the right sort for baking; I sowed seed of supermarket poppy seed for my first batch and saved my own since then. I find poppy heads store best hung in the ceiling of my kitchen. As each capsule is sealed the seed does not pick up any taint from the cooking smells in the air and the portion control is perfect with one capsule just right for a small loaf of bread.
Celery is rather too easy to grow for the seed. The plants bolt almost unfailingly at the first signs of drought. I find there is little difference in flavour between celery and celeriac seed so the easiest plan is just to grow a few extra of either of these plants, let them overwinter and in the second year they immediately flower and set seed. Theoretically you ought to be careful of other umbellifers flowering nearby as they might cross-pollinate, in practice this does not seem to happen. I find the seed cleaned and stored in a dark jar keeps fresh for years.
Mustard is easy to grow but you must get the right variety; again using supermarket seed can at least give you that. Often it gives poor germination but mustard does multiply marvellously. I find the seed is easiest got from the pods by thrashing them on the dried plants in a paper potato sack then sieving and winnowing. It is easy to use the seed for French style grain mustard but hard to grind and sieve it down for yellow English.
Coriander is very simple but you need be careful you are growing a variety selected for seed use; I used supermarket seeds which were poor to germinate but gave me the first plants. The seed varieties have a distinct citrus tang to the seed which is much relished in Eastern dishes. Some sorts of coriander seed on sale for sowing are for leaf varieties grown to chop with salsa and curry dishes. There is nothing wrong with these but I find their seed does not taste quite the same. The round seeds are easy to clean and store but need crushing to release their flavour before cooking. It can be sown direct in spring in warm soil or under cloches and does not get very tall so can stay under them in bad years.
Cumin and Dill can likewise be grown outdoors from early spring if started off under cloches. For the former the seed is not widely available from all seedsmen but again the supermarket usually has whole seed and some will germinate. Both these seeds are so much better when home grown; their taste is much cleaner than with the bought items. And dill seed goes so well with cucumber pickles!
Caraway is more difficult to grow, it resembles carrots in many ways and needs to be grown like them but in a warm patch to over winter successfully as it is a biennial and will only flower and set seed the second year. If it bolts the yield is dreadful. It needs to be carefully dried and is wonderful made into a traditional seed cake.
Nigella seed is not often grown or sold in Britain, it is a delicious addition to sweet baked products especially things such as Danish pastries. In the middle East special varieties have been bred for culinary use but I eat the ordinary garden form of Love-in-a-mist seed and have not suffered though apparently we must be cautious of this seed. Again like poppies the flowers are so pretty they can be grown in the flower garden. The only problem is separating the seed from small bits of the dried seed case and flower.
Sunflower seeds are very health giving. The plants are so easy to grow -and hardier than you would imagine, they can be direct sown in very early spring. I used to save the seed on the heads tp feed my chickens and the wild birds but now I toast and eat much of them myself. I wish someone would breed a hull-less seeded variety or one with really huge seeds.
There are hull-less seeded pumpkins; one is called Lady Godiva. Pumpkin seed is very rich in nutrients and far better value than the pulp around it. And they are so easy to grow. They are a must in any garden. When ripe the seeds and pulp are scooped out, the washed dried seeds keep well and can be nibbled, added to salads or baked in bread.
Amaranth is an interesting plant with many different forms with ornamental, spinach-like and seed uses. The seed is minute but the plants are amazingly productive so they are worth growing. They need careful shallow direct sowing in warm soil under a cloche to start with and a good summer. I eat the seed popped like corn then eaten with honey and yoghurt. The plants get several feet tall, do not need staking but need gathering before all the seed ripens fully and drops off.
Nasturtium seeds are rarely gathered but whilst still soft they can be salted and pickled in vinegar. They are better than capers which they somewhat resemble. They are such a tasty addition to pizzas, salads and hors d'oeuvres that everyone must try some! The trailing varieties are best and the flowers and leaves are good in salads as well.
Of course there are so many other seeds we can eat. I quite like nibbling the hard oily seeds of the Milk thistle Silybum marianum though I'm not even sure they're edible and I chew on the long poddy seeds of Sweet Cicely for their sweet aniseed flavour when I'm thirsty. Anyway that's enough for now, I'm off for a cup of hot water extraction of roasted coffee seed.