If you intend on saving seeds, now is the time to start planning it.
Saving seeds is very satisfying because it’s like getting free food. After the harvest for bought seeds, you have used the monetary value. When you save seeds further on, it’s all free.
Make sure you are saving seeds from open pollinated plants, not hybrids. If you can get hybrids to germinate, the resulting plant may not resemble what you expected to get. This is especially true for things like squash. So, be aware of this when purchasing seeds for future seed saving.
You can try saving any seed but my favourite seeds to save are the following:
Peas- there are always pea pods that got missed in the harvest and I pull the plants, hang them in a dry spot and when the lingering pods have dried, shell them, leave them to dry further on a baking sheet then jar and label.
Scarlett Runner beans- these are easy to let a few get too big to eat and they are well able to be germinated the following year. Be sure to pick the seed pods before a hard frost so as to not damage the seeds. The best seeds are the huge purple mottled ones that release without hesitation from the pod when the pod is split open. Be careful to not accidentally slice the seed with your fingernail when opening the pod. Dry the seeds on a sheet then store in a jar. Use the same the method for other bean varieties such as black turtle beans.
Dill, fennel and onion- these all will go flying off the plant when they are fully ripe so JUST before that, I pick them and put them into paper bags, then you can catch the seeds as they fully ripen and fall from the plant. Otherwise, they just reseed all over the ground which is fine but you have to move them to where you want the plants in the spring.
Garlic- the key to saving garlic for seeds is in the harvest. Garlic is picky to harvest so that it lasts in the pantry until the following year. I pick the scapes when they have done 2 full circles but not yet begun to uncurl again. Then, stop watering the garlic 2 weeks before harvest, so the paper covering has a chance to develop. Hang them in loose bunches out of the sun in a breezy spot outside until they are very dry and the green tops are all brown. Then, trim the roots, and store inside in a cool, dry breezy spot. Choose the heads with the largest cloves to plant later that year a couple of weeks before the ground freezes just so they can develop roots but not grow up out of the soil.
Marigold, Nasturtium, Coreopsis, Morning Glory-(NOT wild bindweed)- these flower seeds are all easy to save, just don’t deadhead the tops you want to save for seeds and wait until they are very dry, gently pull the seed heads into your palm and carefully rub the seeds from their casings. Make sure they are fully dry, then jar and label.
Carrot, Beets, Parsnips- the seeds from these plants don’t develop until the second year so you have to leave your desired plants in the ground and let the plant grow again in the spring. Then, let the plant go to flower and save the seeds from that. You usually will need to save many more seeds than you think you will need because the germination rates are a little lower for these plants.
Potatoes- You can just let a few missed ones grow the following year but this does not allow for crop rotation and often the missed potatoes are small and don’t make good plants the following year. Save some perfect undamaged large potatoes until the following spring. Chit them, that is let the seed potatoes sprout a tiny bit in the light before planting them. Most storage potatoes will have started to sprout in the spring anyway. I have found that planing the whole potato and not cutting it into separate eye/sprouting sections results in a bigger and more robust plant. Keep in mind that buying and planting certified seed potatoes does help prevent potato diseases from persisting year to year.
Sunflower- make sure you let them fully ripen on the flower head so the seeds come off with only a gentle coaxing.
Walking or multiplier onions- these are great, they do their own thing but have to be re-situated as they will end up where they want.
Plants to be wary of: mustard, common oregano and mints, will all end up taking over your yard with no help from you. Be aware of this if you want to grow these plants.
C1/B2: 
A1/A0: 
