I made this Pre-pandemic for a "Starting plants from the grocery store" class I was teaching, here it is edited down for anyone interested.
For saving seeds, the fruit should be fully mature for the seeds to be fully mature. Therefore, you can use seeds from a winter squash but not a baby zucchini, and the likelihood that the seeds of a tomato (or red bell pepper) will grow are much higher than for a green bell pepper. Unfortunately, many are either going to be poorly suited for your conditions, or hybrid, which we'll touch on later.
Stem cuttings are a great way to start many common culinary herbs! Especially basil!
Some tubers to consider starting from are sweet potatoes and actual potatoes.
And then of course, the bulbs! Green onions and garlic are your best bets!
These are outdoor plants and thus are Somewhat Fussy if you're going to grow indoors. Do not overwater them (eg, letting them sit in a tray of water for days) nor let them dry out completely. Try to keep them evenly moist, with thorough waterings that then pour out the bottom of the pot unimpeded.
Given that they are outdoor plants, a south-facing window (assuming you’re in the northern hemisphere) or grow lights are your best bet. If they don’t get enough light, they will turn pale and stretch towards their light source. They won’t grow as quickly or as healthfully as they would with sufficient light.
Tomatoes & peppers! Tomatoes are the one that actually inspired me to make this because I saw this clip on starting plants from kitchen scraps, and they buried the whole dang half of a tomato! Don’t do that! What a waste of a tomato half! EAT your tomato! Take the seeds out!
If you’re intending to grow these outdoors, start them about 6 weeks before your last frost. If you have not grown plants from seed before, here’s some information from another class I taught: https://tinyurl.com/seedstarting2020
If you’re intending to grow them indoors the whole time, you will likely need grow lights for both tomatoes and peppers, and they like it if you keep your house on the warm side. I would suggest growing them outdoors and buying seeds for a dwarf tomato if you really want to grow indoors.
The down side is that most are hybrid, so when you grow out the seed, it's not necessarily going to grow well, be productive, or taste good. Even if it is open pollinated, it's probably been bred to thrive in conditions unlike those you can provide. If you need a successful crop, I highly suggest buying seed, or swapping with a reputable source. Although if you like and can find yellow pear tomatoes, those are an exception to this entire paragraph.
Basil! Basil is a great one to do stem cuttings of, get it started indoors, and then plant out once night time temperatures stay above 50f (10c). I prefer to start them straight into soil, and seem to have a higher success rate this way. To do this, remove all leaves except the top bud, and bury the stem in soil up to just beneath that bud and firm gently. Keep the soil moist and the pot above 60f, and you should have a good success rate. This method works for mint, lemon balm, rosemary, sage, etc, as well.
Green onions- really easy, put the bottom inch or so in soil and they’ll grow very well for you. I prefer soil over water because a) the water gets stinky, and b) they grow better and stronger in soil.
Sage, rosemary, and thyme (also any stemmed herb): just like basil
Lettuce, carrots, beets: you get the tops, but usually they’ll try to bolt. Easier just to buy seeds. If you want, I usually start in shallow water and then plant as soon as I see roots growing. Again, keep the soil moist, and for these ones, keep them in a cooler part of your house. But really, they almost always bolt in my experience.
Sweet potatoes: Get them in the fall, it takes months for them to start growing (unless you're somewhere warm apparently? ). They will sprout, grow roots, take slips to plant outdoors once night time temperatures study above 50f (10c)
Garlic, just grab a clove and plant in the fall. Boom. GARLIC.
Squash- you don’t know what you’ll get, because they might be cross pollinated with another variety or hybrids. If you do grow it out and it’s bitter, don’t eat it, it’s poisonous. If you want to know more, search “toxic squash syndrome”
Ginger: Plant the rhizome in summer, harvest before frost, or overwinter indoors with a lot of light.
Pineapple: Doable, but it takes three years to get a harvest. Plant in well draining soil, and give it as much heat and light as you can.
Just for fun: (Unless you’re in the tropics or have a lot of patience.)
Mango, avocado, citrus. Take years, and a different climate than I have to fruit. If you’re in the tropics, go for it, but know that avocado pollination can apparently be tricky. I am not in the tropics, so I do not have direct experience with this. Citrus I think I've read also don't come true from seed.
Apples, pears: take years, and don’t come true to type. You do not know what you’ll get, and you’ll probably get something that is not worth eating (but would work for cider). These do need a cold dormancy period in the winter to do well. Of course, you could plant them and then top graft if it does turn out they don’t taste good.
Plums, peaches, apricots: take years, often do come true from seed, but peaches and nectarines are very susceptible to peach leaf curl, so may just die depending on where you are.
