First up:
Sources for seeds/plants:
https://www.johnnyseeds.com/
https://territorialseed.com/
https://www.morgancountyseeds.com/
https://migardener.com/
https://www.southernexposure.com/

For fertilizer, I tend to use a combination of synthetic and organic feed.  I use compost plus things like mixes made from blood meal, guano, alafalfa and kelp meals, etc.  Along side that I will use synthetics.  I have urea and ammonium sulfate, triple super phosphate, and potash and mix them for what I need.   When my seedlings are well into the true leaves I will do a few feedings of Peters (aka Jack's) Water Soluble Fertilizer.  A tablespoon per gallon and that gallon will feed a decent amount of 10/20 trays.
https://www.greenhousemegastore.com/supplies/fertilizer/jack-foots-fertilizer-20-20-20?dfw_tracker=43186-FE-JP-2020

Alfalfa Meal:
https://www.amazon.com/Down-Earth-Organic-Fertilizer-2-5-0-5-2-5/dp/B000CO7ZYI
Kelp Meal:
https://www.amazon.com/Down-Earth-5-Pound-1-0-1-2-7813/dp/B000COBZBM
Feather Meal:
https://www.amazon.com/Down-Earth-Organic-Feather-Fertilizer/dp/B001B2W842
Bat Guano:
https://www.amazon.com/Roots-Organics-Nitro-Fertilizer-3-Pound/dp/B007TFYGG8/
Crab Shell:
https://www.amazon.com/NeptuneS-Harvest-Cs604-Organic-Multi-Purpose/dp/B016794H7E
Blood Meal:
https://www.amazon.com/Espoma-163680-Blood-Organic-Fertilizer/dp/B074F3SYZS
Urea:
https://www.amazon.com/Easy-Peasy-Urea-Fertilizante-Alimentos/dp/B071WCW6P7
Ammonium Sulfate:
https://www.amazon.com/Hi-Yield-Ammonium-Sulfate-AMMONIUM-SULFATE/dp/B000OV85BQ
https://www.amazon.com/Ammonium-Sulfate-Easy-Peasy-Plants/dp/B07BTPJCT5
Super Triple Phosphate:
https://www.amazon.com/Triple-Phosphate-Easy-Peasy-Plants/dp/B075BY4GSF

For premixed organic fertilizers, I really like Vermicrops offerings but they are too pricey for me to recommend.  Their Vermiall, Vermiveg, and Vermibloom offerings really have worked out well but for those wanting to grow more than a novel amount, roll your own mixtures.
https://www.vermicrop.com/vermiall
https://www.vermicrop.com/vermiveg
https://www.vermicrop.com/vermibloom

Home Depot seems to be carrying a brand of 10-10-10 called Hyponex.  I have not tried it but if you can find it at a local indie nursery or some such, give it a shot and report back.  Hyponex doesnt seem to have a website for the fertilizer at this time so.. you will be going in blind.

Fertilizer manufacturer sites:
https://www.easypeasyplants.com/
https://downtoearthfertilizer.com/products/
https://www.fertilome.com/Hi-Yield-Products.aspx
https://www.neptunesharvest.com/products-for-all-other-customers.html
https://www.aurorainnovations.com/roots-organics-dry-nutrients
https://www.vermicrop.com/fertilizers

Anti-Pest Stuff:
Neem Oil    
+
Wettnig Agent
= Dead bugs that no longer eat your plants.  
"Natural plant killer combo (kills foliage only): 40% industrial vinegar mixed with 50/50 water and add 2 fl oz orange oil. Apply during the heat of the day in full sun when leaves are dry and ready to absorb moisture. Doesn't work with nettles so well, but works on grass and other broad leaves such as dandelion, feel free to try on stuff. Indiscriminant, don't spray on stuff you like. Kills raspberry leaves dead in a hurry."
H/T Rat_Patrol

Some things have wonky prices in teh Amazon links.  They are likely just not available so.. search elsewhere.  Ace Hardware tends to have a lot of independently owned stores as well and may have some of the odder listed fertilizers.

As always, before the season.. get your soil tested. Knowing what to add amendment wise before planting helps immensely.  Your local extension will have links for such a thing. Extensions are great resources for all sorts of gardening knowledge.  You can even go through their master gardeners program.. though.. the schedules are all made for older retired folk unfortunately.  My extension:
https://extension.umd.edu/

Feed your plants after transplanting to the recommendations of your local extension and the condition of your plants.
[Spot saved for laymans guide to NPK deficiency tells]

I myself am growing Garlic, Tomatoes, Peppers, Tomatoes, Basil, Corn, Onions, Thyme, Hops, Sage, Parsley, and Savory.

Potatoes are heavy feeders (probably one of the heaviest) and one should NOT use too much nitrogen for them as it can inhibit tuber growth (will have really nice leaves though0.  Once they get into the tuber forming/growing stage phosphorus and potassium should be the main feed.  A regular feeding schedule should be maintained until harvest to 1) keep the soil from being depleted and 2) to get max yield. Amending the soil after harvest for the next year is probably still a good idea as taters can suck it dry.

Garlic is a heavy feeder but not nearly as bad as the taters.  They tend to take a good bit of nitrogen when fed so at planting use something like a mix of blood meal, guano, and feather meal with kelp and alfalfa meal to feed it through the winter and into the spring.  In spring give it another similar feeding and cut off most nitrogen once May ends.  From there a more phosphorus and potassium heavy fertilizer for bulb size up to harvest (maybe 2 feedings).  

Tomatoes will want nitrogen from planting up to June in my zone (7b) just before flowering begins.  At that point, phosphorus and potassium for flower and fruit formation.  Dont cut out nitrogen completely as many varieties of tomato will still be growing. Space your plants correctly.  It can mean the difference between a blighted and crap harvest or a big healthy one.  Keep an eye on the fruit as things like blossom end rot usually means it needs some calcium.

Corn is grass and grass likes the big ole N in NPK.  Corn is a big N feeder.  This is one of the first years Im trying to seriously grow corn and other than the nitrogen part I am a NewB with it.

Onions seem to bulb better for me when they are shallower than the instructions from the seed retailer say.  I have buried just the roots and have fed with Miracle grow of all things as it seems many have had them do well with that weird balance of NPK.  I will probably try transitioning to a P and K heavy mix once bulbing begins.  Im still trying to get my process down for that crop.

For herbs, keep them fed with a simple balanced/square fertilizer and theyll be super happy.

For Hops, clear ground and a good place for them to climb wil mean less bugs and disease for them.  They like feedings but seem to like lighter feedings at least at first from what Ive seen of my plants.

For 10/20 trays, I really do like the Bootstrap Farmer trays.  Super robust and will last a long long time unlike most of the other flimsy 10/20's.  These are a bit pricey BUT they will last:
https://www.bootstrapfarmer.com/collections/1020-trays-and-flats/products/extra-strength-seedling-propagation-tray


I use drip irrigation for my raised beds.  The company I sourced my setup from is Dripworks:
https://www.dripworks.com/


ARFCOM Garden How To's:
Waterglass' bed burn in how to:
https://www.ar15.com/forums/Outdoors/How-to-burn-a-bed-for-transplants-update-plants-are-ready-/19-696832/

Hoboninja's Mulch Thread:
https://www.ar15.com/forums/outdoors/Mulch-around-vegetables-/19-697305/

LOW50S's Bawk Bawk Thread:
https://www.ar15.com/forums/Outdoors/Official-ARFCOM-guide-to-Chickens/19-684724/

Yara Fertilizers' data and tips/tricks:
https://www.yara.co.uk/crop-nutrition/crop-solutions/

My Garden planner and fertilizer calculator spreadsheet.  Is in separate thread so improvements and such from myself and the hive here can be isolated there:
https://www.ar15.com/forums/Outdoors/Get-your-Garden-planner-and-fertilizer-calculator-constantly-changing-here-/19-698900/

Boron, mixes, and micronutrient information!:
Boron, micronutrientsm and seeding/planting mixes!

CEC: Cation Exchange Capacity:
https://www.ar15.com/forums/Outdoors/Your-CEC-or-Cation-Exchange-Capacity/19-699396/

Add your thread link to be added.




Post will be edited to add more information and sources

Cool, In the midst of building on garden beds and landscaping now.

I would only add, definitely look local to your area for info and resources.
I have always been impressed with the garden center staff,(maloney's near me and NE Nurseries), and their deep knowledge in getting you set up.

I don't think your plugging Amazon, but..... I see the reason its linked, quick reference!...which is good for some info, sometimes....and making lists....
Our local businesses could use the business a lot more than Amazon.


cheers

By all means, if you can find the stuff locally and not in the big box stores, do it.  Amazon is a good reference though for sure.  I will add the company websites for teh manufacturers of the fertilizers.

bump!

Hoboninjas Mulch thread
https://www.ar15.com/forums/outdoors/Mulch-around-vegetables-/19-697305/

Bawk Bawk
https://www.ar15.com/forums/Outdoors/Official-ARFCOM-guide-to-Chickens/19-684724/

OP updated

Yara fertilizer company with how to get more yield out of onions:
Onion yield





Everything Potato

All other crops from Yara

'gardening with Leon', 'mhpgardener', 'Armes family farms' on youtube all have great info on wicking tubs and dutch buckets, including how-to's on setup, fertilizing, etc. Leon also covers  some high tunnels and a little hydroponics, etc. some of them touch on the 'kratky method' of hydroponics. i'm using wicking tubs this year and may never plant in soil again. a good source of quality compost is a must and we're fortunate here to have several.

beware, though, it's a rabbit hole....

From a quick scan, it looks like most of their stuff can be used in the garden.  Ive created a fertilizer mixing calculator for those that like to roll their own mixes ( I have for corn, potatoes, tomatoes, and garlic).  Its actually lowered my overall cost as I can buy single ingredients and mix them for what I need.

Ive just been busy with the garden and irl responsibilities.  ...and the fucking squirrels destroyed my corn crop.

Was actually going to can most of the corn too.

I vote leave it tacked. Lots of really good info and leaving it tacked keeps it readily available. I refer to it at least once a week, usually more.

eta: moved

Given that this is a fertilizers thread, I thought it was relevant.

Its about that time.  Time to gather seed starting supplies and media.  Dont forget to look up your local extension and find the day of last frost for your area!  We will be doing quite a bit this year from turning our beds into a hoop house, hopefully expanding water gathering capability as well as a pump system for it that will change over to house water automatically.  Will also have new plants this year: Asparagus, strawberries, celery, and others.  AS usual, there will be more information coming.

The tomato crop this year for me was pretty good and we ended up with 10 pints of canned whole tomatoes + 6 pints of spaghetti sauce.  Also managed to get a gallon of jam and jelly out of the raspberry crop.

Next seasons garlic has been planted with a new variety (late italian added along side the usual music garlic) added plus a test of growing wild garlic that pops up every year.

Btw, its ok to ask about fertilizing specific plants here. Can always link to specific posts and such in the OP should it not already be in the OP.

Still waiting on teh rest of my seeds.

For those that want synthetic fertilizers, Morgan County Seeds has a large selection of both synthetic AND organic fertilizers.

Seedling Mix:
https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/G-4.pdf

Growing Mix:
https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/G-5.pdf  The hot linking function sure is fragile..lol

Boron is your friend:
https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/B-7.pdf

Micronutrients and where to get them:
https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/B-6.pdf

If deficient in certain things:
https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/B-8.pdf

More on Micronutrients:
MOAR

Guys, TEST YOUR SOIL if at all possible.

Making it a bright noticeable color might help

You can actually use the Alfalfa pellets you get from places like tractor supply for fertilizer, the meal is supposedly just the ground up pellets. 5 pounds for $23 of ground pellets at amazon vs 50lb of whole pellets for $15 at tractor supply.


https://www.youtube.com/watch?v=QtdZcwryQYg


https://www.tractorsupply.com/tsc/search/alfalfa%20pellets?

Very nice! TIL