Yes, this is for next year. I ended up selling my extra seedlings this year via facebook and that worked well. Maybe start out there and then do the market when it opens in mid-may too?
I was thinking of doing dwarf tomatoes in self-watering planters along with some flowers for sale also? I did some for family for fun this spring and they turned out very cute. I was thinking of promoting them as a gift for Mother's or Father's day?

As for what I'd like to sell.
I'm trying to focus on stuff other people don't sell but I enjoy eating or I hear about people asking for. My sister mostly sells a LOT of Okra because no one for miles grows or sells it fresh.

I grow lots of tomatoes for us so hopefully some of those. Delicata squash is hard to find in my town and people always ask about it when I post a picture on Facebook. One of the local restaurant owners overheard me talking about my garden while I was in the grocery store and asked about Chard so I'll be planting extra of that. Oriental eggplants because the ones at the grocery store are nasty, huge, and tough. Tomatillos and ground cherries, fennel, kohlrabi, french breakfast, easter egg, watermelon, and black radishes, bull's blood and chiggoia beets, rainbow carrots, brussels sprouts (maybe?), sugar snap and snow peas, french fillet beans, dragons tongue beans, mini (bush) melons, and lots of basil and mint. All of those are hard to find or very expensive even in season. The basil and mint at the store always is turning brown and not even close to freshly picked. The beans are too big and tend towards tough.
Probably dill, lavender, and cut wildflowers too. I put in lavender last year and a large wildflower border this year if they do well I'll have some for bunches and bouquets. I'm also trying to find a semi bush pumpkin that is pretty early.

You got a lot of good ideas.

Check out our local Lowe's, Home Depot, Ace hardware and landscapers to see if they will give or sell you pots. I used to sell herbs in 4" pots at the local flea market. They sold really fast.

Ask your Facebook contacts what they haven't been able to find.

And to extend your sale season, after the veggie seedlings, you can start selling ornamental perennial and biennial seedlings. Pick varieties that are native or just scarce in the local nurseries.

Dwarf plants sell well. If you google "tomato forum" it will take you to a web forum. The users on that site created several Dwarf varieties. They are far superior in flavor to any hybrid dwarf. Plus, dwarfs are usually grown by container gardeners. They get an earlier start, and will still buy plants when it is too cold and wet to plant an outdoor garden.

I've found that people want to buy tomato plants the first market day that is warm and sunny. Whether that is in March or May, that will be the day you sell the most plants. It is difficult to plan around unpredictable spring weather.

I've sold a lot of blue tomato varieties. People buy the name. They love Dancing With Smurfs.
Green when ripe varieties are almost impossible to sell plants of. Most people want a big red tomato.

Individual plants are the best money-maker. Most people don't want a six-pack of the same variety.

Most heirlooms have a story behind them. You'll want to know that story well, so you have something to talk to the customer about.

sarcastichousewife, I am a little late to this thread but since you are looking for marketing ideas for next spring maybe this will help. I sell cut flowers all summer but in the spring before they bloom, heirloom tomato plants and I had problems deciding on pot types. I did not want to spend to much on plastic pots and the cups tipped as you said, very frustrating when you have lots.

I made a compromise, I bought plug flats to start my seedlings in, this saves space under my lights, then start potting the plants up when the market opens into paper coffee cups (these are wax lined so will withstand weeks of watering). I punch a hole in the bottom for drainage. I bought those plastic trays that have a separate compartment for 2.5 inch plastic pots. These trays tightly hold the cups so they stay upright and are reusable year after year so the $2.00 per tray is not a high cost, and the cups are cheaper and deeper than the 2.5 inch pots giving lots of room for large healthy roots and a larger plant. A definite attraction to the buyer.

I take them to market in these and my plants never fall over. When I sell, I use those cardboard cup holders you see at take out places ( very cheap $9.00 for 100 or save them all winter) so customers can carry their plants easily. They really seem to appreciate these cup holders, as I cannot afford to give them plastic ones, and some get returned thru the season.

The heirlooms sell well, and I have recipe cards with descriptions of each tomato for people to read, then I can file and reuse them, but you need pictures, people love to see the final product.

So long as you do not state that you are Organic, you can tell people whatever products you are using, I always mention I do not spray and use organic supplies when I can. Biodegradable coffee cups are also a bonus.

Don't try and compete with the big box stores, you will loose. The minute they start selling a product I quit and find a new one. Your prices seem bang on, it is a fine line between charging enough and having people just walk away. Because people are buying direct from the grower ( that is you) you can charge a little less and still make a healthy profit. Know that your price point= price of seed+price of soil etc.+price of your time.

I always look out for pots, nurseries often give them away or I pick them up at the roadside. If you do a regular stall people will bring you pots too. But the used coffee cup idea is great, it is easier to transplant as you rip the cup open. What about herbs thymes rosmary ...?

Find a local landscaper. They would gladly give you pots. The most popular tomatoes when I worked in a garden center were big ones. Like Beef steaks. Cherry tomatoes were very popular and patios.

I don't know what your local stores are. If it's Walmart or Winn Dixie they don't have any say in what they sell. It's all up to the corporate offices.

zzackey, you are right, large stores have no say in what they bring in.

Are you talking large tomato or large tomato plants ? As for large plants , at our Market very few of these sell, the best sellers are the smaller ones. It seems that it is very hard to find transplants at a price where they can put in 12 or even 24 garden plants. Most of the larger ones up here are $5 to $10 a plant and it is hard to pay that price when you are putting in a garden.

Large tomatoes. I try and grow all of my veggies from seeds.

Do you have a favourite?

I have found 4" pots on Amazon for $17 a hundred. IMO having all your pots look the same gives the image of professionalism. We will be selling Flowers, tomatoes, peppers and possible cabbage and broccoli plants. we try to find seeds in larger quantities to lower cost / plant. We have found 250 seeds of a variety for very little more than the cost of a packet of 30 seeds. shop around on the internet and through catalogs for good prices. I like the idea of unit pricing $3 each 2/$5 5/$10. we sell plants with the goal of paying our farms total seed bill and cover the cost of other inputs needed on our farm for the whole season.

Save multiple pricing for if you need to sell a lot. If you have the right number that you can sell don't do hot multiple pricing. People ask for a lot of plants for pots. I do all heirlooms and pot sized plants are rare in heirlooms but I get a few varieties. I prefer the ones that are small but still indeterminate. Otherwise they produce all at once and quit. I sell Stupice and Azoychka (they rhyme). But their fruits aren't huge. People also want a lot of cherry plants. I haven't found a good heirloom red cherry. Then the rest are heirloom beefsteaks. I only sell varieties I have grown and they performed. For me that is mostly Northern Lights, KBX, Caspian Pink. I have my own bred strain of San Marzano. People want quantities of paste tomatoes but they always call them Roma.

My favorite tomato is Golden Jubilee. So sweet and has a great texture. Not one I would try to sell at the market. Most people I encountered wanted big tomatoes like Beef steaks or cherry tomatoes.