Here's a couple articles to help you:

OSU extension

UGA extension

I have to say that I don't pay attention to Days to Harvest. Sometimes it's a lot more, and sometimes it's even somewhat less. I have to assume it depends a lot on soil and climate. Also, for example, cucurbits often pop out male flowers for a long time before the females show up. How long that lasts can differ dramatically from year to year. Sometimes it goes on for a month, and sometimes it doesn't happen at all. Trying to pin DtH down to a week or two doesn't seem that sensible.

I pay attention when I'm shopping seeds, favoring fewer than greater numbers, but I don't track my planting dates vs. days to harvest.

I tend to start the majority of my seeds in pots, so days to harvest is from transplanting - also according to the links provided above.

From planting seed or transplants the days to harvest is roughly correct, I generally add +5 days if the weather has been funky. I depend upon the timing so that my summer vining crops (like melons / sweet potatoes) can take over the spring crop space as they are harvested and removed (broccoli, cabbages, beets, carrots, lettuce, peas).

vgkg same here. I plant some of my later planted corn in with my garlic. Same with vines. I find varying info. Day's to maturity. Days to harvest. I find different articles that say it is from planting and just as many that say it is from when plants emerge from soil. On top of that who knows what each seed company uses.

Because of so many variables I feel the best idea is to ask everyone else.

Normally it does not matter BUT we are getting married, at or house. I want the garden to look good in late August for the wedding. I need to estimate as best I can. My Fiancée really lover big sunflowers so trying to get some to bloom on an exact date.........

Also I do not buy transplanting starts the clock. My peppers and tomatoes go in the ground 6-8 eeks after I plan the seeds. I start getting ripe fruit from them in mid June, which is about 45 days from transplanting. Seed packets say 65-75 days to harvest. I know it sets them back some but not completely.

It's already been said but I'll say it again, days to maturity is always variable. Many factors affect when a crop is ready in your garden. From the amount of sunlight, the temperatures, the daylengths increasing or decreasing... Something planted for a fall harvest is almost always going to take longer than the same variety planted in spring. Something in part shade will take longer than if it was in full sun.

It depends on the crop as to whether the DTM is from sowing or from transplant. I use the DTM mostly to judge one variety to another in seed catalogs and websites. If two varieties sound similar but one has a 65 DTM and the other has a 90 DTM, I'm choosing the one with 65. I always check multiple sources to get a better sense of when something may be ready because the same variety can have a different DTM depending on the seed company.

Also, I've always figured days to maturity for transplants to be from a 4-6 week old seedling. Those extra couple weeks you are allowing them to grow before transplanting could account for the earlier harvest you get.

Rodney

Based on these comments, I was wondering how long it took for the actual veg/fruit to riped once developed, because getting the plants growing isn't the only consideration.

I have three different types of tomatoes and two peppers that just set fruit. I wrote the dates down and will pay attention to when they are ripe. I remember thinking that some seem to take a long time. The Shikou Eggplants and cucumbers are just flowering, so I will keep track of them too,

Rodney's comment makes a lot of sense. Use DTM for choosing between varieties, and not about calendar planning. In that sense, questions about when the time period starts are irrelevant.

I take days to maturity with a grain of salt using them only for a rough estimate when to expect to harvest at the earliest, or to decide if it's to late in the season to plant. To address the OP's question, it's at the point of planting the seed but those days to harvest are determined using optimal conditions from planting to harvest by people who know what they're doing.

Environmental factors like light, temperature, water, humidity and nutrition will affect plant growth drastically, some beyond the control of the grower. Even water PH can effect the growth of your plants if it's to high or low. So many factors come into play it would be slim anything would ever hit the "days to harvest" date right on the nuts. The only thing which ever comes close for me to "days to harvest" is sweet corn.

from when is what confuses most people. are they counting

from germination, transplant etc. .

Thanks!