One of the top mistakes that beginning gardeners do in starting seeds indoors is to start them too early.
While it is very hard to show restraint when looking to starting seeds early to get the plants you’re looking to put out in your garden trying to get them started at the wrong time can result in numerous issues with the developing plants and how they will perform when transplanted into the garden.
The first thing you will need to determine when to start your seeds indoors is the date of your last expected frost.
You can find this online at sites such as https://www.plantmaps.com/climate-maps-and-data/frost .
This date will vary year to year but for starting seeds indoors it is the best starting point.
For me the date of the last frost is April 21st to April 27th .
Johny’s Seeds has an online calculator to help determine when to start seed and when to transplant them out doors. You just put in your last frost date and then look up the info in the table for the plants you are looking to grow
If you do not see the plant listed in the table or you are looking for information on the specific variety of plant you are growing then you can calculate the seed start date from the information on the packet of seeds.
You have your last frost date and the next piece of information you need is the “days to germination” for the seeds you are looking to start indoors.
This information will be on the pack of seeds. Seeds from different suppliers may have the germination in a different location but it will be there somewhere.
You will take the max number of germination days shown and then subtract that from your frost-free date.
In my case it would be 21 days from the April 30th date resulting in a date of April 9th.
But this is not the date you want to start seeds because at this point in time the seedlings have only just germinated and do not even have their true leaves formed yet.
You need to give your seedlings some time to properly form their root system and have true leaves formed to properly provide the young plants the food and energy they need to grow,
This additional time is not directly noted on the seed pack or in the catalog information. You get this by looking at the Number of days to harvest shown on the seed pack.
As seedlings grown into plants, their growth starts out slow and then quickens as they get larger and capture more resources.
As such you will want to allow ¼ of this harvest time for the young seedling’s growth prior to transplanting.
For 77 days to harvest time frame you are looking at adding 3 weeks to the growth indoors to allow the seedlings to develop enough strength to transplant and so have a good start in the garden.
This means that from the April 9th date you obtained for germination set back time you are now looking to start your seeds March 19th to allow strong young plants to form.
Starting plants too early can result in root bound plants, Leggy plants that have weak stems and generally weak plants from being grown indoor under light.