Starting Tomatoes from Seed

It’s the first week of April and seeds I planted in late February and early March are up and growing fast. I start most of my tomatoes in mid-March and early April. For some of the slower growing tomato varieties and peppers I start in late February to mid-March. At that time I started several varieties of hot and sweet peppers, two tomato varieties, and coleus. The coleus have been transplanted already and the peppers can wait another week it seems. The tomatoes (Tiny Red Currant and Black Cherokee) are in need of replanting from their cell packs to small pots. This is important so that the plants will have room for new roots and get fresh soil with plenty of nutrients for more top growth.

Seeds should be planted in a light mix of organic matter such as peat or compost made from hay and straw with some coarse sand or perlite, a volcanic glass that has been puffed with heat like popcorn. If the organic matter, whether peat or compost, is coarse then it should be sifted through some hardware cloth to break it up. I add other materials to the soil mix such as clay and rotted sod to provide nutrients. Once sifted the soil mix can be used to fill starter pots or flats. I use flats and cell packs which are rectangular plastic containers with 4 to 12 small cells for growing seedlings. Before filling them with soil I label each one with the plant variety name and date of planting on tape and written with indelible ink.

Seeds generally should be planted at depth of about twice their diameter. Some seeds like nicotiana and petunia should be barely covered or just pressed into moist soil as these need light to germinate properly. Lettuce should be barely covered for the same reason. For seeds like tomatoes, peppers, and eggplant this is about 1/8 of an inch or slightly more. To make the planting hole I take a pencil or a small stick and indent one or two shallow holes in the soil in each cell. For flats I just make a furrow with my finger. Although the cells in a cell pack are meant for one plant it is a good idea to plant two seeds if you have plenty of seeds. You can always thin later or even split the plants apart and transplant them to any cells that have no seedlings.

Once planted cover the seeds with some fine soil, put the cell packs into trays, cover with a plastic or glass sheet or a plastic cover made for seedling trays, and keep them warm. Tomatoes prefer a soil temperature of 70 to 72 degrees Farenheit while peppers and eggplant like it a little warmer. If your soil is dry add water by filling the tray with about a 1/2 inch of water. Allow it to soak in before deciding if more water is needed. You should see tomato seedlings in about 7 to 10 days. Once they are up remove the plastic covering and keep them under lights. I use 40 watt fluorescent tubes in shop lamps. These provide enough light energy to promote normal leaf and stem development. A timer keeps the lights on for 14 hours a day which is close to what the plants will be receiving once set outside in May. For heat I use heating mats designed for greenhouses with a thermostat. This has worked very well for me over the years.

After a few weeks in the cell packs or starter flats it may be time to transplant. Transplanting can be done when there are about 3 sets of true leaves and when the roots are beginning to fill up the cells in the cell pack. It is best to not let the plant become root-bound forming a dense root mass where the soil is used up. Before removing the seedlings from their flats or cell packs they should be watered. This will lessen the shock of transplant and the wet soil will hold together better during the transplant process so reducing root damage.

When transplanting you should move the plants to a pot that is about 1/2 inch wider and 1/4 deeper than the pot it came from. If the pot is larger the roots may not grow fast enough into the new soil. In the meantime the soil can become waterlogged and the seedling will not thrive.

Before filling the pots with soil they should be labeled. I prefer to write the name of the variety on one side of the pot. There is no chance of a tag or label being lost that way. Next, put a thin layer of soil in the pot. Carefully remove the seedlings from their starter flats or packs and place one plant with its root mass in each pot. If there are two plants in a cell you can separate them but I usually do that when it is time to move them up to larger pot. The plants are bigger and stronger by then and can handle a little root injury. Once the plant is in place add soil to fill in the space between the plant and the pot walls. Gently tap the pot to settle the soil and add more soil if needed.

When all the seedlings have been transplanted I put the pots into a tray filled with about an inch of water. The water will soak the soil trough the holes in the pots. If the soil is very dry I add more water once the first has been absorbed. Then it all goes back under grow lights until it is time to transplant again.

Newly transplanted seedlings in flat with water
Newly transplanted seedlings in flat with water

In the last week I have planted several more varieties of tomatoes from red to yellow types and cherry to paste. Next on the list are marigolds, petunias, nicotiana, tomatilo, basil and other herbs and many kinds of cole crops.

2 thoughts on “Starting Tomatoes from Seed

    1. Thanks! I had a crop failure too with my geranium seeds (0% germination) and my first planting of hot peppers (9 seeds out of 30). Now I’m overwhelmed with seedlings and still have the cole crops, chard, and herbs to start.


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