Starting Tomato, Pepper Seeds Indoors

Every summer, I make the same promise to myself: "Next year, fewer tomato and pepper plants!" And every winter around this time, I try to start small. But somehow, things get out of control...

Late January and early February is the ideal time here in Northern California for starting tomato and pepper seeds indoors. And while you're at it, why not start a few others, such as more cool season leaf crops and summer annual flowers from seed. Those leaf crops (lettuce, spinach, chard) can be transplanted outdoors after about three weeks worth of growth indoors (take a few days to gradually introduce them to the outdoors, perhaps bringing them and their containers back in at night).

Those tomato and pepper plants, along with the summer flowers you started from seed? Keep them protected, indoors, until mid-April. Then, gradually acclimate them to the outdoors as well.

The main problem with outdoor planting of tomato and pepper plants this time of year? Soil temperature. Those summer vegetables do not start actively growing until soil temps reach the mid-60's, and don't really take off with food production until soil temperatures are above 70. Right now? Soil temperatures are hovering around 50 degrees here in the Sacramento area.

Another good reason to delay outdoor planting of those young vegetables until late April-early May: the wind. March is a very windy month in the Central Valley, with northerly winds hitting 20-30 miles per hour, for several days.

What you need to start your seeds:

• A sunny, indoor window or greenhouse.

• Small pots or flats with good drainage. Clean thoroughly.

• An easy draining, pathogen-free soil mix, preferably soilless.

• No greenhouse? Use good quality light fixtures.

• Air movement.

• Small amounts of fertilizer.

• Seed heating mat (optional).

If you are starting your seeds indoors, you would benefit from an extra lighting system, such as fluorescent bulbs hung a few inches above the plants. If the light source is too far away, the plants will get leggy.

I like to use 3"- 4" azalea pots for starting seeds of tomatoes and peppers. I will plant three or four seeds per pot. When they come up and put on two sets of leaves (about three weeks after germination), I'll transplant them to their own pot.

(NOTE: this is how a small number of plants becomes wayyyyy too many, in a hurry!).

Those old six packs and partitioned flats are ideal for starting green, leafy crops. Thin out the seedlings so that there is only one remaining in each cell.

The real key to seed starting success? The soil. More exactly, the soilless mix. Using soil from your garden to start seeds is filled with threats to seed survival: competition from weed seeds, soil-borne diseases, and too heavy a soil. Damping off, a common malady of new seedlings, is due to cool, wet, heavy soil, a perfect environment for pathogens, especially pythium.

Using a soilless mix to start seeds helps avoid introduction of those pathogens. You can purchase bags of "Seed Starting Mix" at your favorite nursery. 


Or, make your own. The recipe I use:

4 parts well aged compost

2 parts peat moss or coir (be sure to thoroughly moisten the peat moss first)

1 part perlite (aids drainage)

If you are worried that the mix you are using is too heavy, you can help your seeds get off to a good start with bottom heat, via a seed heating mat. These are especially useful for germinating pepper seeds, which need higher temperatures to germinate.

Put the seed starting mix in each pot or flat, and then thoroughly soak it. Although it isn't necessary for starting seeds, you can add a diluted liquid fertilizer at this time. I tend to use fish emulsion (5-1-1 NPK) and a sea kelp product, which promotes root production. Generally, there is no need to fertilize until the seed has produced two sets of true leaves. 

"True Leaves" look like the finished product. The first two leaves that emerge from a seed are usually oval shaped cotyledons, which are embryonic leaves.

The seeds are planted just below the soil surface in each pot, no more than a half inch deep.

Once the seeds are up and growing, introduce some air movement into the room, such as a house fan. This helps the new plants avoid diseases. And, air movement can help strengthen tomato stems, according to Debbie Flower, professor of horticulture at American River College, where they use fans in their greenhouses, for up to 16 hours a day.

Coming in March: those containers of tomato and pepper starts will easily become many more containers of tomato and pepper plants, after separating out the three or four starts per container.

Yep, another year of too much.