Seed Starting Time is Here by Lee Miller

Correction: In last week’s column, the date of the Master Gardener Smart Gardener Conference was listed as March 8, whereas the date should have been listed as Saturday, March 3. For more information see the San Joaquin Master Gardener website.

Why start plants from seeds? It is fun and challenging for one reason. You also have more choices which can also be a learning experience, (one online tomato catalog lists more than 600 varieties—so many seeds to try and so little time!). You can save money as seeds are cheaper than buying plants and one seed package may last a few years and produce lots of plants.

Now is the time of year to think about tomato, pepper and eggplant seeds going into the seed starting pots or whatever you use to start seeds. Also time be planting parsley, basil, thyme and other herbs and flowers too. The best way to do this is using a heated tray or heat mat to provide about 70+ º F soil that is about right for germination. In February, the day length is too short to provide sufficient light, so I put the light on a timer to provide 14 hours of artificial light using fluorescent lights. The light should be kept within 3 inches of the plants as they grow. This will result in robust healthy plants. If you start your seeds on a southern exposure windowsill you can grow plants, but they will likely be scrawny as they reach for light this time of year.

Getting the right soil for seed starting is important. I have used some commercial seed starting materials and found them lacking in fertility which requires adding fertilizer as the plants grow. It is important to use a seed starting medium and not potting soil which works best for container plants, but not for seed starting. I have used screened fine compost that I have produced for seed starting and have had excellent results with it. Compost will feed the plant until planting time without the need to add a fertilizer. I have never sterilized the seed starting medium as some recommend and have not had any serious problems with damping off fungus which attacks plants just above the roots. Part of the reason for this may be keeping soil temperatures warm and definitely not overwatering.

You can make your own soil mix and I am always tempted to experiment, but using pure compost has worked for me for so many years, so I don’t try something different. However, here a mix recommended by University of Michigan Extension: “Mix one-third part sphagnum peat moss or coconut coir fiber with one-third part finely screened compost and one-third part vermiculite and add about 1 to 2 cups of worm compost to a 5 gallon bucket of this soil mix.” The vermiculite will help hold water as does the compost. The worm compost is a good nutrient source.

Whatever the soil mix used, it is important to have a deep soil mix because you are growing roots that will support the plant after transplanting. I usually start my plants in half gallon cardboard cartons that milk and fruit juice come in. I save them all year and then cut out one side and punch holes near the bottom for drainage. This provides a 4 inch deep rooting zone for healthy root growth. I transplant from these containers to 4 or 6 inch deep pots to ready them for sale or transplanting to the garden. A lot of commercial kinds of materials are available for seed starting.

After transplanting you can put the plants outside during daytime in March and bring them in at night if frost threatens. In most years, you can get by without frost in March, but it is good to pay attention to the weather reports, just in case and move them inside if frost threatens. Being outside will toughen up your plants and ready them for planting in the garden.

Garden Reminders: If you haven’t pruned your roses or fruit trees do it now and that goes for perennials like sages and Artemisia too. Also time to plant any artichokes, asparagus and strawberries or other bare root plants. Valentine’s Day is about the last chance to spray peaches and nectarines for peach leaf curl, a fungus that can cause all your new leaves to be deformed and drop off. It can affect young green shoots as well. Spray all sides of branches and trunk where the fungal spores may lurk to infect the buds. Available fungal fixed copper spray products contain a copper metallic equivalent rating on the label and the higher this number the more effective the product. It is advisable to add a tablespoon or two of horticultural oil to the spray to help make it stick better and provide better protection. Happy Gardening.


If you have a gardening related question, you can contact the UC Master Gardeners at 209-953-6112. More information can be found at:


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  • Blog Author

    Marcy Sousa

    Marcy Sousa is the San Joaquin County UC Master Gardener Program Coordinator. She is a Stockton native and enjoys teaching others about gardening. She has her bachelors from Stanislaus State in Permaculture. She has been with the program since 2007. Read Full
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