The Stanislaus Sprout
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When to Start Seeds Indoors

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In order to determine when to start your spring/summer vegetables indoors, you need to know your estimated last frost date. The following link from UC Davis gives a chart showing estimated last and first frost dates for areas in California. California Gardening ~ https://cagardenweb.ucanr.edu/~ Vegetables |When should I plant my garden? | Frost dates   Subject: Approximate First and Last Frost Dates in California

This indicates only a 10% probability of frost in the Modesto Area by March 3rd. So, lets adjust our start times based on transplanting your starts outside on or after March 3rd.

You just need to back date from March 3rd the number of weeks suggested on your seed packets.

Racks of seedling trays with a light.
A grow light set up, Tim Long.

A few more popular vegetables would be started as follows:

Vegetable                    weeks before last frost            earliest start date

Peppers:                     8-10 weeks before                  January 3rd

Tomatoes:                   6-10 weeks before                  January 21st

Cucumbers                  3 weeks before                        February 11th

Summer Squash          3 weeks before                        February 11th

Author sitting outside on a bench with seedlings.
Author repots his plants for hardening off, photo by Jennifer Long.

One last important detail. You need to “harden off” your starts before planting in the garden. This means taking about a week to adjust them to outdoor conditions. Move them out the first day for a couple of hours and then back inside to your starting area. Continue this each day while increasing the length of time outdoors and the amount of direct sun they get before transplanting.

Lots of good information is located on the seed packet that lists start times, depths, light, water and other needs.

The UC Master Gardeners of Stanislaus County are offering a spring vegetable class at the various libraries in February. See our Web page at https://ucanr.edu/sites/stancountymg/Calendar/  for times and locations.

Tim Long has been a UC Master Gardener in Stanislaus County since 2020.

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Coming Soon: an in-depth article on how to start peppers, one of the most challenging vegetables to start from seed.