The answer to what month to start seeds indoors depends on your local last frost date. Most gardeners begin between February and April. Your exact seed starting month changes based on your growing zone and the crops you want to plant this season.
I learned this lesson during my third year of gardening when I started tomatoes in February for my Zone 6 garden. Those plants grew tall and leggy by the time transplant weather arrived in May. The next year I waited until mid-March and my seedlings came out stocky and strong. They thrived after going outside and produced fruit earlier than my neighbors who bought nursery transplants.
The calculation method works like this: find your last frost date and count backwards using each crop's lead time. Tomatoes need 6 to 8 weeks of indoor growing before transplant. Peppers require 8 to 10 weeks because they grow slower. Broccoli and cabbage need just 4 to 6 weeks since they handle cold better than warm-season crops.
Your growing zone changes the best month for starting seeds by several weeks or even months. Zone 5 gardeners with a May 15th last frost date start tomatoes around March 15th. Zone 8 gardeners with a March 15th last frost can begin those same tomatoes in late January or early February. Zone 3 gardeners might wait until April because their frost-free date comes in late May or early June.
You can find your local frost dates through NOAA climate data or your state's cooperative extension service. Type your zip code into their frost date calculator. You get both average last spring frost and first fall frost dates. These numbers form the foundation of your entire planting calendar for the season ahead.
Create a simple spreadsheet listing each crop you want to grow alongside its indoor growing time. Start with your last frost date at the top and work backwards. Mark each seed starting month on a wall calendar or phone reminder so you don't miss your window. This planning takes 30 minutes once and saves you from rushed or mistimed planting all season long.
Some crops have flexible timing while others demand precision. Lettuce and herbs forgive starting a week or two early or late. Peppers and eggplant punish poor timing with stunted growth or failed transplants. Check university extension guides for your crops. They give tested tips based on research rather than guesswork from random websites.
Read the full article: When to Start Seeds Indoors: Ultimate Guide
