When to Start Seeds

Figuring out when to start seeds can be tricky at times, especially when you’re first learning how to do it! Not all seeds should be started at the same time, and each seed has unique needs. Here, I’ll share some tips that’ll help with figuring it all out.

Is the plant variety a Tender Annual or Hardy Annual?

There are some key things you need to identify when figuring out when to start a seed. First, figuring out if the plant you want to grow is a “tender annual” or “hardy annual” will be essential for your success. A “tender annual” is just that - it’s tender. It doesn’t like to be cold, and much prefers a warm start and warmer growing conditions. If it’s too cool, the tender little seed isn’t going to want to germinate. Think about being cold in winter and just wanting to stay in and snuggle up by the fire - it’s kind of the same concept. A “hardy annual” can handle the cold, they usually prefer a cooler start and cooler growing conditions. Sometimes, it even will prefer to be sown in the fall and grow outside over winter! Tender annuals need to be sown closer to summer, and hardy annuals will be sown in late fall, later winter or very early spring. A good example of a tender annual is a zinnia, it absolutely hates the cold and wants really warm growing conditions. An example of a hardy annual is bupleurum or sweet peas, these flowers can handle cool or cold conditions.

What is your growing zone and when is your last frost date?

Your USDA Growing Zone will tell you how cold your climate can get, and based on your location your zone will tell you what the average coldest temperature is that your farm or garden may experience. Zone 1 is the coldest and Zone 13 is the warmest. This is particularly helpful to know when you’re growing perennials (aka plants that come back year-after-year from the same root system). Perennials have their limits, and if your zone is too hot or too cold for its particular liking, it won’t thrive and might not survive.

Your last frost date is not tied to your growing zone, however it may trend with zone averages. Your last frost date is the average last day your location tends to have a frost in the Spring. It’s best to figure this out by asking local gardeners, reaching out to your Master Gardener organization, looking at the past few years of weather trends, or tracking it yourself each year. Here in Bend, unfortunately, we have a threat of frost nearly year-round. But, I tend to estimate that around June 1st (15th at the latest) is when the temps are always above 32 degrees, but I do plan for an earlier “last frost” date in late-May for seed starting purposes. I watch the forecast and make a decision on when to plant out based on how things are trending.

When should you start seeds? What week is best, do you start them all at the same time?

Your seed packet will give instruction on how many weeks you should sow the seed before your last frost date. So once you’ve figured out what that date is, you can count backwards 4 weeks, 8 weeks, even 10 weeks. The date/week you land on is when you should start your seeds. Unless you have a greenhouse or hoop house that will alter the growing conditions of your seedlings to take into consideration, it’s best to trust the timing on the packet. The seed packet will take into account how slow or fast the seed will grow before it needs transplanting, and also what growing conditions it needs.