Understanding When to Plant Vegetables

Don't Plant Too Early or Too Late!

June 19, 2020
Vegetables
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So, you have an idea of which vegetables you want to plant. But when should each vegetable be planted? How early can you plant tomatoes? How late can you plant pumpkins? Do you really plant potatoes on St. Patrick’s Day? This article will help you determine when to plant your vegetables in the garden.

We’re going to help you understand how to select the best days to plant your vegetables. If you find this article a little overwhelming, don’t worry about all the links to added references right away. Just read through the article first. 

Hint: If you walk away with one thing from this article, it’s the “Tools” section because we will actually calculate “When to Plant” for you! Nonetheless, it’s important to understand why we plant when we do, as it will help in the long-term.

How Do You Know When to Plant?

There are a few factors which will help us figure out when to plant which vegetables in the garden:

  1. Your Local Frost Dates: A frost date is the average date of the first or last light freeze that occurs in spring or fall. For reference, see our Frost Date Calculator for your location
  2. Your Microclimate: Keep in mind that frost dates aren’t perfect. Your property may have some “microclimates.” In other words, if you live at the base of a mountain or near a body of water, it will influence your frost dates. If your garden is next to a brick wall or on a patio that soaks up a lot of sun, this also make a difference.
  3. Your Experience: If you know you’ve always had good luck planting peas or potatoes on St. Patrick’s Day and tomatoes on Mother’s Day, stick with what works for you!

Of course, we need to remember that nature is unpredictable. There’s always a chance that a sudden frost can hit our garden at an inopportune time. However, we can also protect our garden from frost.

Tools to Determine Planting Dates

To help you plan the best dates for planting vegetables, herbs, and fruit, we have two excellent tools:

  1. Planting Dates Calendar: Our free planting calendar already calculates the frost dates for every vegetables in one easy tool, customized to your zip code. It will tell you the best time to start seeds indoors and outdoors, as well as when to plant young plants outside. Click here for the Almanac Planting Calendar.
  2. The Garden Planner: We have an even more comprehensive planning tool that tells you not only first planting dates based on the frosts, but also the full range of planting, growing, and harvesting dates. This tool has an annual fee, but you can try it for 7 days for a free trial, which is ample time to plan out your first garden! Click here for the Almanac Garden Planner. 

Spring Planting Considerations

In the early spring, we plant cool-season vegetables. The biggest issue in spring is the soil temperature, since we’re directly following winter, when the ground may have been frozen. As most regions experience some sort of frost, the soil needs to warm enough for seeds to germinate. And it can’t be too wet, either, or seeds will rot.

Soil Temperature

While frost dates are a general guideline and fine for beginners, knowing your soil temperature is an even more accurate factor to rely on. Frost dates are based on historical averages and predictions, so they can vary quite a bit from year to year. Soil temperature readings, on the other hand, are cold, hard numbers!

However, to determine the soil temperature in your garden, you need to buy a soil thermometer. They are not expensive. You simply insert the thermometer a couple inches in your soil for a few days in a row to get a reading. Go slightly deeper if you are planting transplants instead of seeds. See minimum soil temperatures for germination.

Spring-Planted Crops

Some spring-planted crops mature quite quickly and others more slowly, so it’s important to know the maturity dates from you seed packet to understand how to schedule your plantings.

  • Plant cool-season veggies that maturity quickly (lettuce, spinach, leafy greens) and are also harvested in spring.
  • Plant cool-season crops that mature in early summer (peas, broccoli, cabbage, and others)
  • Stagger any crops that have a very short harvest period (peas, radishes, turnips). For example, many radishes mature in 21 days or so, and you want to harvest them when they’re mature or their taste becomes woody. So, instead of planting all your radish seeds at once and being forced to harvest them all at once, stagger plantings 7 to 14 days apart. 

Of course, you can start seeds indoors in late winter to get a head start on spring. This is helpful for people who live in the far north and have a short growing season. It may be advanced for some beginners but see our advice on starting seeds indoors and which vegetables are best if you’re interested.

Summer Planting Considerations

The “warm-season” crops cannot be planted until the soil has warmed up enough, which generally doesn’t happen until late spring or early summer, depending on your climate. Crops such as peppers, melons, and tomatoes need a higher soil temperature and are very susceptible to frost. If you plant too early in cold spring soil, the seeds will not germinate or be of poor quality. Transplants will also grow very slowly.

Here at the Almanac, there’s a piece of folk wisdom that says that all plants in summer—no matter when they were set in the ground—will catch up by the end of July. In other words, faster growth during warm weather will even allow late plantings to catch up with early plantings made before the soil was warm enough.

Again, note the maturity dates listed on the seed packets as you plan your planting schedule.

  • Some warm-season crops have short harvest periods, such as bush beans and sweet corn. Many warm-season crops with short harvest periods can be planted successively throughout the early summer season, which will extend the harvesting period.
  • Other warm-weather veggies such as squash, tomatoes, and pole beans will produce for a longer period of time, so you typically only need one planting.

Fall Planting Considerations

We call this “fall planting” because the crops mature in the fall, but they actually get planted in mid- to late summer. Not all beginners will do a fall planting, but there are indeed some big advantages for some gardeners to extend the season. First, the ground is already warm! It’s much easier to start plants. Second, there are fewer bugs and pests. Try to extend your season for maximum harvest!

  • Mid-summer is a good time to plant warm-season crops with a short harvest period (bush beans, corn).
  • Also in mid-summer, you can plant autumn veggies that mature slowly (parsnips, rutabagas, brussels sprouts, and others)
  • In late-summer, as the weather cools a little, plant vegetables that mature quickly (lettuce, radish, others). 

The challenge, of course, is that you can’t wait too long to get your fall crops started. If you do, all your hard work could be curtailed by an early fall frost.

How to Calculate Your Last Planting Date

  1. First, determine the average date of your first fall frost. (See our Frost Dates Calculator here.)
  2. Then, look at your seed packets, which should tell you how long each plant will take to mature, and back out those days from the fall frost date. 
  3. Then, back out another 10 to 14 days to allow for harvesting.
  4. Finally, because fall days are cooler ad shorter with less direct sunlight, we need to add a “fall factor” and back out an extra 7 to 10 days.

For example: The days to maturity for Black Seeded Simpson lettuce is 45 days. Add 14 more days for harvesting, and then add 7 more days for a ″fall factor.” This means a total of 66 days. If your fall frost is around November 1, you’d need to back this out by 66 days and plant your seeds by August 26. If you plan to offer your plants protection, you can plant 2 to 3 weeks later and still expect to get a good harvest.

We have a handy fall garden guide with last planting dates for popular crops here

Also, here is some advice on which vegetables to plant in the fall

  • Before the first fall frost, you’ll need to harvest those warm-weason vegetables: pumpkins, winter squash, tomatoes, melons, peppers, beans.
  • However, there are cool-season vegetables that can stay in the ground after frost but before the ground freezes as long as you much the ground: turnips, rutabags, winter radishes.
  • Also, there are some veggies that can stay in the ground until the temperature dips below freezing: cabbage, Brussels sprouts, collard and kale, kohlrabi, chard, spinach.
  • Garlic is also planted in the fall, for harvesting next summer! See our Garlic Growing Guide.

To learn more about the individual vegetables, herbs, and fruit that you want to plant, visit our complete Growing Guide Library.

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