By Kathy Widenhouse, award-winning writer and owner of Tomato Dirt, a leading online source of for growing tomatoes in the home garden.
Starting tomato seeds indoors is one thing. But how can you know when to plant tomatoes outside? That’s another question altogether.
I speak from personal experience. One season our tomato planting schedule went awry. That year, spring came early – a full two weeks before our local extension’s project last frost date. Hubby was excited to plant tomatoes because he and his brothers have an ongoing challenge. Which of the three of them can pick the first tomato? This year, it would be him.
His gorgeous tomato seedlings were in the ground surrounded by luscious compost a full ten days early. And then came the rain. With it, overnight temperatures hovered in the 40s and 50s F.
Those precious seedlings fought hard. But poor drainage – plus transplant shock with a good dose of wet feet and two weeks of bone chilling cold – meant the entire crop struggled with damping off and sheer collapse.
When the ground warmed, hubby returned to the garden center with his head hung low.
And each year, when his fingers begin to itch in anticipation of planting tomatoes a bit early, I just shake my head and say, “Remember the year that you tried it.”
Knowing when to plant tomatoes is a science with a bit of art thrown in, whether you want to know when to plant tomatoes in North Carolina … when to plant tomatoes in Texas … when to plant tomatoes in UK … or when to plant tomatoes in Oregon.
Consider several factors as you decide when to plant tomato plants outside in the garden.
Check your local extension or a region map for recommended planting dates in your area. (Note that planting dates are typically 14-21 days after the last frost date, because the soil needs time to get warm.) And while you may be tempted to set your crop out once the threat of frost is past and the local experts tell you that all is safe, tomatoes do best when planted at least 10-14 days after the last planting date. You can figure out when to plant your tomatoes by using that simple rule of thumb.
For example, in our 7b zone the last frost date is March 29. The first recommended planting date is April 15. Our target date for when to plant tomatoes outside? May 1.
Make sure temperatures are consistently warm both day and night before you plant tomatoes outside. This crop doesn’t like to be cold. In addition, check the 10-day weather projections. Cold evenings or a series of rainy days are not good for newly planted tomatoes, even if you’re well past the first recommended planting date for your area.
The perfect planting day is cloudy or overcast. If you must plant when it’s bright and sunny, do it early or later in the day so that seedlings aren’t as stressed by the strong light.
The best times of day to plant tomatoes: morning or early in the evening. Conditions are the mildest then.
Are your tomato seedlings healthy and strong? The question is important whether you start tomato plants yourself, buy tomato plants from a local garden center, or purchase them through an online vendor. If leaves are yellowed, they lack nutrition. If your plants have too few leaves, they can suffer from transplant shock. If they’ve got flowers or small fruits, then cool nights may lead to blossom drop.
As you decide when to plant tomatoes, be sure to add time for hardening off to your calculations. About 7-10 days before planting tomatoes outdoors, begin setting them outside in a protected area for a few hours at the time. Increase their exposure each day to help acclimate them to temperatures, sunlight, and wind. This process, called “hardening off,” helps prepare tomato seedlings for transplanting. Gradual exposure helps your plants toughen up and reduces the possibility of injury once they’re set in the ground. With proper hardening off, they’ll have an easier transition to the garden and begin producing fruit sooner.
As you plan when to plant tomatoes in pots outside, use the same parameters as for planting tomatoes in the garden.
But you have an added factor that makes an easier decision about when to plant tomatoes in pots outside: their mobility. Containers needn’t stay in one spot. Young plants can come indoors when the forecast is for a frost, freeze, or cool temperatures.
Sure! There are at least three keys to success for planting late season tomatoes.
Know the length of your growing season
If you live in a warm climate, then you can plant tomatoes in August or later as a second crop. If you have a short growing season, then carefully consider the calendar as you …
Choose early season tomato varieties
Choose early producing varieties, smaller tomatoes, and short-season heirlooms. These types of tomato varieties set fruit and mature in the shortest time, making them easiest to grow on a limited time frame.
Choose strong seedlings
Tomatoes set out in the summer heat need strong root systems to withstand the harsh conditions. If days are particularly hot, offer the new plants shade. And be sure to place them on a regular watering schedule until they are established.
More on Planting Tomatoes
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