Choosing Tomato Varieties

How to select tomato varieties for your growing conditions

By Brenda Troutman

Tomato seedlings

Tomatoes are the number one fruit (technically speaking) grown by home gardeners and the most popular vegetable in the world. Climate change has led to more weather extremes in cold, heat (especially), drought and rain creating challenges to growing specialty crops. Environmental stressors reduce the quality of plants and their ability to set fruit. When deciding which tomato plants to grow there is an abundance of choices.  Some tomato varieties are better suited for temperature extremes then others.

Tomato plants are warm blooded and should not be planted outside until the soil temperature is above 60 degrees during the day (50 degrees night) and all danger of frost has past. Springs unpredictability and fluctuating temperatures can frustrate an over zealous gardener like myself who started tomato seeds indoors in January. These bush (determinate) or vine (indeterminate) plants do best when temperatures are between 65-85 degrees and the plants receive six or more hours of full sun daily. When temperatures drop below 65 degrees the plants will suffer, stunting plant growth and delaying fruiting. “Blossom drop” occurs when the days are warm but the nights dip below 55 degrees. The flowers fall off before being pollinated, and no fruit is set.

Pollination usually occurs between the hours of 10 AM to 2 PM. When summer temperatures reach 90 degrees during the day and do not drop much below 76 degrees at night (add in high humidity) pollen granules burst, preventing pollination. The plants go into survival mode, losing their flowers to conserve moisture.

Providing shade during the hottest part of the day, mulching to keep soil cool and moist and extra watering will help tomatoes beat the summer heat. Determinate varieties that have shorter “days to maturity” or “days to harvest” will have mature fruit before the summer heat kicks in. Once the flowers are pollinated and the fruit is set, the bulk of the tomatoes will ripen within two weeks after which the plants will start to die back.

Luckily, there are tomato varieties (hybrid and heirloom) referred to as “cold set” or “heat set” that can tolerate temperature extremes.

A partial list of varieties that will set fruit at or below 55 degrees (cold set) includes, Early Girl, Celebrity, Gold Nugget, Bush Beefsteak, New Yorker and Glacier. Many of these varieties also mature in a shorter amount of time 52-70 days making them a good choice for a late season fall planting. When temperatures do threaten to fall below 55 degrees, covering the plants with clear plastic can warm things up by as much as 20 degrees.

Just like there are cold tolerant varieties, there are tomato plants that can take the heat. Examples of hybrids are Bella Rosa, Big Beef, Florida, 4 of July, Heatwave, Homestead, and Sweet 100. Some heirloom varieties are Green Zebra, Sioux, Quarter Century and Arkansas Traveler. But even these varieties have their limits. When temps reach mid 90’s during the day and do not fall much below 80 degrees at night, production is hampered.

Choosing tomato varieties that best match your growing conditions can maximize the yield from your garden.

Seed Catalog Bounty

Things to think about when purchasing seeds.

Seed catalogs

They arrive during the coldest, shortest days of the year when gardeners are at their most optimistic (and vulnerable)…

THIS! This will be the year when the garden is perfect!  The flowers will boom profusely unmarred by powdery mildew and Japanese beetles.  The vegetable garden will be abundant (all of it, not just the zucchini) and the slugs will take themselves off leaving the seedlings whole and the cabbage unmolested. 

If it’s going to be that great, I better order some extra stuff…. 

Sigh, hope springs eternal.  Especially when looking at all those lovey, glossy pictures in seed catalogs while snow swirls outside..

I try to rein myself in, but it’s hard sometimes.  I especially have a weakness for seeds.  What harm could a few extra packs do? My only control mechanism is to force myself to plan out where I will put everything I buy.  I still end up with too much stuff, but it’s not as bad as it could be!

Seeds are a great way to grow plants, but there are a few things to think about before purchasing seeds…

  • As I said, have some idea of where you’ll plant the seedlings you intend to grow – matching the growing conditions required (amount of sun, moisture and soil type) with the spaces you have in your yard.
  • Can the seeds be directly sowed in the garden or do you need to start them in advance inside the house? Seedlings need good light to get a strong start and you may need to add supplemental lighting. With inadequate light, seedlings will be thin, leggy and weak.
  • Seedlings need your care and attention while they are growing large enough to be planted out. Do you have the space and the time to care for seedlings for 6, 8 or even 10 weeks? The seed catalog should have information on how much time a particular seedling will need. Some seed suppliers have seed starting calculators to help you plan. (You can find the last expected frost date for your area here.)
  • Consider the source of the seeds. Seeds coming from hardiness zones similar to where you live may be better adapted to your growing conditions.
  • You will need containers and a sterile growing medium to start your seeds if you are starting them indoors, plus well lit room for all those little pots.

Starting seeds can be extremely satisfying, especially when you see those lovely blooms or bite into that juicy tomato from a plant you started from a wee little seed. But a little advance thought and planning will help avoid frustration.

The Spotted Lanternfly Invasion

Spotted lanternfly on tree
Photo courtesy of Penn State Extension

The spotted lanternfly is an invasive insect that has spread throughout southeastern Pennsylvania in recent years, arriving in Delaware County in 2017.  It poses a serious threat to Pennsylvania agriculture, including the grape, tree fruit, hardwood, and nursery industries, ​and can become a significant problem pest to homeowners and residents.

Stopping the spread is a community effort, and we need your help!

The public can do a great deal to stop the spread of this invasive insect.

The extension service is asking homeowners to report sightings of spotted lanternfly to help with management and control.  There is extensive information about spotted lanternfly on the Penn Slate Extension website.  Information includes:

  • How to identify and report Spotted lanternfly
  • Signs, symptoms and potential damage
  • Management techniques for both homeowners and businesses
  • How to comply with the state Spotted Lanternfly quarantine

Informational Sessions

Penn State extension is also offering free Spotted Lanternfly Information Sessions to help inform the public about this threat. To find a session near you, visit the extension website here. Click on “Where and When” to find a session close to you.

Don’t see a meeting coming up in your community? Call your local Penn State Extension office to request a meeting.

Spotted lanternfly on apple
Spotted lanternfly on apple in Berks County, PA in October 2017. Photo: Erica Smyers, Penn State

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