​“When should I plant my tomatoes?” A common answer in central Iowa is “any time after Mother’s Day”. Depending on the year, Mother’s Day in the U.S. can be as early as May 8th or as late as May 14th.  While that date lines up well with when our chance of another 32 F frost nears zero (see the risk of frost chart below for Ankeny, Iowa), does that rule of thumb apply everywhere every year?  


The best planting time for tomatoes depends on your weather conditions, but here are a few guidelines that can help you decide when to plant regardless of where you live.

​The first thing to understand about planting tomatoes (and peppers, eggplants, melons, and squash) is that they are warm weather plants. Tomatoes will not grow in temperatures below 50 F. The first sign that it is warm enough to plant is the night time temperature stays consistently above 50 F.  The ten-day weather forecast for my town in central Iowa indicates only 2 of 10 days in the forecast will reach that minimum requirement which means I will wait another week or more to consider planting warm season crops.

The second thing to consider is the temperature of the soil about 4" deep. Ideally, tomatoes should be planted when the soil temperature is at least 60 F in the early morning. You can use a soil thermometer, a kitchen thermometer, or just stick your finger in the soil for a minute and see if it feels cold (if it feels uncomfortably cold it is probably below 60 F). So far this year, the reported soil temperatures have only reached about 50 F.  Raised beds or a garden with a good southern exposure could be warmer than the reported temperatures.    

If you are like us, tomatoes are not the only type of plant you like to grow.  We also grow peppers, eggplant, squash, and melons.  Add 10 degrees to all of the tomato temperatures above when deciding when to plant peppers, eggplant, squash, and melons.  Cool season plants like peas, potatoes, onions, celery, kale, carrots, broccoli, and cabbage can be planted now if not already done.
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If you haven’t purchased flower seeds, tomato, pepper, eggplant, greens, potatoes, onions, strawberries, herbs, or squash plants yet, check out our plant sale page at https://www.iowabackyardfarmer.org/springplantsale.html

I visited with some friends and fellow gardeners recently and discovered we all love to try new tomato varieties, but we pick them for very different reasons.  Some pick based on the story behind the variety.  Some look up reviews and get recommendations from other gardeners.  Some choose a variety based on its flavor, looks, or the pattern of its leaves.  Some pick a variety based on what they plan to use it for - canning, slicing, snacking, roasting or stuffing.  We grow about 50 varieties every year, and it is just a drop in the bucket compared to the number of varieties available.  So how do I choose from so many?  

We grow several heirlooms and I love all of their flavor and personality. But what does it mean when someone says heirloom?  In a general sense an heirloom is something of value that is passed down from generation to generation.  Many heirloom varieties have great stories attached to them for this reason.  An heirloom plant is open-pollinated and grows true to type which means that if you save seeds from an heirloom plant you can plant those seeds and get the same type of plant again.  If it grows true to type for several generations then it is an heirloom variety.  If you want to save seeds, make sure that you pick an heirloom tomato to plant. 

So, why doesn't everyone grow heirloom tomatoes?  Everyone used to until breeders developed hybrid tomatoes. Hybrids have advantages that heirlooms don't.  Hybrids are more uniform from plant to plant, generally have better yields, are less prone to cracking and splitting, and have better disease resistance.  Commercial growers use hybrids so they can time their tomato harvests which allows them to efficiently harvest their tomatoes.  We notice that most hybrids yield earlier than comparable heirlooms which means you can have a larger harvest.  Some hybrids store longer and have a more consistent tomato size which makes them more marketable and easier to manage when processing.  All of those things sound great too, so why don't we all grow hybrids? 

Some people think hybrid means GMO, but it doesn't.  You can buy organic hybrid seed just like you can buy organic heirloom seeds.  Tomatoes are self pollinated and don't readily cross-pollinate with other varieties.  Hybrids just means that someone selected one variety to be the female parent and another variety to be the male (pollen) parent of the seed you are growing.  You could do that yourself if you wanted and make a whole new variety and name it yourself.  The crossing between two different varieties, sometimes makes a super kid and those plants are worth planting. 

We grow lots of hybrids.  I love the consistent performance and disease resistance. The issue with hybrids is that if you save seeds from those tomatoes and plant them next spring, you won't get the same plant.  If you want to get the same plant, you have to buy seeds again.  Some newer hybrids are great as breeders are making plants that combine some of the classic heirloom flavors with the increased disease resistance and consistent performance of a hybrid.  One example I grow is called Brandy Boy.  It is a cross between Brandywine  (super flavor but little disease resistance) and Better Boy (better yield and disease resistance). Brandy Boy has the best qualities of both parents - very flavorful with an earlier and higher yield.  

My advice?  Heirlooms are great if you will spend a little more time to make sure you take excellent care of them. They have great flavor and fun personalities.  They come with great stories and history, and some of them are very tasty. They can be more difficult to grow and they aren't always consistent in their yield.  If you have diseases, or you want a bumper crop of tomatoes that are uniform for preserving or can't spend much time maintaining a garden, pick a hybrid.  There are lots of great choices out there!

Can I tell you a story?  I didn't used to pay attention to the differences between determinate and indeterminate until I started vertical gardening with the T-frames we use now.  Some years ago, I had started my seeds indoors and they were beautiful.  Steven was watching YouTube videos on how to increase yields from our garden and found the Mittleider vertical gardening system.  He thought we should try it so he built a T-frame and set it up in the garden.  I planted all my beautiful seedlings, and then I read the details. 

Determinate tomatoes:

1.  Are predisposed by their genetics to grow a certain height and set a certain amount of fruit. 
2. Usually fruit earlier in the season and for a shorter amount of time. This can be perfect for canning, when you want a lot of tomatoes all at once.
3. Tend to grow bushy and are shorter that indeterminate tomatoes.  
4. Work well if you don't want to stake tomatoes, or make big cages.

However, determinate varieties are not ideal for growing pruned to a single stem up a trellis.  For that we needed an indeterminate variety, so we ran to some stores to see what we could find.  I replaced all my determinate tomatoes for a grab bag of indeterminate plants. Lots of these turned out to be heirlooms that I loved.

Indeterminate tomatoes:

1.  Are not limited to a certain height or yield by genetics. They keep growing as long as the conditions are favorable.  Mine can grow 12 feet tall in our garden, and I have seen them 30 feet tall in hydroponic greenhouses. 
2.  Need a larger space and a trellis or tomato cage to keep them off the ground. 
3.  Would have a hard time in a patio pot since they grow so tall.

Many tomato varieties are indeterminate which provide tomatoes until the plant is killed by disease or frost.  We list which variety is which on our spring plant sale page, or a quick search online can help you figure out whether your favorite tomato is determinate or indeterminate.

​​This is the fun part, and there are so many options! Tomatoes are edible art.  I have grown red, purple, green, black, pink, yellow, orange, and stripes.  The color doesn't guarantee the flavor, but it is an indicator.  I find that:
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1.  Red tomatoes have a classic tomato flavor, sweet and acidic.  The redder the tomato, the more acidic it tends to be.  
2.  Pink tomatoes tend to be a little milder than red. 
3.  Yellow and orange tomatoes tend to be even sweeter and less acidic than pink and red tomatoes.
4.  Purple/black tomatoes have a earthy smoky flavor. 
5.  Green tomatoes tend to be sweet with a little zing.  

As far as shape goes, ox heart tomatoes don't have many seeds but are still great to eat fresh and I love them for canning.  An elongated shape is classic for paste tomatoes.  They tend to be a little drier, which is great for sauce.  Big round beefsteaks are going to be juicy.  Cherry tomatoes have a higher skin to inside ratio, which is not ideal for saucing as they have more seeds and skin to flesh, but smaller varieties can be great for making sun-dried tomatoes or holding their shape in salads, pastas and snacks.

When people ask me what kind of tomato they should plant, the first question I ask is "what are you planning to use it for?"  If you can hundreds of quarts of tomatoes and sauce like I do each year, then you will want tomatoes that promises a large yield and uniform fruit.  I love the heirloom lumpy rippled look, but it is a real pain when I am trying to peel hundreds of them.  I also love a great big juicy beefsteak tomato, but if you are making spaghetti sauce, all that watery juice and seeds in your sauce might not be what you want.  A good paste or ox-heart tomato will be much thicker and less seedy.  If you love a fresh sliced tomato, a paste tomato will be too dry, and if you are wanting to roast tomatoes for soup, remember that those black and purple tomatoes that are amazing freshly sliced, will make your sauce look an unappetizing brown when they are blended together.  Keep the end use in mind when planning what to plant and you will be much happier.

Last on the list, but one of the first things to consider is what kind of space you will be growing in.  We covered indeterminate and determinate above. Remember that you will need a trellis or large tomato cage for an indeterminate tomato, but they can be pruned to grow up and not out.  Determinate tomatoes should not be pruned the same way, and they will be bushy. 

Don't forget to consider sunlight requirements.   If you have a shady backyard with only 3-4 hours of direct sunlight plant a smaller fruiting tomato like a cherry or grape tomato.  If you want to plant cocktail tomatoes, make sure you have at least 4-5 hours of sunlight.  Slicer tomatoes require 6-7 hours, and beaksteaks require at least 7 hours of sunlight to get maximum production.   Don't worry if your garden spot only receives a few hours of direct sunlight as there are many varieties of various shapes and colors that will produce very well with just a few hours of direct sunlight.  If your garden gets 7 or more hours of direct sunlight then you've won the "tomato jackpot" as you can grow any size of tomatoes you want and they should produce well.

My last advice is if you have the space try a few different varieties.  You will sort out pretty quickly which ones work well for you and if you get a bumper crop you can always share it with your neighbors.  The nice thing about gardens is that there is always next season to try again!