Growing tomatoes is one of the most popular vegetables grown in any garden and it’s easy to see why. Nothing tastes as good as a tomato fresh from the garden!
For a successful tomato season, we asked our NGB breeder members to answer 15 of the most often asked growing tomatoes questions we receive. We hope that these answers will help you have a delicious and productive tomato season as well.
Top 15 Questions About Growing Tomatoes Answered…
1. What’s the difference between indeterminate and determinate tomatoes?
Basically, an indeterminate tomato will continue to grow vegetatively (leaves and stems) all season long, and they will also flower and produce fruit all season long. Indeterminate tomatoes typically perform best when grown in the ground rather than a container, and can get quite large/tall. Determinate tomatoes, on the other hand, will grow vegetatively to a certain point and then produce a flush of flowers, which then form fruits. Most determinate tomatoes tend to have a bush habit and can grow well in a container or in the ground. They also tend to produce a large amount of fruit over a relatively short time period (approximately 3-5 weeks depending on variety and growing conditions).
There is a third type called semi-determinate which is bushy, like a determinate, but will set and ripen fruit over a longer period of time. The 2020 AAS Award Winner ‘Celano’ is a semi-determinate. The best way to grow determinate or semi-determinate plants is to place a cage around the tomato while still small and not prune.
2. Can your tomatoes survive if you planted them too early in the season?
They might survive if you keep the young plants warm with a cloche or other protective cover. Tomatoes are not frost-hardy and will die if exposed to 32 degrees F without protection. It depends on what sort of temps you are experiencing. Tomatoes can tolerate the 40s and even high 30s F but don’t necessarily “enjoy” being grown in those temps.
3. If I have started my tomatoes from seed indoors, do I need to gradually prepare them for outdoor temperatures?
It is important to harden off any tender plants before placing them in the garden by exposing them gradually to the harsh outdoor conditions. Put young plants outside where they will receive morning sun but be protected from wind, and move them inside at night. Continue this for about a week, and then begin to leave them outside on nights when the temperature does not drop below 50 degrees F. After a week or two, the plants should be ready to transplant.
4. How do I plant my tomatoes properly?
Remove the lower leaves off of the stem and bury the stem about 2/3rds deep. The portion of the stem that is buried will form roots, which will allow more water and nutrient uptake, making the plant stronger and sturdier. Tomatoes are one of the easiest garden plants to grow. They need as much direct sunlight as possible to produce the highest yield. Native to the tropics, tomatoes require warm temperatures for good growth, so wait until the nighttime air has warmed to about 55 degrees F before transplanting them. Planting tomatoes too soon will only slow them down.
5. How often should I water my tomato plants?
Continue watering regularly for about two weeks until the plants are established. Throughout the growing season remember to water the plants deeply during dry periods for as long as they are setting fruit. Established tomato plants need at least one inch of precipitation per week.
6. I live in the middle of Florida. Everything burns up. The sun is hot during the days. What variety will handle the heat?
There are several varieties that are touted to perform well in the heat but another option is to plant early and choose an early maturing variety that will get ripe fruit before the summer heat. Often times, tomato growers in Florida will plant in late winter for a spring harvest.
7. I’d prefer not to cage my tomatoes, is there another way to support my plant?
There are lots of different ways to support your tomato. The first thing to check is whether the variety is determinate (more bush-type) or indeterminate (more of a vining, larger plant). If you get a thick stake and put it in the ground near the base of the tomato stem, you could tie up the plant along the stake as it continues to grow. Using fencing to support the plant is another option but there are also lots of attractive supports available from retailers. Another option is called the Florida Weave and works well if you are growing a number of tomato plants in a row.
8. Is there any way to prevent blossom end rot on the first tomatoes that produce? Is there one variety over another that is better preventing that?
Blossom end rot on tomatoes typically occurs when there is uneven watering, which oftentimes is out of our control depending on the amount of precipitation. My recommendation is to evenly water as best as you can. Roma tomatoes tend to show the most amount of blossom end rot and cherry tomatoes tend to show the least amount.
9. Should I fertilize during the growing season or just at the beginning?
Tomatoes need phosphorus, nitrogen, potash, and minor elements. Starting your plants off with an ample shovelful or two of compost will go a long way toward making sure the soil will provide for their needs. It will also aid the soil in holding onto moisture, which will prevent problems such as blossom-end rot. Many gardeners also add a synthetic or organic fertilizer. Some types, such as water-soluble granules or fish emulsion, can be applied when watering. There are also granular forms that can be mixed with the soil before planting or used as a side dressing, and time-release fertilizers, which can be added to the soil at planting time.
No matter what kind of fertilizer you use always follow the directions on the label. Do not over-fertilize because this will cause lush plants with little fruit set. It’s best to select a fertilizer that contains more phosphorus (P) than nitrogen (N) or potassium (K). Phosphorus promotes flowering and fruit set.
10. What causes my tomato to have lots of flowers but no tomatoes?
Often when your plants have a lot of blooms and no tomatoes it is due to the weather. When temperatures rise above 85 to 90 degrees F (depending on humidity) during the day and 75 degrees F at night, pollen will become unviable. Humidity can also come into play. In extreme humid times, pollen may become so sticky that it does not fall. On the other end of the spectrum, if it is very dry, pollen may become so dry that it does not stick to the female part of the flower. Tomatoes have perfect flowers, meaning each flower has both male and female parts and the plants can self-pollinate so pollinators are not needed for pollination.
11. How do I grow a tomato plant in a container?
For best results, select a tomato variety with a compact or determinate habit—compact cherry tomatoes are particularly good for container culture. The container needs to be deep, at least a foot, with drainage holes on the bottom. Use a sterile growing mix, keep the plants evenly watered, and place them so that they receive as much direct sunlight as possible. Feed plants regularly with a water-soluble fertilizer, keeping in mind that nutrients will leach out of the pots faster than garden soil. During periods of hot weather, full-grown plants may need to be watered daily.
12. How do I know when to harvest my tomatoes?
For the best tomato flavor, allow the fruit to fully ripen on the plant. Wait until it is deep red, yellow, or whatever final color the tomato is to be because once it is removed from the vine, the supply of sugars is cut off. To harvest, gently twist the fruit so that the stem separates from the vine. Tomatoes are best kept at room temperature and will store on a kitchen counter for several days. At the end of the season when frost is predicted, green tomatoes can be harvested and placed on a windowsill or counter. Most will gradually turn red and have some degree of tomato flavor. Placing unripe tomatoes in a paper bag will hasten the ripening process.
13. What is the best tomato to plant for home canning?
My first choice for a canning tomato would be a determinate Roma type. Determinate tomatoes produce a large amount of ripe fruit in a relatively short window of time so you would have more tomatoes to can at one time. Roma’s also are less watery, which I prefer for canning.
14. What’s the best tomato for Salsa?
While any tomato will work well in salsa, I prefer to use Roma types because they are less juicy and more “meaty”, which can mean that the salsa will not be as watery. If you want to make large batches of salsa, I recommend choosing a determinate variety because you will get a larger concentration of ripe fruit at one time. Again, though, any type can be used and fresh-from-the-garden salsa is one of my favorite things about summer.
15. Why and how do I prune my tomato plant?
The reason to prune: The goal of pruning is to create an optimal balance of vegetative growth and fruit production. Pruning can result in increased fruit size and increased earliness of the crown set. Less foliage also increases light penetration and air circulation in the lower canopy, which can reduce disease severity.
When to prune: Pruning of indeterminate tomatoes is typically done four to five weeks after transplanting. (Determinate types typically do not need to be pruned. Some say pruning makes a plant easier to work with and produces larger fruit but that is an individual choice based on specific variety and experience.) Pruning prior to the first stringing or staking simplifies the process of accessing and removing suckers.
It’s best to remove suckers when they are just two to four inches long. Removing larger suckers (thicker than a pencil) will leave large wounds that are slow to heal and can be sites for infection. Plants should be pruned when they are dry (no moisture on plant surfaces) to minimize the spread of foliar diseases.
How to prune: Prune to create one, two, or three main tomato branches through the removal of all but one or two suckers. The vines are then trained to grow on support systems. Additional suckers are removed as the vines continue to grow. Smaller suckers can be easily removed by pinching them with fingers, using a sideways, snapping motion. Larger suckers should be removed with a sharp knife or shears to prevent tearing the plant’s tissues. As the season goes on, remove all leafy suckers beneath the first fruit cluster as this prevents disease from splashing up on the lower leaves. As it gets later in the season, it’s a good idea to prune or “top” the growing tip of each main stem about four weeks before the first fall frost. This way, the plant puts its energy into ripening all remaining fruit rather than producing new fruits.
Pruning container-grown tomatoes: Container-grown tomatoes are more than likely to be a determinate or semi-determinate variety. So follow the above recommendations. There is no difference between potted tomatoes vs. in-ground tomatoes for pruning recommendations.
Bury the stem about 2/3rds deep when planting your tomato plant. This will ensure a much stronger and sturdier plant.
Still, have a question about growing tomatoes in your Victory Garden 2.0? Be sure to ask in the comments below and our NGB Member Experts will answer them for you.
Check these posts for additional tips on creating your own Victory Garden 2.0
“This post is provided as an educational/inspirational service of the National Garden Bureau and our members. Please credit and link to National Garden Bureau when using all or parts of this article.”
15 comments. Leave new
I have lots of juvenile fruit and lots of new flower and it’s almost August. I am in Coastal BC which has cooler weather. At what point should I start topping? At what point is it too late for a flowering limb to fruit? I want the plants’ energy to go into ripening what’s there as opposed to producing new fruit.
PS I am talking about tomatoe plants.
Here’s a good article from NGB Member Bonnie Plants about when to top your tomato plants so more energy goes into the remaining fruits. https://bonnieplants.com/gardening/how-to-prune-tomatoes/ (go to the “Late Season” paragraph)
I grew yellow pear, indigo blue berry , and Cherokee purple tomatoes from seeds indoors (in Portland, OR), hardened them off over a long time period, several weeks, and transplanted them when it was warm out in May, making sure to water them. They get ~7 hours of direct sun per day, and are planted in a several-inch layer of newly delivered soil mix (aged bark dust, mushroom compost, garden mulch, pumice, and sand blended together), which was laid on top of weed block fabric and last year’s soil and old hay and bark dust mulch (very little hay and bark dust) (we got lazy, we normally don’t pile on like this). The whole garden gets watered daily, with amount depending on heat. I have kale and basil and spaghetti squash doing well, but most other things in the garden seem to have their own problems. The indigo blue berry tomatoes have brown spots on their leaves, the yellow pear tomatoes next to them do not, but their leaves are yellow. The Cherokee purple tomatoes’ leaves turned blue at the tips and look burnt and dead, and have a couple of holes, and the rest of the leaves are yellow. The zucchini has white in the center of the leaves along the veins, and I have two very young transplanted cucumber who are so yellow they look neon. I recently put down a small amount of organic tomato and vegetable fertilizer, thinking that there may not be enough nitrogen in the soil, and I am no longer going to water them daily, though they were not getting so much water that the soil was soggy (~30 min of watering on cool, cloudy days to make sure what I direct-sowed doesn’t dry out, and ~1 hour on hot day mornings and another 20 min or so in the evening if I see the soil is very dry). There are soaker hoses, but those are not yet set up, so we’ve been using a sprinkler. The plants were transplanted about three weeks ago. Can you please tell me how to rescue my little tomatoes? Thank you!
Congratulations on all your efforts! Our suggestion is to take photos of each issue and contact your local extension office. Since they are local, they are the best ones to evaluate your growing conditions and issues. Next time, you might have better luck with growing the newer, more disease-resistant varieties that make it much easier to be successful. Soaker hoses are definitely preferred so as to not get water on the leaves, which can lead to disease. And water in the morning, not in the evening. Good luck!
What causes split tomatoes? When a tomato fills up with water too fast, usually after a dry spell, the skin can split. Some varieties are “crack-resistant,” which means they don’t split easily. Be sure to harvest and eat fruit with cracks right away. Left on the plant, cracks often rot or are soon discovered by bugs. Remember throughout the growing season to water the plants deeply during dry periods for as long as they are setting fruit. Established tomato plants need at least one inch of precipitation per week.
Blossom end rot is caused by a lack of available calcium in the soil for the tomato plant. Where I live in Northern Utah, our souls are highly alkaline which binds up the essential nutrients. I also work at a local nursery, and we apply calcium nitrate at planting to prevent it. Also, with the flowers and no fruit, high heat can make tomatoes drop their flowers before pollination occurs. Evenly watering doesn’t necessarily help. We use a Fertilome product called Tomato & Pepper Set to help keep the blossoms on the plant long enough to pollinate and increase your yield. We work closely with USU extension when diagnosing gardening troubles. Hopefully this can help someone! Happy Gardening!
Thank you for your comment. Yes, blossom end rot is caused by a lack of availability of calcium. The conditions that cause blossom-end rot are closely linked to inconsistent soil moisture throughout the growing season. Since calcium is only moved into the plant with an ample moisture supply, when drought occurs the fruit continues to develop but will be affected by a calcium deficiency. Rapid early growth of the plants can cause the rot because the calcium is needed by the tomatoes when they are actively growing and the plants may not be able to take up sufficient calcium quickly enough through the roots. This can occur in areas that have enough calcium in their soil due to lack of moisture. No additional calcium is required. In your area, this might be different.
For our blogs and gardening questions, we work extensively with our NGB breeder members who are at the forefront of the breeding and care of horticulture crops.
I live in the foothills of Northern California at 3,250 ft level. What type do you suggest growing. I have had success with Black Prince & Chocolate Sprinkles last year, but a lot of cracking on my Black Prince. Thanks for your pointers. Will
Please give your opinion on using crushed egg shells that have been “boiled” to prevent disease. I wish to put egg shells in the bottom of the clay pot or ground.
Jasmine, It is fine to incorporate crushed eggshells into your soil mix. Just make sure they are crushed well and incorporated into the soil well.
I need exact instructions on starting tomatoes from seeds. My seeds germinate and become seedlings. Then I put them under light and they become tall , stringy and die. What am I doing wrong? I have already started seedlings twice this season.
Thanks,
Gerri
Gerri, Sorry to hear about the seedlings dying but hopefully there is an easy fix. First off, what type of lights are you using, and how close to the seedlings are the lights? Often times, a seedling is tall and stringy because it is not getting enough light so it “reaches for it”. Many of the grow lights are low wattage and it can help a)if the lights are close to the seedlings and b)that the lights are on for 12-16 hours per day.
As for the plants dying, there is a relatively common disease called dampening off that can kill young tomato seedlings very quickly. It can typically be remedied by having better air circulation around the seedlings. If you use a plastic dome to get seeds started, I recommend removing as soon as the seeds germinate. I also find it useful to have a simple house fan turned on low around the seedlings to improve air circulation.
I can only grow in containers. My method to determine if watering is needed is to insert my finger into the soil about 1 1/2 inches. If it feels dry, I water. Is there a more reliable method? Thank you.
Janet, That is a great method! When I am asked “how do I know when to water”, my number one response is “stick your finger in the soil and see if it is moist”. In the case of tomatoes, if the plants are thirsty, they will show you by starting to droop or wilt. When this happens, make sure to water as soon as possible.