Answers to your tomato questions from the experts at the National Garden Bureau.
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 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. Indeterminate tomatoes will need a larger cage.
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 ˚F (0˚C) without protection. It depends on what sort of temps you are experiencing. Tomatoes can tolerate temperatures down to near freezing, but their growth can be seriously hampered and fruiting delayed if they even suffer temperatures below 50˚C (10˚C), especially if the cold lasts more than a few hours.
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 55˚C (13˚C). After a week or two, the plants should be ready to transplant.
4. How do I plant my tomatoes properly?
Remove the lower leaves from the stem and bury the stem about two-thirds 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˚F (13˚C) 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 1 inch (2.5 cm) of precipitation per week.
6. Which growing method gives the largest tomato harvest?
Growing tomatoes in a tomato cage has been shown over and over again to produce the largest crop of tomatoes with the least amount of effort. With caging, no pruning is required (the so-called suckers some gardeners remove are actually fruiting stems!) and, since pruning spreads diseases, plants are generally healthier. The technique is simple enough: just set the cage solidly over the plant at transplanting time. There is more information on caging tomatoes at How to Cage Your Tomatoes.
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 can often be out of our control depending on the amount of precipitation. The recommendation is to evenly water as well 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 on to 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.
10. What causes catfacing on my tomatoes?
Catfacing, caused by incomplete pollination in cold weather, is a malformation of the fruit, usually on the blossom end, and is more common in larger tomatoes such as beefsteaks. To prevent this disorder, choose from among the many varieties that are resistant.
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 (30 cm), 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?
The best canning tomato is 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. Romas also have a less watery texture, preferable in canning.
14. What’s the best tomato for salsa?
While any tomato will work well in salsa, again Roma types are preferable, 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, choose a determinate variety, because you will get a larger concentration of ripe fruit at one time.
15. What are the benefits of growing tomatoes?
Tomatoes provide abundant vitamins and minerals. One cup of cherry tomatoes will provide 25% of daily recommended Vitamin A, 32% of Vitamin C, and a substantial amount of Vitamin K and potassium. Tomatoes are also an excellent source of lycopene, a powerful antioxidant that has been linked to a reduced risk of cancers.
For the best tasting, most nutritious tomatoes, grow your own and eat them fresh from your own Victory Garden 2.0.