“I have a small plot and planted two tomato plants and several watermelon plants. As they grow I’m realizing my plot is quickly running out of space. Can tomato plants be trimmed back? Will watermelon plants take over my yard? How do I trim them back or space them out wide enough?” Question from George of Hagerstown, Maryland
Answer: Both plants can be pruned (please watch the video below about how to prune cherry tomatoes). Both indeterminate (vining) tomatoes and long-vined watermelons will completely take over a garden space in no time. Here are some solutions for managing these gregarious plants this summer and in the future.
Space-Saving Solutions for Tomatoes
Choose determinate, or bush tomatoes. They stay small. The only downside is that they do not produce fruit for as long as indeterminate (vining) tomatoes. If you want more fruit, you have other options.
Cage indeterminate tomatoes with tall, strong, robust cages. I recommend Titan tomato cages or any of comparable size and quality. This way, the vines will grow upright and be easier to prune.
Prune indeterminate tomatoes. Please watch the video below to learn how.
Space-Saving Solutions for Watermelon
Choose short-vine watermelons, such as ‘Cal Sweet Bush‘, a 2019 AAS award winner that has excellent melons and vines that do not take over.
Train melons on a trellis. Small-fruited types, like ‘Little Baby Flower‘, a personal favorite, are the best for trellising.
Trim back select watermelon vine branches that have outgrown their area. Keep in mind, some will need to reach a long length to properly fruit.
Watch the video below for more watermelon-growing tips.
“Lots of my tomato plants have curling upward leaves, and in most cases only edge damage. Why?” Questions from James of Greenville, South Carolina
Answer: There is a Tomato Yellow Leaf Curl Virus, but your plant lacks several of the symptoms, including stunting, yellowing, and eventual leaf browning. Tomato plants more commonly experience physiological leaf curl when subjected to various environmental stresses. In this case, I believe yours is caused by environmental stress. Here are four possible sources of stress.
Environmental Tomato Leaf Curl Causes
Too little or too much water — Vines fail to grow as well when water is lacking, and they develop root rot when there is too much water. Either can cause leaf curl. Regular, even watering will yield the best results.
High heat — Temperatures over 85 degrees F will cause most tomato plants stress and sometimes leaf curl. Some tomatoes are more heat-tolerant. Two of the best heat-tolerant varieties include the large, red-fruited ‘Heatmaster‘, which can take the high heat of the South, and disease and heat-resistant ‘Heatwave II‘, which bears deep red tomatoes with good flavor.
Wind stress — High winds cause rapid water loss from the leaves and stresses vines. Leaf curl can result.
Herbicide damage – Glyphosate herbicide damage is most common. It can cause this type of leaf appearance if a small amount reached your tomatoes from a downwind application.
“Last year my tomatoes struggled a lot. I think my soil might be tired. Should I rotate spots or should I fortify the soil? Thank you.” Question from Lucinda of Pittston, Maine
Answer: Tomatoes must be rotated on a three-year cycle for best performance, especially if they have experienced diseases. They are heavy feeders, experience lots of soil-borne diseases that can carry over in the soil from year to year, and root-knot nematodes are common pests that lower production and can live in the soil from year to year. Rotation fixes all of these problems. I recommend rotating tomatoes with soil-fortifying crops, such as peas and beans, which naturally add nitrogen to the soil. Tomatoes take up lots of nitrogen and fertilizer!
From there, I also suggest that you try short-season varieties adapted to northern climates. You can find several listed in the first article below.
“Squirrels have stolen all my tomatoes for the last 3 years. Is there any option other than putting up fencing?” Question from Barbara of Portage, Michigan
Answer: Squirrels tend to steal fruit when they are thirsty as well as hungry, and there are several proactive things that you can do to keep them away. Fences do not work due to the acrobatic nature of squirrels. Your best option is a motion-sensor repeller. There are several types. Some are in the form of hooting owls, others release ultrasonic sounds, but the best use sharp sprays of water to startle and frighten away squirrels and other pests. The Yard Enforcer is a good brand.
At my home, I also maintain a water source for birds that squirrels can also drink from and place my kitchen produce seeds–from melons, squash, etc.– outside and away from my garden for squirrels to eat. It costs no money, and well-fed and watered squirrels tend to stay away from my garden.
“How can I keep bugs and slugs from destroying my tomato fruit? They totally decimated my crop this year leaving me nothing to can for the winter months.” Question from Sylvia of Belle Plaine, Minnesota
Answer: There are several things that you can do to ensure that insects and slugs don’t damage your tomatoes. Here are six methods.
Six Ways to Stop Pests From Eating Tomatoes
Clean your vegetable beds up completely in the fall, and till lightly in the spring. This will remove any overwintering pest eggs.
In the spring, apply a layer of quality compost as a surface mulch to stop weeds and create an open, weed-free layer to keep slugs away (slugs often hide in weeds).
Use tall tomato cages, and prune your tomatoes to keep developing fruits off of the ground and away from slugs and critters.
Apply diatomaceous earth at the base of your tomato plants to deter slugs. You can also use Sluggo, a good slug killer that is approved for organic gardening.
Plant your tomatoes in the full sun (8+ hours) at least 3-4 feet apart, leaving space between plants. This will discourage slugs, which cannot withstand the sun and avoid open ground.
Apply BT spray, which is also approved for organic gardening, if tomato hornworms or other caterpillars attack your plants and fruits.
“Where can I buy Campari tomato seeds for plants?” Question from Rena of Morehead City, North Carolina
Answer: The seed for commercially available Campari tomatoes is generally difficult to find (click here for a possible source), but there are many comparable well-branched, tasty, cocktail tomatoes that taste even better. ‘Mountain Magic’ is one to try that rivals Campari. Another is one of my personal favorites, the Italian heirloom ‘Principe Borghese‘. Its large stems of delicious fruits look like those of Campari, taste great, are ideal for salads, and even make perfect sun-dried tomatoes.
From there, I encourage you to watch the video below about growing tomatoes from seed to harvest.
“I’m having trouble identifying the disease(s) that is affecting my ‘Black Krim’ tomato plant (and now may have possibly spread to the ‘Rutgers’). In late June I noticed significant leaf curl of some vines of the ‘Black Krim’. June was a dry month, so I thought it might be physiological, but watering did not seem to help. By early July, rains had returned and the leaf curl did not go away. I then started seeing healthy lower leaves turning grey-black in just days, often starting at the outside edge of the leaves. Most recently, however, I’ve starting seeing leaves covered in black spots with possibly light-grey centers (these are leaves 18-24” above ground). Petioles have similar elongated grey/black spots and some fruit stems (that produced no fruit) have turned completely black. Some leaf lesions are larger and could be the small spots merging. The main stem is not solid green and shows some grey-black coloration. There seems to be no correlation between the vines that exhibit wilt and the vines that have spots. I removed the wilted vines. Some had small dark markings on the interior of the stem while some looked healthy. So far, the fruit, which is still green, has not shown any spotting or discoloration.
The leaves do not turn yellow and brown, like you see with alternaria and septoria. Plus, it this just doesn’t look like the normal problems I get on my tomato plants every year. I’m thinking Stemphyllium or possibly TSWV (or both?), but neither seems to fit those symptoms entirely. I’ve looked at the lesions under a macroscope and no fruiting bodies of fungi are apparent. Plus, the lesions don’t have any mold-like fuzziness. The scattered small lesions and the wilting point towards TSWV, but no spotting/discoloration of the fruit is apparent (even on infected stems) and the leaf lesions don’t seem to show circular rings.
I’ve been using B. subtillus spray since transplanting, and liquid copper sulfate spray more recently. Neither seems to be having much effect. This plant was also treated with Trichoderma harzianum strain T-22 to prevent Fusarium wilt (a problem I’ve had in previous years). I realize that plants don’t all exhibit the same symptoms to the same diseases every time. It’s also possible that both diseases are at work here. Any thoughts you have here would be greatly appreciated.” Question from S Saving of Kansas City, Missouri.
Answer: Nothing is worse than experiencing debilitating tomato diseases when all a gardener wants is a successful crop. Unless a gardener plants the most disease-resistant tomato hybrids and has the most aerated raised beds and dry weather, diseases are to be anticipated–especially those of the fungal and bacterial flavor. You’re asking about at least two at once, so I will piece away at your question in an orderly fashion, starting with the photos that you shared of leaves and stems showing signs of black spotting and sootiness.
Black Spots on Tomato Leaves
When black spots like these do not cause leaves to turn yellow and die (or senesce) it usually indicates a surface mold rather than a systemic one. Your spots do not appear to be caused by grey leaf spot of tomato (Stemphylium spp.) or tomato spotted wilt virus (TSWV). Bacterial speck was another pathogen that I considered, but the small, black spots caused by this disease should have a yellow halo. The specks also do not tend to form clusters on leaves like yours.
It looks more like a light infection of sooty mold or related surface fungi. Sooty mold tends to take hold in the presence of sucking insects and the honeydew they produce. Have you observed any aphids, leafhoppers, whiteflies, mites, or the like, on your tomatoes? Even a small population can encourage sooty mold. Moreover, the fruiting bodies can be difficult to see with so little of the disease on leaves, even under a macroscope. Spraying and dry weather conditions will also discourage the development of fruiting bodies and mold spread.
Sooty mold is easily treated. Mix one teaspoon of gentle detergent to 1 gallon of warm water. Dip a clean cloth or sponge into the mixture and wipe down infected leaves and stems. The black mold should come off. Let me know if this is what you observe.
Tomato Leaf Curl
Without seeing a photo, it is difficult to determine what could have caused the significant leaf curl, wilt, and death on your tomatoes. It is certainly not tomato yellow leaf curl virus (TYLCV) because this disease causes leaves to turn yellow and contort over a longer period of time. Herbicide damage and dramatic temperature changes can cause leaf curling and fast necrosis. Herbicide damage is the most common cause. It can appear on old or new growth, depending on what tissues came in contact with an herbicide (click here to see an image of glyphosate drift on tomato.) Broad mites (Polyphagotarsonemus latus) are sucking insects that can cause leaf curl and death of tomato foliage when populations are high. The sucking insects also create honeydew, which can encourage sooty mold.
To determine whether mites are present, do the white paper test. Take a clean piece of white paper, hold it beneath the leaves, then tap the leaves onto the paper. If you have mites, lots of tiny specs will fall, and eventually, they will start crawling around. These are spider mites. Spraying the tops and bottoms of leaves with insecticidal soap and wiping them down will remove spider mites quickly. Multiple applications will be required.
Disease Resistant Tomatoes
Just for future reference, here are some tasty tomatoes with excellent disease resistance. They may not have the allure of unique heirlooms like ‘Black Krim’, but they are tough and tasty.
‘Galahad’ (F3, GLS, LB, N, TSWV): The new, 2020 All-America Selections Winner ‘Galahad’ is a big, red, slicing tomato with excellent flavor that resists five diseases!
‘Granadero’ (F2, PM, TMV, V, N, TSWV): Sauce tomato lovers should try this super disease-resistant paste tomato with uniform, red, well-flavored fruits. It is also an AAS award winner.
‘Mountain Merit‘ (F3, LB, N, TSWV, V): Lots of large, red tomatoes with good, sweet flavor are produced on this compact bush tomato.
‘Toronjina’ (F2, LM, TMV): Highly disease-resistant plants produce lots of sweet and tart, orange cherry tomatoes on shorter indeterminate vines.
‘Sakura‘ (F2, LM, TMV, N): Red cherry tomatoes are produced early and in abundance on this long-vined, highly disease-resistant tomato.
Please follow up! I would like to know if any of these potential assessments are correct. For a more definitive analysis, send some of your diseased leaves to your local extension agent. (Click here to learn more.)
“Stop my tomatoes from cracking! Last year even though the weather was optimal with sun and rain my cherry tomatoes continued to split as they grew and most were not edible as the bugs got into them as soon as they split. Is there a way to stop them from splitting like that?” Question from Sylvia of Belle Plaine, Minnesota
Answer: There are several things that you can do. Let me start by explaining what causes tomato splitting. Splitting occurs when a tomato is ripe and full of natural sugars and then it rains significantly. Tomato plants take up water fast, and due to a natural process called osmosis, the water is attracted to the plant parts with the most sugar–ripe fruits. So essentially, those sugary tomatoes fill up with too much water too fast and split. Here are the three best solutions to keep this from happening.
Ways to Stop My Tomatoes from Cracking
1. Choose crack-resistant tomato varieties. Some tomatoes either naturally resist cracking or were bred to be crack-resistant. The sweet cherry tomatoes ‘Ladybug‘ and ‘Jasper‘ are just two of many that are reliably crack resistant. You may see a crack here and there, but they are infrequent when compared to average cherries. ‘Baby Cakes’ salad tomato is tasty and both crack- and disease-resistant. And ‘Big Rainbow’ is a beautiful heirloom with great taste and crack resistance. And, if you like delicious orange slicers, ‘Chef’s Choice Orange‘ cannot be beaten for flavor and crack resistance. These are just a few of many options.
3. Pick tomatoes just before they are fully ripe. If you pick tomatoes just before they are fully ripe and allow them to ripen in a bag or on a windowsill, you can avoid the cracking problem. Slightly underripe tomatoes lack the full-sugar load that causes cracking.
For further tips on growing beautiful tomatoes, I recommend you watch our video about growing tomatoes from seed to harvest below.
Tomatoes are America’s #1 garden vegetable and growing your own from seed has its advantages. It allows you to grow the newest, coolest seed catalog varieties of your choice and helps ensure stock is disease-free at planting time.
“We have a short growing season here. I would like to get as big a head start as possible on my seedlings. I plan to start my seeds indoors but also have a pop-up greenhouse, and would like to know how early I can start seeds indoors (under lights) and then transfer to my garden before transplanting to the garden. I am interested most in times for tomatoes.” Question from Melissa of McDonough, New York
Answer: When planting tomatoes in areas with cooler, shorter summers, you need to consider the variety as well as starting/planting time. In general, it takes about six to eight weeks to yield ready-to-plant starts from seed. Using heat mats, keeping indoor conditions warm, and providing lots of light will hasten growth. Most tomatoes produce fruit between 60 to 85 days after planting, depending on the variety. Choose tomatoes that produce early and are shown to yield good-tasting fruits in cooler climates. Your average tomato colors up and gains its best flavor when days and nights are warm. You can’t count on these conditions further North, which is why the variety is important. (Click here on a full guide to growing tomatoes from seed to harvest.)
Good Tomato Varieties for Northern Gardens
‘Juliet’ (60 days, paste tomato): The award-winning’Juliet’ is a red paste or sauce tomato that also tastes great fresh. It grows quickly and will perform well for you.
These are just three of many early, cool-tolerant tomatoes you might consider.
Plant your finished tomato starts outdoors after the threat of frost has passed. Some eager tomato gardeners plant theirs earlier outdoors and protect plants with hoop covers and frost cloth. This is an option, but I find it safer to simply grow mine to a larger size indoors and then harden them off before planting. Your pop-up greenhouse sounds just perfect for the job.