This time of year is one of abundance in the garden. Nothing illustrates this better than the huge, red tomatoes weighing down the tomato plants.
At Green Venture, we have celebrated our tomatoes in several ways thus far this year: selling tomato seedlings at our seedling sale this spring, potting up donated plants into containers to redistribute to our community partners this summer, and now, sharing all of our tomato knowledge with our Grow a Row participants and a special group of gardeners we have been collaborating with this season.
Earlier in the summer, the Immigrants Working Centre (IWC) reached out to us to see if we would collaborate on some Zoom garden workshops for a newcomer women’s gardening group they started this spring. We’ve talked about what garden resources are available and unique in Hamilton, the benefits of gardening and garden safety, weeds (how to manage and what ones you can eat!), and this week we will talk about tomato care.
Here are some of our tips for caring for your tomato plants to ensure you a bountiful harvest and lots of future cans of tomato sauce!
Pruning is the first step in tomato care. However, you must first ask: is your tomato plant indeterminate (vining) or determinate (bush)? Determinate varieties do not need pruning except for removing a few leaves for air circulation or ones that have died or are showing disease.
If you have an indeterminate plant, you will want to start pruning as soon as your plant is trellised and has multiple sets of leaves. You can find out what your plant is by searching the variety online.
We prune in order to: direct plant energy, increase air flow (preventing disease), and to ripen fruit.
The following diagram from the University of Wisconsin-Madison Extension Service is a helpful illustration of what to prune:
- Remove bottom leaves to increase air circulation, expose fruit (to speed ripening), and to prevent disease spread (remembering to leave at least 3 sets of leaves at top).
- Clip out suckers so energy is directed into the main stem and flowers and to keep the plant from becoming too dense and unwieldy.
- Lastly, towards the season’s end in late September, consider cutting off the top main leader of the plant. This is a farmer tip to force the plant to ripen early (vs lots of green fruit) by inhibiting more vertical growth.
Last important details:
Use clean pruners and clean between plants or rows, particularly if there are signs of disease. Alcohol spray is best (another use for that hand sanitizer!)
Prune on dry days and when there’s not rain in the forecast (more challenging this year but try your best!).
Tomatoes are vines that love nothing more than to ramble through the garden. We trellis in order to conserve space, make harvesting easier and to prevent disease by raising the plant off the ground to prevent soil splashing on the plant during rainstorms (a source of fungal based disease).
If you have only a few plants, a tomato cage or a couple of bamboo stakes will do the trick. Remember, unlike beans, peas, squashes etc, tomatoes are naturally ramblers and do not have tendrils that will wind and help the plant climb on its own. Use some twine to tie the plants to any stakes or cages to help hold it in place, not too tight, leaving room for the plant to grow.
If you have more than a few plants and want to give your plants more support, you can try a couple of different methods (in particular for tomatoes planted in rows): using string lines to train them up a vertical trellis or weaving lines horizontally.
For the first method, you will need tall, sturdy metal or wood stakes. These can be placed every 5-10 feet between plants. You will also need a sturdy pipe or stakes to connect to the top of the posts. Once this is rigged up, you tie string lines along the top horizontal pipe that are then dropped down and gently tied to the tomato plant. As the plant grows, you can either gently twirl the string line around the plant in a spiral or use tomato clips to secure it in place.
The Florida weave is a trellising technique that uses lines woven horizontally from post to post. You will still need sturdy, tall stakes placed every 5-10 feet. Commonly, I do 3-4 plants between posts with 1.5-2 ft between the plants, making the posts about 8 ft apart.
You start the weave by tying the string to the first post. You will “weave” the string on one side of the first plant and then the opposite side of the next plant and so on. When you reach the second post, loop around and weave back the opposite way. That way each plant is held in the weave. With multiple horizontal string lines, it will hold plants up no problem in all kinds of weather. Repeat on each section of tomatoes.
Tomatoes tend to be hearty, easy to grow plants, but there is a plethora of diseases caused by fungus, bacterial, and viral infection that can be encountered when growing them, particularly on a production level scale. However, for the home gardener, there are a few in particular to look out for and much that can be done to prevent and sometimes treat disease. Here are three conditions to look out for:
Powdery mildew is caused by fungal spores and appears white or greyish splotches. It is a disease we may see more of this summer because it thrives in damp conditions.
Blight in tomatoes is caused by a range of fungal and water mold strains. Two common forms to look out for are Early and Late Blight.
Early Blight will start with dark spots that increase in size on leaves, fruit will form black leathery spots, and stems will brown and girdle.
Late blight creates large brown splotches edged grey/green and circular infections break out on stems and fruit.
Blossom End Rot
Blossom end rot is caused by insufficient calcium in the tissue of the fruit. Calcium has been absorbed by the plant but not enough is transferred to the fruit. The fruit first appears to have a watery or bruised appearance before becoming black and sunken.
Lastly, fruit cracking is also not a disease caused challenge, but one related to watering. The interior fruit outgrows the pace of the tomato skin.
When dealing with these tomato diseases and challenges the most important tool is one of prevention.
First, it starts with the seed itself. Several diseases can be transferred through seed that was contaminated. Buy fresh, quality seed and if you have issues with specific diseases in your area, there are seeds that have been bred to be resistant to certain diseases/strains. Lastly if you save your own seed, pick the healthiest, best looking fruit to save from.
Second, grow or purchase the healthiest plants you can and give them lots of TLC. A sickly tomato plant will rarely bounce back. Better to start fresh than nurse it along.
Third, use the pruning techniques mentioned above and keep your equipment clean. A lot of tomato disease can be prevented or slowed with good air circulation.
Lastly, even a backyard garden should use crop rotation. Try and group your plants by type (nightshades, brassicas, alliums, etc) and rotate them through your plot/beds. At the least, if you have had issues with disease in tomatoes, make sure the following year to plant your nightshade veggies in a different spot, as far as you can get away (other plants like potatoes, etc can be affected by similar diseases). Any diseased plants at the end of the season should not go into your home garden compost, which will not heat up enough to kill disease, but can be put in municipal compost instead.
Diagnosing tomato diseases is tricky and often farmers will pay agricultural labs to confirm, so don’t feel bad if you’re not sure. Try your best and if the plants are getting very sickly, especially after you try some pruning, better to tear it out. Focus your energy on prevention.
Luckily, blossom end rot and cracking are fairly simple to address, the first step being consistent, even watering (however much you can control it, obviously plants outdoors will be subject to rainfall patterns). For blossom end rot, also remember to remove affected fruit so the rot does not spread. Cracked fruit can still be eaten, but do it quickly. The cracks create places for rot.
Tomato hornworms are fairly spectacular caterpillars, growing longer and thicker than one’s finger. They transform into the five-spotted hawkmoth. A full grown caterpillar will defoliate a tomato plant fairly quickly.
Aphids specialize on different groups of plants, brassicas, nightshades, etc. They are very small insects that often cluster together on the underside of leaves and leave behind a sticky residue. The major concern with aphids is they can transfer disease.
The first important step with dealing with any pest insect is to take time daily or weekly to walk your garden, inspect plants and keep an eye out for disease or pest activity. Catching things before it gets too far is key. Often to deal with these pests, simply squishing eggs and individuals (or if you’re squeamish, knocking them into soapy water buckets) can help a lot and is possible at a small scale.
However, there is another line of defence in the garden: other insects. There are a number of predatory insects that will effectively knock back pest populations. By creating a diverse garden that includes lots of flowering plants–like herbs and perennial plants–you are creating a habitat for these insects that will come for the aphids and stay for the flower pollen. The beloved lady bug, or lady beetle, is a reliable predator of aphids. While the braconid wasp is an incredible parasitic insect that lays its eggs on or in caterpillars, including the hornworm. Slowly but surely the baby wasps take care of the caterpillar for you.
This is why it is so essential not to spray pesticides in the garden. There is an incredible cycle of prey and predator insects constantly at play and with good habitat in place, there is not really a strong need for a gardener to interfere. It also illustrates why it is so important to “don’t squish it unless you know it”: the strange looking insect you squish could be a beneficial one, like this larvae of the ladybug, which loves to eat aphids.
By now, tomatoes might seem like a lot of work, but does anything compare with a ripe, homegrown tomato right off the vine? Now that you’ve ushered your plants through the season, it’s time for a delicious reward.
Try and harvest when it’s not too wet (disease prevention) and harvest fruit that is slightly underripe (unless you are eating right away). As mentioned, fruits with cracks and blemishes are fine to eat (cut out any bad spots), but don’t leave them too long or they will eventually rot. It’s good to remove these from plants and the ones not consumed can go into the compost.
Eat your fill of this bounty and consider preserving it for the winter months by canning, drying, and freezing. In my humble opinion, this time of year, there can never be too many tomatoes!
University of Wisconsin-Madison, Tomato Pruning Guide: https://pddc.wisc.edu/2021/02/09/tomato-pruning/
the art of doing stuff image, website source: https://www.theartofdoingstuff.com/turns-im-never-really-satisfied-anything-including-tomatoes/
wikiHow “How to Tie Tomatoes Using the Florida Weave- 7 Steps”: https://www.wikihow.com/Tie-Tomatoes-Using-the-Florida-Weave
UNH Cooperative Extension “Powdery mildew of greenhouse and high tunnel tomato”: https://extension.unh.edu/blog/powdery-mildew-greenhouse-high-tunnel-tomato
University of Minnesota Extension “Early Blight of Tomato”: https://extension.umn.edu/diseases/early-blight-tomato
University of Minnestoa Extension “Late blight of tomato and potato”: https://extension.umn.edu/diseases/late-blight
Michigan State University “Blossom-end rot of tomato tip sheet – MSU Extension”: https://www.canr.msu.edu/resources/blossom_end_rot_tip_sheet
University of Delaware “Fruit Cracking in Tomato | Weekly Crop Update”: https://sites.udel.edu/weeklycropupdate/?p=15595
University of Maryland Extension “Tobacco-Tomato Hornworm”: https://extension.umd.edu/resource/tobacco-tomato-hornworm-vegetables
Illinois Extension “Trouble(s) with Tomatoes”: https://extension.illinois.edu/blogs/good-growing/2020-05-01-troubles-tomatoes
University of Minnesota Extension “Tomato hornworms in home gardens”: https://extension.umn.edu/yard-and-garden-insects/tomato-hornworms
University of Wisconsin-Milwaukee “Seven-Spotted Ladybug”: https://uwm.edu/field-station/seven-spotted-ladybug/