Tomato

If you skip this, you lose real yield. The planner warns you.

How it works: Alternaria solani (early blight) and Septoria lycopersici overwinter on tomato debris and solanaceous weeds; a 2-3 year break plus debris removal starves this inoculum. Fusarium has a very narrow host range, so rotating away from the host is effective. Verticillium is the exception. Its microsclerotia persist ~10 years and it infects 300+ host families, so a garden-scale rotation does not control it.

Evidence: checked against 5 sources in the research-based literature.

The 5 sources

hgic.clemson.edu Read by a person on July 13, 2026

Tomato Diseases & Disorders Clemson HGIC

… tomatoes and related vegetables, such as potatoes, peppers, and eggplants, should not be planted on the same land more than once in three years.

content.ces.ncsu.edu Accessed July 11, 2026

Early Blight of Tomato NC State Extension

Rotate every 2-3 years.

content.ces.ncsu.edu Accessed July 11, 2026

Septoria Leaf Spot of Tomato NC State Extension

The fungus is known to overwinter on infected tomato debris and solanaceous weed hosts

content.ces.ncsu.edu Accessed July 11, 2026

Verticillium Wilt of Tomato and Eggplant NC State Extension

The pathogen can survive in the soil without a host for up to 10 years in the form of structures called microsclerotia

umass.edu Accessed July 11, 2026

Solanaceous, Verticillium Wilt UMass Extension

Verticillium wilt tends to affect a wide range of hosts and can infect many unrelated plants. Fusarium spp., on the other hand, have very narrow host ranges.

Remedy

Plant nightshades in different ground, or wait until 3 years have passed since this ground last held them. Clear and remove the old debris either way, because the inoculum overwinters on it.

Don't plant anything sensitive to walnut toxin (juglone) within a walnut tree's root zone. Nightshades are sensitive, and so are apple and cabbage. Well established

Don't plant anything sensitive to walnut toxin (juglone) within a walnut tree's root zone. Nightshades are sensitive, and so are apple and cabbage.

If you skip this, the planting fails. The planner won’t allow it.

How it works: Juglans roots exude hydrojuglone, oxidized to juglone, a respiration inhibitor. The nightshades are highly sensitive; they wilt and die.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

hort.extension.wisc.edu Read by a person on July 13, 2026

Black Walnut Toxicity UW-Madison / Wisconsin Horticulture (Joy, Hudelson & Jull, rev. 2024-02-28)

Vegetables such as tomato, potato, eggplant and pepper ... are particularly sensitive to juglone

yardandgarden.extension.iastate.edu Accessed July 13, 2026

What plants are sensitive to the juglone produced by black walnuts? Iowa State Univ. Extension & Outreach, Yard and Garden FAQ

… members of the tomato family (tomato, potato, eggplant, pepper).

Remedy

Plant it outside the walnut's root zone, which takes in the whole drip line and beyond. There is no soil treatment for juglone.

Tomato fruit set fails when night temperatures persistently exceed ~21 °C (70 °F); high day temperatures above 29-32 °C (85-90 °F) compound it. Well established

Tomato fruit set fails when night temperatures persistently exceed ~21 °C (70 °F); high day temperatures above 29-32 °C (85-90 °F) compound it.

If you skip this, you lose real yield. The planner warns you.

How it works: Sustained high day (>29-32 °C / 85-90 °F) and night (>21 °C / 70 °F) temperatures make pollen non-viable ("tacky") and impair its release; flowers go unfertilized within their ~50-hour window and abscise.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

ipm.missouri.edu Read by a person on July 13, 2026

Understanding Tomato Fruit Set Univ. of Missouri IPM

When daytime temperatures exceed 85 degrees F or nighttime temperatures exceed 70 degrees F, pollination suffers due to pollen becoming "tacky" and non-viable.

extension.umd.edu Accessed July 11, 2026

Expect Poor Fruit Set in Tomatoes This Week UMD Extension (J. Brust)

Daytime highs of 90° F and above and nighttime lows only getting down to 70° F ... will cause blossom drop and fruit abortion in tomatoes.

Remedy

Wait it out. Fruit set resumes on its own once nights cool, and the plants make up the gap. Do not reach for shade cloth. It cools the day, and this failure is driven by the night temperature, which Missouri IPM says shading will not touch. If hot nights are normal where you garden, buy a heat-set cultivar next season.

Don't sow or set out tender crops before your last frost date Well established

Don't sow or set out tender crops before your last frost date

If you skip this, the planting fails. The planner won’t allow it.

How it works: Ice nucleation in leaf tissue.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

extension.colostate.edu Read by a person on October 3, 2026

Vegetable Planting Guide Colorado State Univ. Extension, GardenNotes #720

From seed: around the date of the average last spring frost

extension.umn.edu Read by a person on October 3, 2026

Growing tomatillos and ground cherries Univ. of Minnesota Extension

Transplant to the garden after all danger of frost has passed and the soil has warmed.

Remedy

Sow or set out after the last frost date, or start indoors and transplant once it has passed.

Don't plant a crop that can't mature before your frost-free season ends Well established

Don't plant a crop that can't mature before your frost-free season ends

If you skip this, the planting fails. The planner won’t allow it.

How it works: The season's accumulated growing degree days (a running total of its warmth) against the total the crop needs to mature, or the crop's days to maturity against the number of frost-free days.

Evidence: checked against 3 sources in the research-based literature.

The 3 sources

montana.edu Read by a person on October 3, 2026

Selecting and Growing Cold-hardy Vegetables in Montana MSU Extension, LILA Fall 2023

Once you know the average dates of the last frost in spring and the first frost in fall, count the number of days between. If the “days to maturity” figure for a desired vegetable is a larger number of days and the “frost tolerance” column indicates “none,” the sad truth is that particular vegetable probably won’t grow to maturity.

planttalk.colostate.edu Read by a person on October 3, 2026

Growing Warm Season Vegetables Colorado State Univ. Extension, PlantTalk 1809

Check the seed packet for the number of days until maturity so that there will be enough time for plants to grow before the first killing frost.

extension.colostate.edu Read by a person on October 3, 2026

Vegetable Gardening in the Mountains Colorado State Univ. Extension

… high elevation areas don’t accumulate enough “growing degree units” (GDUs, also called growing degree days and heat units) to support some of the most coveted warm season vegetables

Remedy

Start it indoors and transplant it, choose a variety with fewer days to maturity, or skip this crop at this site.

Blossom-end rot comes from uneven watering, which stops calcium reaching the fruit. It is usually not caused by too little calcium in the soil. Well established

Blossom-end rot comes from uneven watering, which stops calcium reaching the fruit. It is usually not caused by too little calcium in the soil.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Calcium reaches the fruit in the water the roots draw up, carried by the xylem along with that stream. When the supply of water is interrupted the supply of calcium is interrupted with it, and the enlarging fruit runs short at its tip, even where soil calcium is adequate.

Evidence: checked against 3 sources in the research-based literature.

The 3 sources

yardandgarden.extension.iastate.edu Read by a person on August 2, 2026

Blossom End Rot Iowa State Univ. Extension, Yard & Garden

This is a problem born of calcium deficiency, most often the result of erratic watering.

extension.umd.edu Read by a person on August 2, 2026

Blossom End Rot on Vegetables Univ. of Maryland Extension

Mix in 1/4 cup of gypsum (calcium sulfate) with the soil from each planting hole

hgic.clemson.edu Read by a person on August 2, 2026

Gardening Myths: Fix Blossom End Rot with Calcium Sprays Clemson HGIC

Calcium is taken up from the soil through the plants

Plus one working note on how the sources were read.

Remedy

Keep the soil evenly moist, without letting it dry out and then soaking it, and mulch to hold that moisture steady. We are not naming a calcium amendment or a rate, because the sources disagree on whether adding calcium helps at all, and any amendment number would need a soil test first.

A tomato transplant goes into the ground deeper than it grew in its pot, buried up to its first leaves. It does not go in at the soil line it came out of. Well established

A tomato transplant goes into the ground deeper than it grew in its pot, buried up to its first leaves. It does not go in at the soil line it came out of.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: A tomato's stem forms roots along whatever length of it is buried in moist soil. Setting the plant deep therefore converts stem into root, and the plant ends up with a larger root system than the one that came out of the pot.

Evidence: checked against 1 source in the research-based literature.

The source

extension.usu.edu Read by a person on August 3, 2026

Tomato, Pepper & Eggplant: Planting & Spacing Utah State Univ. Extension

The stem of a tomato transplant may be buried in soil up to the first leaves (or more if the plant is spindly)

Plus one working note on how the sources were read.

Remedy

When you set it out, bury the stem up to the first leaves, or deeper still if the plant is leggy from being started indoors. This is the one seedling you plant lower than it was growing.

Late blight comes back from last year's potatoes. It does not come back from the soil. Tubers left in the ground carry it through winter as volunteers, so ground that grew potatoes last season needs its volunteers pulled before this year's tomatoes or potatoes go in. Promising

Late blight comes back from last year's potatoes. It does not come back from the soil. Tubers left in the ground carry it through winter as volunteers, so ground that grew potatoes last season needs its volunteers pulled before this year's tomatoes or potatoes go in.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Phytophthora infestans needs living tissue to overwinter. Infected tubers left in the ground, in a compost heap that does not freeze, or in a cull pile survive and sprout as volunteers that carry the blight into the new season; tomatoes do not carry it, because frost kills the whole plant and the seed is clean.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

umass.edu Read by a person on September 2, 2026

Late Blight Management for Fall, Winter and Spring UMass Extension

Potato tubers that are infected with late blight and don't freeze or decay during the winter can carry the pathogen over the winter to next spring

extension.umn.edu Read by a person on September 2, 2026

Late blight of tomato and potato UMN Extension

P. infestans can overwinter in Minnesota if protected in potato cull piles

Remedy

From April to June, walk last year's potato ground and any compost or cull pile, pull every volunteer potato and put it in the bin. Don't compost it. Then plant.

Pests of one plant family spread more easily through a solid block of it A good hunch

Pests of one plant family spread more easily through a solid block of it

A good hunch

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Resource concentration. A specialist locates and holds its host more efficiently at higher host density and continuity, so an unbroken run of one family across adjacent beds is an easier target than the same family separated by a non-host (associational resistance).

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

Read by a person on August 21, 2026

Organization of a plant-arthropod association in simple and diverse habitats: the fauna of collards (Brassica oleracea) Root 1973

… the resource concentration hypothesis, which states that herbivores are more likely to find and remain on hosts that are growing in dense or nearly pure stands; that the most specialized species frequently attain higher relative densities in simple environments.

Read by a person on August 21, 2026

Flea beetle movement in a broccoli monoculture and diculture Elmstrom, Andow & Barclay 1988

… strong, direct support for the hypothesis that host plants are harder to find and easier to lose in vegetationally diverse habitats than in monocultures.

Remedy

Where one family fills adjacent beds in a single season, breaking the run with a non-host family between them lengthens the distance the specialist must travel to the next host. The app discloses this and never docks a score. A continuous single-family block can be the right call anyway (a wind-pollinated crop like corn sets better massed), so the app names the trade-off and leaves the choice to the gardener.

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself. Promising

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Cold hardiness. Hardy crops tolerate hard frost and half-hardy crops tolerate light frost, so they can occupy the ground weeks before frost-tender crops are allowed in. The offset is measured from the last spring frost.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

extension.illinois.edu

Time Your Vegetable Plantings by Cold Hardiness University of Illinois Extension

… withstand freezing temperatures and hard frosts without injury

extension.colostate.edu Read by a person on September 30, 2026

Vegetable Planting Guide Colorado State Univ. Extension, GardenNotes #720

As early as 2-4 weeks before the date of the average last spring frost

Plus 2 working notes on how the sources were read.

Long-season warm crops are started indoors several weeks before the last frost and set out after it. Tomato and tomatillo go about six weeks ahead, pepper and eggplant about eight, basil six. Promising

Long-season warm crops are started indoors several weeks before the last frost and set out after it. Tomato and tomatillo go about six weeks ahead, pepper and eggplant about eight, basil six.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: A frost-tender crop with a long days-to-maturity cannot mature if it is only direct-sown after the last frost, because the frost-free window is too short. A head start under cover buys the weeks the season lacks; the seedling is set out only once frost has passed, so the transplant date is still frost-gated.

Evidence: checked against 3 sources in the research-based literature.

The 3 sources

extension.umn.edu Read by a person on July 25, 2026

Starting seeds indoors University of Minnesota Extension

We summarise this source in our notes rather than quote a line from it.

extension.illinois.edu Read by a person on October 10, 2026

When should I start my seeds? University of Illinois Extension

Early-to-mid-March Vegetables & herbs: artichoke, broccoli, cabbage, cauliflower, eggplant, kale, lettuce, oregano

extension.umd.edu Read by a person on October 10, 2026

Starting Vegetable Seeds Indoors University of Maryland Extension

Tomato: 5 to 6 weeks

Over-feeding a tomato with nitrogen grows a tall, dark-green, leafy plant that flowers late and sets little fruit. The plant pours its resources into vines and foliage instead of blossoms, so flowering is delayed or sparse and yield drops. It's an imbalance between vegetative growth (leaves and stems) and reproductive growth (flowers and fruit), and it comes from how you fertilize. It is a different problem from the heat that makes already-open flowers fail to hold, so keep the two apart. Promising

Over-feeding a tomato with nitrogen grows a tall, dark-green, leafy plant that flowers late and sets little fruit. The plant pours its resources into vines and foliage instead of blossoms, so flowering is delayed or sparse and yield drops. It's an imbalance between vegetative growth (leaves and stems) and reproductive growth (flowers and fruit), and it comes from how you fertilize. It is a different problem from the heat that makes already-open flowers fail to hold, so keep the two apart.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: High available nitrogen biases the plant toward vegetative growth. Abundant nitrogen keeps it building leaves and stems, and that leaf-and-stem growth takes priority over the switch into flowering, so flower initiation is delayed and fewer flowers form. The visible result is lush dark foliage with reduced and later fruit set, with the growth spent on leaves and stems.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

fieldreport.caes.uga.edu Accessed August 22, 2026

Troubleshooting Cultural Problems in Tomatoes UGA Extension

Too much nitrogen is also a common problem, and can be identified when the plant is tall and dark green, with excessive growth and no blooming.

extension.missouri.edu Accessed August 22, 2026

Watering and Fertilizing Tomatoes in a High Tunnel Univ. of Missouri Extension

Too much nitrogen creates excessive vine growth, twisted foliage, delayed flowering and lower yield.

Remedy

Go easy on nitrogen, especially before fruit set; do not feed a tomato a nitrogen-heavy fertilizer at planting and hold off feeding again until flowers and small fruit have appeared. Let a soil test say what the bed actually needs. The planner doesn't guess at NPK numbers.

Brown leaf spots with target-like rings, starting on the lower leaves of tomato or potato, are early blight, a fungus that overwinters in plant debris and soil and reaches the leaves by soil splash. Promising

Brown leaf spots with target-like rings, starting on the lower leaves of tomato or potato, are early blight, a fungus that overwinters in plant debris and soil and reaches the leaves by soil splash.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: The early blight fungi overwinter in infected plant debris and in the soil. Lower leaves are infected when they touch contaminated soil or when rain splashes soil up onto them; the spores need free water or very high humidity to germinate. Spots enlarge with concentric rings, and fruit can form leathery black spots.

Evidence: checked against 1 source in the research-based literature.

The source

extension.umn.edu Read by a person on September 25, 2026

Early blight in tomato and potato UMN Extension

Larger spots have target-like concentric rings.

Remedy

Mulch the soil under the plants and stake them, to keep soil and leaves apart; water at the base and keep it off the leaves. Remove spotted leaves early, but no more than a third of the plant. Grow resistant varieties (often marked EB), rotate out of tomatoes and their relatives for at least two years, and remove or bury infected plants in the fall.

Lower tomato leaves that yellow after dark spots appear have a fungal leaf disease (early blight or Septoria leaf spot); leaves that yellow without spots, especially in containers, can be short of nitrogen. Promising

Lower tomato leaves that yellow after dark spots appear have a fungal leaf disease (early blight or Septoria leaf spot); leaves that yellow without spots, especially in containers, can be short of nitrogen.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Early blight and Septoria leaf spot are fungal diseases that begin on the lower foliage in wet weather as deep brown or blackish spots, followed by yellowing or browning of the leaves. Early blight has target-like rings, and Septoria has whitish centers and dark borders. Separately, tomato leaves can yellow from a lack of nitrogen, which is common in containers because frequent watering and low soil fertility leave little of it.

Evidence: checked against 1 source in the research-based literature.

The source

hort.extension.wisc.edu Read by a person on September 25, 2026

Troubleshooting Tomato Problems UW-Madison Extension (Wisconsin Horticulture)

Early blight and septoria leafspot are fungal leaf diseases infecting tomato plants, especially during wet weather.

Remedy

Where the yellowing began with spots, treat it as leaf disease. Remove the infected leaves, mulch to stop soil splashing onto the lower leaves, space or stake for air, and rotate and choose resistant varieties next year. Where the leaves yellow without spots, nitrogen may be short. Get a soil test before feeding, and do not over-apply.

Very tender crops go out about two weeks after the average last spring frost: tomato, pepper, eggplant, lima beans, melons, watermelon, pumpkin and winter squash. Tender crops go in at the frost itself. Promising

Very tender crops go out about two weeks after the average last spring frost: tomato, pepper, eggplant, lima beans, melons, watermelon, pumpkin and winter squash. Tender crops go in at the frost itself.

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Chilling. A very tender crop is hurt by cool weather as well as by frost: it needs daytime temperatures above 60 °F, and a week of days below 55 °F can stunt it. Setting it out about two weeks after the average last frost gives the days time to warm.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

extension.colostate.edu Read by a person on September 30, 2026

Vegetable Planting Guide Colorado State Univ. Extension, GardenNotes #720

Typically 2+ weeks after the average last spring frost date

extension.illinois.edu Read by a person on October 1, 2026

Time Your Vegetable Plantings by Cold Hardiness University of Illinois Extension

Warm-loving vegetables are intolerant of frost and cold and are typically planted between May 10 and June 1.

Frost can form on a night the forecast low is a few degrees above freezing. Promising

Frost can form on a night the forecast low is a few degrees above freezing.

If you skip this, the planting fails. The planner warns you.

How it works: On a clear, still night leaves lose heat to the open sky, so a leaf can fall to freezing and ice can form in it while the thermometer, a couple of meters up, still reads a few degrees above.

Evidence: checked against 7 sources in the research-based literature.

The 7 sources

www.weather.gov Read by a person on October 14, 2026

Frost and Freeze Information NWS Tallahassee

Issued up to 24 hours when temperature is forecast to be between 32° and 36° on nights with calm winds

www.weather.gov Read by a person on October 14, 2026

Freeze Watches and Warnings National Weather Service

… temperatures below 28°F for an extended period of time can kill most types of commercial crops and residential plants.

ipm.ucanr.edu Read by a person on October 14, 2026

Freezing and Frost UC Statewide IPM Program

Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.

yardandgarden.extension.iastate.edu Read by a person on October 14, 2026

Fall Planting of Vegetables Iowa State University Yard and Garden, Aaron Steil and Kim Hilgers

Tender crops will be damaged or destroyed by a light frost

extension.sdstate.edu Read by a person on October 14, 2026

Fall Frost Tolerance of Common Vegetables SDSU Extension, Rhoda Burrows

Crops from more-temperate regions can withstand light freezes (28 to 32 degrees Fahrenheit):

extension.umn.edu Read by a person on October 14, 2026

A Minnesota guide to garden timing UMN Extension, Robin Trott

A light frost (32°F) can damage tender plants, while a hard frost (28°F or colder) will kill most warm-season crops.

extension.colostate.edu Read by a person on October 14, 2026

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson

Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat.

Remedy

The evening before, cover the crops at risk with a sheet or frost cloth, never plastic, reaching the ground and loose at the bottom so the soil's warmth can rise under it, and take it off in the morning. A cover helps least in a long, hard freeze.

Technical manual on small-scale processing of fruits and vegetables FAO

Where frost is rare, sow so the crop grows through months that suit it. A good hunch

Where frost is rare, sow so the crop grows through months that suit it.

A good hunch

If you skip this, you lose real yield. The planner suggests it.

How it works: A crop grows and makes its harvest within a band of warmth: in months colder than its band it grows too slowly to finish, and in months hotter than it a cool-season crop bolts and turns bitter while a warm-season crop drops its flowers.

Evidence: checked against 9 sources in the research-based literature.

The 9 sources

oc4h.ucanr.edu Read by a person on October 15, 2026

Vegetable Characteristics UC Cooperative Extension Placer/Nevada Counties, publication 31-043C

Optimum Temperatures for Different Vegetables

www.ucanr.edu Read by a person on October 15, 2026

Hold the Tomatoes! UC Master Gardeners of Monterey, San Benito and Santa Cruz Counties, Jazmin Lopez

Average monthly temperatures for cool-season crops during their growing period: 60-65F. This includes, carrots, parsnips, spinach, lettuce, broccoli, and garlic to name a few.

www.fao.org Read by a person on October 15, 2026

Group D: These vegetables thrive in areas where the mean monthly temperatures range between 15 and 18°C. They are intolerant to temperatures between 21 and 24°C, and tolerate weak frosts. This group includes spinach, lettuce, broccoli, beetroot, Brussels sprout, cabbage, radish, rhubarb and watercress.

content.ces.ncsu.edu Read by a person on October 15, 2026

16. Vegetable Gardening NC State Extension, Extension Gardener Handbook

Summer. As temperatures rise, cool-season crops bolt and become bitter.

extension.umd.edu Read by a person on October 15, 2026

Poor Blossom and Fruit Set of Vegetables University of Maryland Extension

Night temperatures below 60° F. and above 75° F. or day temperatures above 95° F. can cause pepper flowers and small fruits to drop.

daf.nt.gov Read by a person on October 15, 2026

Lettuce Northern Territory Government, Agnote B1

In the Top End climate lettuce plantings are restricted to the cooler months from April till July. Hot weather makes the plants to bolt, as they do not form a head but flower instead.

daf.nt.gov Read by a person on October 15, 2026

Cabbages Northern Territory Government, Agnote B3

Cabbages are a cool climate crop and their planting in the Top End is restricted from the end of March through to July.

daf.nt.gov Read by a person on October 15, 2026

Onions Northern Territory Government, Agnote B9

Onions can be grown only in the cooler months in the Top End, which limits planting from the end of March to the end of May.

edis.ifas.ufl.edu Read by a person on October 15, 2026

Florida Vegetable Gardening Guide UF/IFAS EDIS SP103/VH021, Park-Brown, Saracino, Williams and Treadwell

Leaf types grow well in Florida; grow crisphead type only in coolest months.

Remedy

Sow in the months the app names. Outside them, grow a crop whose months they are, or a variety bred for the heat or the cool.

Tomatoes, peppers and eggplant set little fruit while the nights stay cool. Promising

Tomatoes, peppers and eggplant set little fruit while the nights stay cool.

If you skip this, you lose real yield. The planner warns you.

How it works: Low temperatures cut the pollen's viability and slow the growth of the pollen tube, so the flowers drop without setting fruit.

Evidence: checked against 4 sources in the research-based literature.

The 4 sources

Read by a person on October 15, 2026

Extreme temperature effects on tomato and pepper crops Ontario Ministry of Agriculture, Food and Agribusiness

Less than 13°C (55°F)

extension.umd.edu Read by a person on October 15, 2026

Poor Blossom and Fruit Set of Vegetables University of Maryland Extension

Night temperatures below 60° F. and above 75° F. or day temperatures above 95° F. can cause pepper flowers and small fruits to drop.

content.ces.ncsu.edu Read by a person on October 15, 2026

16. Vegetable Gardening NC State Extension, Extension Gardener Handbook

This occurs when nighttime temperatures fall below 55°F or stay above 70°F, or daytime temperatures rise above 90°F for extended periods.

ipm.missouri.edu Read by a person on October 15, 2026

Understanding Tomato Fruit Set University of Missouri IPM, David Trinklein

Conversely, nighttime temperatures below 55 degrees F also promotes blossom drop.

Remedy

Time the planting so it flowers in months whose nights are warmer than that, and grow a cool-season crop through the coldest months.

Where frost sets the season, a crop still needs enough warm months to reach harvest. A good hunch

Where frost sets the season, a crop still needs enough warm months to reach harvest.

A good hunch

If you skip this, you lose real yield. The planner suggests it.

How it works: A crop grows at the pace its days to maturity assume only in months at least as warm as the low end of its band, and in cooler months it grows too slowly to finish, so a frost-free season of cool months can end before the crop is ready.

Evidence: not yet confirmed. It is cited to 8 sources, which a person has yet to read.

What this rests on - 8 pointers

oc4h.ucanr.edu Read by a person on October 15, 2026

Vegetable Characteristics UC Cooperative Extension Placer/Nevada Counties, publication 31-043C

Optimum Temperatures for Different Vegetables

www.ucanr.edu Read by a person on October 15, 2026

Hold the Tomatoes! UC Master Gardeners of Monterey, San Benito and Santa Cruz Counties, Jazmin Lopez

Average monthly temperatures for warm season crops during their growing period: 65-80F. This includes melons, corn, eggplant, peppers, squash, and tomatoes.

extension.colostate.edu Not yet read by a person

Vegetable Gardening in the Mountains Colorado State University Extension

Of the warm season vegetables, bush beans and summer squash are the most likely to succeed.

extension.umn.edu Not yet read by a person

Growing eggplant in home gardens University of Minnesota Extension

Eggplant needs warm conditions, and will not thrive during a cool season. There are varieties available that thrive in Minnesota’s short summer season.

extension.umn.edu Not yet read by a person

Growing peppers University of Minnesota Extension

In general, smaller-fruited peppers are more tolerant of both cool and hot temperatures

extension.oregonstate.edu Not yet read by a person

Growing vegetables in the Pacific Northwest coastal region Oregon State University Extension, EM 9695

Cold rain, wind, and cool nights can keep coastal soils cold well into summer.

extension.oregonstate.edu Not yet read by a person

Coastal gardening: How to succeed in wind and microclimates Oregon State University Extension

There are some things you can’t do very well on the coast, like tomatoes,

solutions.tennessee.edu Read by a person on October 20, 2026

Fall Vegetable Gardens University of Tennessee Agricultural Extension Service, SP291G

Most seed packets and variety descriptions in catalogs estimate the days from planting to maturity. Add about 10 days to this estimate because of the cooler, shorter days in the fall.

Plus one working note on how the sources were read.

Remedy

Grow it under cover, in a greenhouse, tunnel or cloche; start it early indoors and choose its quickest variety; or grow a crop whose months these are.