How Late is Too Late to Plant Tomatoes? A Guide to Optimizing Your Harvest

For many gardeners, tomatoes are the quintessential backyard crop These juicy, flavorful fruits are one of the highlights of summer and there’s nothing quite like slicing into a fresh, homegrown tomato! However, knowing the optimal time to get your tomatoes in the ground is key to maximizing your harvest Plant too early and you risk cold damage. Plant too late and your yields can suffer under summer heat. So when is too late to plant tomatoes? Let’s take a closer look.

Understanding Tomato Growing Seasons

Tomatoes thrive in warm weather. Most varieties need a long growing season of 80-100 days of temperatures between 65-85°F to reach maturity and produce fruit. This makes tomatoes a warm season crop across most regions.

Here are some general tomato planting guidelines based on common last spring and first fall frost dates

• Northern zones (last spring frost late May, first fall frost early Sept) – Set transplants out in June. You can safely plant through early July.

• Central zones (last spring frost mid April, first fall frost mid Oct) – Set out transplants in May. Planting can continue into early August.

• Southern zones (last spring frost early March, first fall frost late Nov) – Transplant in March/April. Plant through September.

These provide a good starting point, but optimal planting timing for your specific area can vary. Factors like microclimates, weather fluctuations, and variety selection matter too. Pay attention to the conditions in your own backyard.

When Spring Planting Gets Too Late

Planting tomatoes too late in spring can cause issues like

• Lack of fruit set – Hot temps above 85°F can prevent pollination and fruit set. Flowers abort.

• Poor fruit quality – Heat stress leads to catfacing, cracking, blossom end rot, etc.

• Stunted growth – Rapid daytime heating and nighttime chilling stresses plants.

• Pest/disease pressure – Hotter weather increases issues with insects, fungi, bacteria.

• Reduced yields – Plants have less time to mature fruit before summer heat hits.

As a general guideline, tomato planting in spring becomes risky after:

• Northern zones: Early July
• Central zones: Early August
• Southern zones: Mid September

But there are still steps you can take to improve results if planting late:

• Use short-season, early varieties (under 60 days to maturity).

• Provide shade, wind protection, and plenty of water.

• Use mulch and shade cloth to moderate soil temperatures.

• Pinch off new flowers that won’t have time to mature fruit.

• Focus on smaller-fruited types like cherry and grape tomatoes.

While yields may decrease, you can still enjoy a harvest from late plantings!

When Summer Planting Gets Too Late

In some regions, gardeners can plant a second tomato crop in summer for fall harvest. But planting too late in summer brings its own risks:

• Frost damage – Cool nights can damage plants, especially juveniles.

• Poor fruit set – Cooler temps and shorter days slow growth and maturity.

• Stunted plants – Less time to establish before winter dormancy.

• Lower yields – Fruits don’t have time to fully ripen before frost.

• Disease issues – Wet fall weather increases blights, mildews, and rots.

Summer planting becomes risky after:

• Northern zones: Don’t attempt a second crop

• Central zones: Mid August

• Southern zones: Early October

To improve your odds with late summer plantings:

• Use short-season varieties (under 60 days).

• Start seeds indoors in early summer to transplant later.

• Use season extending devices like cold frames or tunnels.

• Be diligent about pest/disease control with fungicides.

• Harvest green fruits before frost and ripen indoors.

While second plantings can be challenging, you can find success by selecting adapted varieties and giving special care.

Tips to Optimize Late Tomato Plantings

No matter when you end up planting, here are some useful tips to maximize success:

Pick adapted varieties – Choose compact determinate types and early cultivars (under 60 days to maturity). Some great options include:

• Siletz – early, 58 days, determinate saladette for cooler climates

• Oregon Spring – early, 60 days, determinate good for containers

• Glacier – early, 55 days, determinate, very cold tolerant

• Coldset – early, 62 days, determinate, sets fruit in cool weather

• Mountain Princess – mid, 68 days, determinate, short plant for containers

Provide protection – Use cloches, cold frames, fabric row covers, or tunnels to buffer weather swings.

Monitor soil temperature – Ideal range is 65-85°F. Use plastic mulch and floating row covers to regulate.

Use black plastic mulch – Warms soil, reduces weeds, conserves moisture.

Irrigate consistently – Provide 1-2″ of water per week, avoiding foliage wetness.

Stake/cage plants – Supports plants and fruits, improves air circulation.

Pinch off flowers – Removing excessive flowers helps direct energy into fewer mature fruits.

Control pests/disease – Be vigilant and use organic sprays to prevent insect and disease problems.

Pick early and often – Harvesting ripe tomatoes prompts more fruit set. Don’t leave fruits on stressed plants.

Protect from frost – Use covers, cloches, or move pots inside if frost threatens immature fruits.

With some special care and attention, late plantings can still yield ripe, juicy tomatoes to enjoy fresh or preserve for winter!

Should You Bother With Late Plantings?

While your harvest potential decreases, late plantings can still be worth trying depending on your goals:

For fresh eating – Less fruit but still tasty tomatoes are possible in many zones. Focus on determinate, early varieties.

For canning/freezing – You may get enough for some preserves or salsa even from stunted plants.

For fun and learning – Try different methods and varieties to improve skills for next year. Document performance.

For protected culture – A small late crop is viable in a greenhouse, tunnel, or with other season extension.

For fresh market sales – Specialty late varieties sold at premium prices can still be profitable.

Evaluate your specific objectives, be realistic in expectations, and decide if a late planting suits your needs. The experience you gain will inform future growing seasons too.

Managing Late-Planted Tomato Plants

If you do end up setting your tomatoes out past the ideal window, here are some tips for managing the plants:

Monitor soil moisture – Check soil frequently and irrigate regularly, especially during hot, dry spells.

Use reflective mulch – White plastic mulch will cool the soil and bounce light up to plants.

Stake and prune – Caging or staking keeps plants upright and supported. Removing suckers improves air circulation.

Spray leaves – Mist plants in the evening to provide cooling through evaporation.

Provide shade – Drape shade cloth or position where plants get afternoon shade if possible.

Ventilate greenhouses – Open vents and use fans to cool greenhouses and tunnels.

Fertilize lightly – Go easy on nitrogen which encourages leafy growth over fruiting.

Check for pests – Aphids, whiteflies, and other pests multiply faster in heat. Control promptly.

Scout for diseases – Be vigilant for fungal issues like blights that thrive in humidity.

Pick ripe fruits – Harvest regularly so plants aren’t trying to support mature fruits in stress.

With attentive care and management, your late-planted tomatoes can survive the challenges of growing in sub-optimal conditions.

Using Season Extension Techniques

If planting late in spring or summer, consider leveraging season extension devices:

Cold frames – Enclosed boxes with transparent tops that harness the sun’s warmth. Ventilate on warm days.

Cloches – Bell-shaped glass or plastic covers that sit over plants, acting as mini-greenhouses.

Row covers – Sheets of flexible fabric that protect from cold and pests while allowing sunlight and air exchange.

Low tunnels – Metal hoops covered in plastic that shield plants from cool weather while trapping heat.

Greenhouses – Permanent or temporary structures that create ideal growing environments for out-of-season crops.

Raised beds – Soil mounded in frames warms more quickly than ground-level beds. Use black plastic mulch for added heat.

These devices moderate temperatures, protect from wind and cold stress, and create a warmer microclimate that gives late plantings a better chance.

Summary: Key Tips for Late Tomato Plantings

To wrap up, here are some key takeaways on planting tomatoes late while still maximizing your harvest potential:

• Know your first fall frost date and count backwards based on variety days to maturity.

• Pick compact, early cultivars under 60 days for best results.

• For spring, plant late varieties no later than early July in north, early August in central zones.

• For fall, plant early varieties no later than mid August in central, early October in south zones.

• Use season extending devices like cloches, tunnels, and cold frames.

• Monitor soil temperature and aim for consistent 65-85°F range.

• Irrigate deeply and regularly while avoiding wet foliage.

• Stake, cage, or trellis plants to improve air circulation and prevent sprawling.

• Control pests and diseases right away to reduce additional stresses.

• Be diligent about picking ripe fruits to encourage further production.

While not ideal, tomato plants are resilient and reasonably hardy. With proper variety selection and care, you can still achieve viable harvests from late plantings! Just focus on giving them the best conditions possible. Here’s to a long, productive tomato season!