When Does Flowering Start Outdoor? - Outdoor Cabinets

Flowering is an exciting time in any outdoor cannabis grow. Determining exactly when flowering will start for outdoor plants depends on a few key factors. By understanding these influences, growers can better predict and prepare for the all-important flowering stage.

What Triggers Flowering in Outdoor Cannabis Plants?

The key trigger for flowering in outdoor cannabis plants is light exposure.

Specifically, it is the relative length of daylight hours compared to darkness that signals flowering to begin.
As daylight hours shorten after the summer solstice, cannabis plants receive the cue to transition from vegetative growth to flowering.
Once daylight dips below approximately 14 hours, biochemical changes initiate flowering.
This reaction to photoperiod makes cannabis a short-day plant. It enters the flowering stage as days become shorter in late summer and early fall.
Indoors, the photoperiod is controlled by growers. Outdoors, it follows natural seasonal shifts in daylight length.
Other environmental factors like temperature, humidity, and rainfall can influence flowering. But photoperiod is the primary control.

Understanding this daylight-triggered bloom onset helps predict when outdoor flowering will begin. Timing varies by geographic location and strain flowering times.

How Location Affects Start of Outdoor Flowering

The effect of latitude on seasonal daylight hours means flowering time varies across geographic zones.

Equatorial regions see consistent 12-hour days year-round. This can delay flowering unless strains are light-deprivation triggered.
Tropical and subtropical zones enter decreasing photoperiods sooner than higher latitudes. Flowering may begin in early August.
Temperate regions see bloom onset ranging from late August to early September. This covers most popular outdoor growth areas.
Cool and cold climates trigger flowering in late September or even early October. Seasons end before maturation finishes for long-flowering strains.

Elevation and local obstacles like mountains also influence daily sunlight exposure. Flowering typically begins later at higher elevations.

Microclimates in sheltered areas or urban heat islands may initiate blooming slightly sooner. But latitude remains the overriding factor affecting flowering onset.

Flowering Times Vary by Strain

Cannabis strains are often categorized by flowering length:

Short-season varieties flower in 6 to 8 weeks. These “early” strains are best for northern zones with shorter outdoor seasons.
Mid-season strains take 8 to 9 weeks to fully flower. This is suitable for most temperate outdoor grows.
Long-season varieties need 10 to 12 weeks flowering. They perform best in warmer southern climates with extended falls.
Very long season strains flower for 13 to 16 weeks. Growing these is only viable in tropical zones or with backup light-deprivation tricks.

Flowering duration should be matched to local conditions. Excessively long bloomers struggle to ripen properly in cool climates. Short flowering suits regions with early winter weather.

If unsure about regional flowering times, mid-season strains are usually a safe bet for most home growers. Stretching 9 weeks between late August and November allows reliable maturation.

Estimating Natural Flowering Start Dates

Knowing geographic and varietal factors helps estimate when outdoor flowering is likely to commence.

Several rules of thumb can guide predictions:

Add approximately 1 week delay for each 500 km north of the equator. Later flowering follows higher latitudes.
Add 1 to 2 weeks at higher elevations over 1000 meters due to reduced daylight hours.
Subtract 1 week in hot urban environments that extend summer-like conditions.
Subtract 1 to 2 weeks for short-season early flowering strains.
Add 1 to 2 weeks for long-season late flowering strains.
Medium or mid-season flowering strains will hit the averages.

Combining these gives a starting estimate. Tracking seasonal daylight changes and plant signals fine-tunes forecasts.

Typical Outdoor Flowering Start Dates

Hawaii and Southern Florida – Early to Mid August

Central and Southern California – Mid to Late August

Mediterranean Zones – Late August to Early September

Most US Temperate Zones – Early to Mid September

Northern Continental Climates – Mid to Late September

Canada and Northern US States – Late September to Early October

These ranges provide approximate guidance. Individual microclimate and seasonal variations can shift times.

Experience in a particular area will determine norms. First-time growers should start conservatively with mid-flowering strains to avoid misjudging regional flowering onset.

Plant Signs of Upcoming Flower Transition

While the light cycle triggers flowering, cannabis plants exhibit telltale signs the bloom transition approaches:

Slowing vertical growth as stem elongation decreases
Broadening leaf size that transitions from skinny vegetative leaves
Increasing side branch vigor with clustered new shoots
Early sex differentiation with pre-flowers indicating gender

These signals typically appear around 2 weeks before full flowering mode. Slowed stretching, fattening leaves, multiplying branches, and pre-flowers confirm the plants have begun hormonal and metabolic changes.

Outdoor growers should watch for these markers that flowering is imminent. They allow anticipating exact bloom time even if estimated dates prove off. Recognizing the transition helps plan and execute key tasks just before flowering hits.

Experienced outdoor growers learn to read their plants and regional conditions to narrowly predict natural flowering onset. Novices should rely more on typical timeframes and strain choices to ensure flowering success their first grows.

Optimizing the Final Veg Stage Before Flowering

The 2- to 3-week window after flowering signals appear but before full flower mode allows completing essential preparation:

Sex and select – Remove males once pre-flowers confirm sex to avoid pollination. Cull weak or defective females to focus growth on prime plants.
Supplement nutrition – Boost phosphorus and potassium in fertilizer to stock energy and mineral reserves. Reduce nitrogen to curb stretching.
Prune and train – Do final training like topping, fimming, or low-stress training to shape plants. Prune lower shaded branches and larfy growth to promote airflow.
Scout pests – Monitor for signs of bugs or disease and treat if found. Prevent infestations before flowering increases vulnerability.
Add trellising – Install individual plant support nets or strings. Get set up to manage heavy flowering colas.
Confirm security – Reinforce fences, install game cameras, and take other measures to protect ripening buds from thieves.

This pre-flowering phase is the last window to refine the grow. Ensuring plants are lean, robust, and pest-free before flowering reduces issues once buds begin swelling. Dialing in conditions now pays off in easier flowering management and heavier yields.

Outdoor Light Deprivation

While nature’s seasonal light cycle ultimately triggers cannabis flowering, some growers artificially shorten days to force earlier flowering.

Blackout tarps – These dark covers placed over plants nightly can hasten flowering by 1 to 4 weeks. But tarps must be diligently applied and removed daily.
Light deprivation greenhouse – Frames supporting blackout curtains allow automating the light period. This can force flowering and skew maturation timing but requires infrastructure.
Digging or moving – Relocating plants daily into more sheltered or darkened spaces can manipulate perceived photoperiod. This is labor-intensive.

These simulated short-day tricks advanced bloom onset. But forced flowering carries risks including stress, hermaphroditism, and reduced yields. Still, light deprivation is sometimes used in marginal seasons to finish plants.

Most home growers find it easier to select appropriate strains and anticipate natural flowering times. But the techniques can provide backup options if necessary.

Flowering Progression After Initiation

Once triggered, flowering progresses through three overlapping stages:

Early flowering – Plants stretch briefly as bud sites expand. First sticky trichomes emerge. Flower clusters are still small. (Weeks 1-3)
Peak flowering – Rapid pistil and calyx growth produce full flower clusters. Trichomes proliferate, leaves fade. Aromas strengthen and sticky resin builds. Plants bulk up. (Weeks 3-6)
Late flowering – Flowers swell with resins and cannabinoids. Pistils darken and recede. Calyxes swell with maturing seeds if pollinated. Trichome heads swell and begin turning cloudy and amber. (Weeks 6-9+)

These flowering stages bring dramatic transformation. Vegetative leaf growth transitions entirely to ripe, resinous buds over 8+ weeks.

Pistil color and trichome development mark progression through flowering. Outdoor growers time harvests based on these visible maturity indicators.

While initiation timing varies, the flowering process itself remains consistent for cannabis grown outdoors. Understanding the full bloom cycle helps manage this crucial stage for maximum yields.

Outdoor Flowering Challenges to Navigate

Outdoor flowering brings unique challenges requiring grower attention:

Pests – Flowers become highly attractive to insects. Monitor closely and control infestations.
Powdery mildew – Humid conditions increase susceptibility to PM fungus. Prevent with airflow and sulfur treatment if needed.
Botrytis (bud rot) – Dead organic matter and moisture invite this damaging mold. Remove debris and avoid wet flowers.
Mammals – Ripening smells attract deer, raccoons, bears and other pests. Use deterrents and physical barriers.
Mold – Dampness stuck inside dense flowers promotes gray mold and bud rot. Dry out plants after rains.
Wind damage – Branch breakage and bud loss from storms. Provide stability through trellising.
Temperature swings – Chilly nights followed by hot days stress maturing flowers. Little can be done beyond strain selection.
Ripening variability – Mixed maturity on different parts of plants. Harvest in phases as sections finish.

While indoor gardens allow controlling conditions, outdoor flowering is subject to seasonal variables. Vigilance and quick response to potential issues helps safeguard flowering success.

Managing Nutrition in Flowering

Flowering cannabis needs different nutritional ratios than vegetative growth.

Nitrogen – Cut back on nitrogen, which drives leafy growth. Excess N can inhibit flowering. Most strains do fine on 50-75% of veg levels.
Phosphorus – Boost phosphorus tolevels. Phosphorus supports floral development, resin and root growth. The P drives flowers.
Potassium – Increase potassium intake. Potassium (K) powers aromatic terpene production and helps floral clusters swell to maturity.
Secondary nutrients – Calcium and magnesium remain important through flowering. Epsom salts provide magnesium.
Micronutrients – Zinc, boron and manganese help enzyme production, resin buildup, and floral sites.
pH balance – Check pH to ensure optimal 5.5 to 6.5 root zone intake. Nutrient disorders show in leaves if pH is off.

These flowering fertilization tips maximize bud growth and cannabinoid content. Outdoor soils tend to be less depleted than indoor media, but may need supplementation depending on conditions and strain needs.

Timing Outdoor Cannabis Harvests

Judging optimum harvest timing is both an art and a science for outdoor growers.

Maturity – Flowers reach peak levels of cannabinoids like THC and CBD at their ripest maturity. Clear trichomes and declining pistils signal readiness.
Weather risks – Approaching winter weather, drying conditions, or mold threats may dictate earlier harvest if buds seem close enough to mature.
Strain and plant differences – Parts of the same plant reach peak at different times. Faster flowering varietals also finish sooner.
Personal preferences – Growers favoring certain effects or flavors may harvest earlier or later. Preference influences timing.
Regional norms – Outdoor harvests span from late September through November depending on location and conditions. Experience sets expectations.

Avoid over-drying flowers before taking them down. Use microscopes to monitor trichome heads and pistil color. Focus on the most mature sections when deciding harvest date.

Drying and Curing Outdoor Cannabis

Proper drying and curing processes after harvest are equally as important as grow stages for flavorful smoke. Steps include:

Slowly dry for 10-14 days under controlled humidity around 60% and temperatures of 65-75°F.
Trim leaf tips and outer sugar leaves once dry enough to handle without damaging buds. Avoid over-trimming.
Transfer into sealed containers once stems snap rather than fold. Start curing process.
Open containers daily to ventilate for the first 1-2 weeks. Gradually increase interval between air exchanges.
Cure for 4-8 weeks until buds feel sticky but stems fully brittle. Burp jars help buds “sweat out” remaining moisture.
Store cured flowers sealed in glass jars kept cool and dark to preserve terpene profiles and potency.

Rushing the dry and cure produces unpleasant harshness. Proper technique enhances smooth flavors and aromas. Patience pays off in the quality of final cured buds.

Conclusion

Predicting the transition to flowering poses a challenge for outdoor cannabis cultivators. But paying attention to photoperiod signals, strain genetics, and plant signs allows forecasting natural bloom onset within a few weeks. This guides growers to execute key preparatory tasks for nourishing ripe buds through the full flowering cycle. With proper care through the flowering stretch, outdoor plants finish with heavy yields of top-quality cannabis by harvest time.

Frequently Asked Questions About Outdoor Cannabis Flowering

Outdoor cannabis cultivators often have questions about managing the all-important flowering stage. Here are answers to some most frequently asked questions.

What causes outdoor cannabis plants to start flowering?

The primary trigger is photoperiod – the relative daily duration of sunlight and darkness. As day length shortens following the summer solstice, the light cycle signals cannabis plants to transition from vegetative growth to flowering. This makes cannabis a short-day or photoperiod-dependent plant. Other factors like temperature, humidity, and maturation age may influence bloom onset, but photoperiod drives the process.

How much light per day stops flowering?

Flowering cannabis plants will generally revert back to vegetative growth when receiving 18 hours or more of daily light. If flowered plants experience a spike in daylight such as from summer solstice to fall equinox, they can stall flowering or even return to leafy growth. Outdoors this doesn’t occur since light hours continue declining after flowering begins. But it is an issue to avoid with light leaks in indoor grows. 14-16 hours of daily light keeps cannabis plants safely in flowering mode.

Can you force outdoor plants to flower early?

Yes, “light deprivation” techniques like covering plants daily with blackout tarps can force earlier flowering. But this stresses plants and risks problems like inter-sex traits or reduced yields. It is usually better to select short-flowering varieties suited to local outdoor season length. Forcing bloom onset should be a last resort if growing strains that barely finish before winter. Letting plants follow natural seasons is ideal.

What marijuana strains have the shortest flowering times?

Pure landrace strains like Mexican and Thai flower quickest in 6-8 weeks. Afgani strains also mature rapidly. Hybrids with higher ratios of tropical and equatorial sativas tend to have shorter flowering durations suitable for northern outdoor climates. Longest flowering strains are typically indica-dominant hybrids with high northern latitude origins.

Should outdoor cannabis be given 24 hours of darkness before harvest?

This is a debated technique usually applied by indoor growers. Some believe a prolonged dark period spikes resin production right before harvest. However, research has not conclusively shown benefits from 24-48 hours of pre-harvest darkness. The science is uncertain. Outdoors, light deprivation is not feasible anyway, so most growers forgo this practice.

What causes buds to not fully mature before winter kills outdoor plants?

The most common reasons for unripe buds before winter are planting too late in the season, choosing genetics with flowering times too long for local conditions, or unusually early winter weather. To avoid this, plant early, select short-flowering strains suited to the region, and be prepared to harvest even slightly immature buds if early deep freezes threaten. An unripe bud is better than a dead plant.

What causes foxtailing of outdoor marijuana buds late in flowering?

Foxtailing happens when flower clusters stretch and distort into pointy shapes late in the bloom cycle, resembling fox tails. The causes are usually genetic tendency combined with late-season heat or humidity stress. Foxtailing buds are still usable but lack the dense, compact structure most preferred. Choosing strains resistant to foxtailing helps avoid this along with reduced handling and harvesting plants promptly once ripe.

Final Takeaways on Outdoor Cannabis Flowering

The flowering stretch is the most anticipated and rewarding stage of outdoor cannabis cultivation. To make the most of this crucial phase:

Choose suitable strains for local conditions
Watch plant signals to finetune flowering onset predictions
Perform pre-flowering preparation and maintenance
Adjust nutrients to maximize floral development
Scout constantly for flowering pests and problems
Allow proper dry and cure time for premium quality results

Learn your particular conditions, select appropriate genetics, and let nature trigger bountiful outdoor flowering each season. Stay vigilant against risks, harvest at peak maturity, and enjoy flavorful artisan cannabis grown under the sun.