Can chrysanthemums grow in summer conditions? - Plant Care Guide

Yes, chrysanthemums can grow in summer conditions, as summer is their primary vegetative growth period. During the summer months, chrysanthemum plants focus on developing strong root systems, lush foliage, and numerous stems. However, they do not typically bloom in summer; their spectacular flowering display is triggered by the shortening daylight hours and cooler temperatures of late summer and fall. Proper care during summer is crucial for a bountiful autumn bloom.

What is the Primary Growth Cycle of Chrysanthemums?

The primary growth cycle of chrysanthemums is characterized by distinct vegetative growth in spring and summer, followed by reproductive growth (flowering) in late summer and fall, triggered by changes in day length and temperature. Understanding this cycle is key to successful chrysanthemum cultivation.

Here's a breakdown of their typical yearly cycle:

1. Late Winter / Early Spring (Emergence & Initial Growth):
   • Hardy garden mums (perennial types) emerge from dormancy as temperatures rise. New shoots begin to appear from the crown of the plant.
   • This is the ideal time for planting new mums or dividing existing clumps.
2. Spring (Vegetative Growth - Rapid Development):
   • As daylight hours lengthen and temperatures consistently warm up, chrysanthemums enter a phase of rapid vegetative growth.
   • They develop strong root systems, multiple stems, and lush foliage. The plant's primary goal during this time is to build a robust framework that can support future blooms.
   • This is the period when pinching (removing stem tips) is crucial to encourage bushier growth and more flower buds later.
3. Summer (Continued Vegetative Growth & Bud Formation Begins):
   • Chrysanthemums continue to grow vegetatively throughout the summer. The stems lengthen, and the plant becomes larger and fuller.
   • Crucially, towards late summer (typically August to early September), as daylight hours begin to shorten and nighttime temperatures cool, the plant starts to perceive these changes. This environmental signal triggers the initiation of flower buds. While the buds are forming internally or are very tiny, they are not yet visible or opening.
   • Pinching typically ceases by mid-July (depending on region and variety) to allow flower buds to form and mature.
4. Autumn (Flowering - Reproductive Phase):
   • This is the payoff season. As days shorten further and temperatures consistently drop, the flower buds swell and begin to open, creating the spectacular autumn display.
   • Different varieties bloom at different times throughout the fall, extending the season of color.
   • This is the time when the chrysanthemum is at its peak beauty.
5. Winter (Dormancy):
   • After flowering is complete and hard frosts arrive, the foliage dies back.
   • Hardy garden mums enter a period of dormancy, conserving energy in their roots to survive the cold and emerge again next spring. Protecting the crown with mulch is often recommended.

So, while chrysanthemums are actively growing and developing in summer, they are specifically preparing for their show-stopping performance in the fall.

Why Do Chrysanthemums Not Bloom in Summer?

Chrysanthemums do not bloom in summer because they are photoperiodic plants, meaning their flowering is primarily triggered by changes in the length of daylight and darkness (photoperiod), combined with specific temperature cues. They are known as short-day plants.

Here's why summer isn't their blooming season:

• Short-Day Plant Requirement: Chrysanthemums require short days (or, more accurately, long nights) to initiate and develop flower buds.
  • During the long days of summer, there isn't a continuous period of darkness long enough to signal the plant to begin forming flower buds.
• Summer's Role: Throughout summer, the plant is in its vegetative growth phase. It focuses all its energy on developing a strong root system, growing lush foliage, and producing numerous stems. This extensive growth is essential to support the eventual large flush of flowers it will produce.
• Autumn's Trigger: As late summer transitions into fall, the days gradually become shorter, and more importantly, the nights become consistently longer. This extended period of darkness, combined with cooler nighttime temperatures, sends a crucial signal to the chrysanthemum's internal clock, telling it to switch from vegetative growth to reproductive growth – the formation and opening of flower buds.
• Temperature Influence: While day length is the primary trigger, temperature also plays a role. Consistently cool nighttime temperatures (below 60°F or 15°C) in late summer also help promote bud formation and color development. High summer heat can actually delay or inhibit bud formation, even if day length is borderline.

Essentially, summer is the chrysanthemum's training camp – a time for building strength and size – in preparation for its main performance in the autumn. Attempting to force them to bloom earlier by manipulating light (e.g., covering them to create artificial short days) is a common commercial practice but isn't usually practical for the average home gardener during natural summer conditions.

What are the Best Summer Care Practices for Chrysanthemums?

The best summer care practices for chrysanthemums focus on promoting robust vegetative growth, proper hydration, and encouraging a bushy habit in preparation for their spectacular fall bloom. Neglecting summer care can lead to weak plants and a disappointing flower display.

Here are the key practices:

1. Sunlight:
   • Full Sun: Plant chrysanthemums in a location that receives at least 6 hours of direct sunlight per day. Adequate sun during summer is crucial for strong stem development and abundant bud formation. In very hot climates, a little afternoon shade can prevent scorching.
2. Watering:
   • Consistent Moisture: Chrysanthemums need consistent moisture, especially during dry spells in summer when they are actively growing. The soil should be kept evenly moist but not waterlogged.
   • Deep Watering: Water deeply at the base of the plant to encourage strong root growth. Avoid overhead watering, which can promote fungal diseases.
   • Check Soil Regularly: Feel the top 1-2 inches of soil. If it's dry, it's time to water. A soil moisture meter can be helpful.
3. Pinching (Crucial for Bushiness and More Blooms):
   • Purpose: Pinching (also called "stopping") involves removing the top 1-2 inches of new growth from each stem. This forces the plant to branch out, creating a bushier, stronger plant with more stems, which will lead to a greater number of flowers.
   • Timing: Begin pinching when the plant is about 6-8 inches tall. Continue pinching every 2-4 weeks through late spring and early summer. Stop pinching by mid-July (or early August in warmer climates). Pinching too late will remove developing flower buds and delay or prevent blooming.
   • How to Pinch: Use your fingernails or small snips to remove the soft tip of each stem.
4. Fertilizing:
   • Moderate Feeding: Feed chrysanthemums monthly (or every 2-4 weeks for potted plants) with a balanced liquid fertilizer (e.g., 5-10-5 or 10-10-10) until buds begin to show color in late summer.
   • Avoid Over-Fertilizing: Too much nitrogen can lead to excessive leafy growth at the expense of flowers. Stop fertilizing once buds begin to form.
5. Mulching:
   • Apply a 2-3 inch layer of organic mulch (like shredded bark or compost) around the base of the plant. This helps retain soil moisture, suppress weeds, and regulate soil temperature.
6. Pest and Disease Monitoring:
   • Regularly inspect your plants for signs of common pests (aphids, spider mites) and diseases (powdery mildew). Address any issues promptly. Good air circulation through proper spacing and occasional thinning helps.
7. Support (for Taller Varieties):
   • Taller or heavily blooming varieties may benefit from staking or using a flower support ring to prevent stems from flopping over, especially once heavy with blooms.

By diligently following these summer care practices, you lay the groundwork for a spectacular display of chrysanthemums in the fall.

Can Chrysanthemums Get Sunburned in Summer?

Yes, chrysanthemums can definitely get sunburned in summer, especially if they are exposed to intense, scorching afternoon sun, or if they are moved abruptly from a shadier location to full, unfiltered sunlight without proper acclimatization. While many chrysanthemums prefer full sun, "full sun" can be relative depending on the climate zone.

Here's how sunburn manifests and why it happens:

• Symptoms of Sunburn:
  • Leaves may appear bleached, faded, or turn a grayish-green or yellow color.
  • In severe cases, the leaf tissue can become crispy, papery, and brown, particularly on the upper leaves that receive the most direct exposure. This often resembles "leaf scorch."
  • The plant may look generally stressed and listless, even if adequately watered.
• Why it Happens:
  • Intense UV Radiation: Direct, unfiltered sunlight, especially during the peak heat of summer afternoons, contains high levels of UV radiation that can damage plant cells.
  • Heat Stress: Along with light, intense sun brings excessive heat. High leaf temperatures can directly damage plant tissues and cause water to evaporate from the leaves (transpiration) at a rate faster than the roots can replenish it. This leads to dehydration and cellular collapse.
  • Lack of Acclimatization: If a chrysanthemum has been growing in a nursery or indoors in a more shaded environment, its leaves are not adapted to withstand intense sun. Moving it directly into full sun will almost certainly result in sunburn. The plant needs time to develop a thicker cuticle and adapt its cellular structure.
  • Water Deficit: If the plant is already struggling with insufficient water, it becomes much more susceptible to sunburn, as it has fewer resources to cool itself or replace lost moisture.

Prevention and Mitigation:

• Acclimatization: If you're planting nursery-bought mums or moving indoor ones outside, gradually introduce them to brighter, sunnier conditions over a week or two. Start in partial shade and slowly move them into more sun.
• Afternoon Shade in Hot Climates: In regions with extremely hot summers (e.g., Southwest, deep South), planting chrysanthemums where they receive morning sun but are protected from the harsh afternoon sun (e.g., by a taller shrub, a building, or a shade cloth) can prevent sunburn and overall heat stress.
• Consistent Watering: Ensure the plant is well-hydrated, especially during heat waves. This helps it manage water loss through transpiration.
• Mulching: A layer of mulch around the base can help keep the soil cooler and retain moisture, reducing root stress.

While sunburned leaves won't recover their green color, addressing the sun exposure issue and providing good care will allow the plant to produce new, healthy foliage.

What are the Signs of Heat Stress on Chrysanthemums in Summer?

The signs of heat stress on chrysanthemums in summer indicate that the plant is struggling to cope with excessive temperatures, often accompanied by high light intensity and low humidity. Recognizing these symptoms early is crucial to prevent long-term damage or even plant death.

Here are the key signs to look for:

• Wilting: This is often the first and most obvious sign. Leaves and stems may droop or appear limp, especially during the hottest part of the day. Unlike wilting from underwatering, the plant may still show signs of wilting even if the soil is moist, as its roots cannot supply water fast enough to compensate for transpirational loss in extreme heat.
• Leaf Scorch/Browning: As discussed, heat stress can lead to leaf scorch, where the leaf margins or tips turn brown and crispy, or entire leaves appear bleached and papery. This is a direct result of tissue damage from excessive heat and dehydration.
• Fading/Pale Foliage: Leaves may lose their vibrant green color, appearing dull, yellowish, or bleached. This indicates that the plant's chlorophyll is being damaged by the heat.
• Stunted or Slowed Growth: Instead of putting on robust growth, the plant may appear stagnant or its growth significantly slows down as it diverts energy to basic survival.
• Bud Blast or Flower Drop: If buds have already formed, severe heat stress can cause them to shrivel, turn brown, and drop off before they even get a chance to open. This is a major concern as it impacts your fall bloom.
• Reduced Flowering (or Delayed): If the plant is stressed throughout the summer, it may initiate fewer flower buds or delay their formation, resulting in a less impressive fall display.
• Increased Pest Susceptibility: Stressed plants are more vulnerable to pests like spider mites, which often thrive in hot, dry conditions.

Mitigation and Prevention:

• Provide Afternoon Shade: In regions with intense summer heat, plant chrysanthemums where they receive morning sun but are protected from the harsh afternoon sun. Use taller plants, buildings, or artificial structures like a shade cloth to offer relief.
• Consistent and Adequate Watering: Ensure the soil remains consistently moist but not soggy. Deep watering helps keep the root zone cooler.
• Mulching: A 2-3 inch layer of organic mulch around the base of the plant helps to insulate the soil, keeping roots cooler and retaining moisture.
• Avoid Over-Fertilizing: Too much nitrogen during extreme heat can force new growth that is more susceptible to heat stress.
• Choose Heat-Tolerant Varieties: If living in a very hot climate, research chrysanthemum varieties known to perform better in heat.

By recognizing these signs and implementing cooling strategies, you can help your chrysanthemums successfully navigate the summer and prepare for a brilliant fall bloom.

How Important is Pinching Chrysanthemums in Summer?

Pinching chrysanthemums in summer is incredibly important and is arguably the single most crucial summer care practice for achieving a full, bushy plant covered in abundant blooms in the fall. Without proper pinching, your chrysanthemum plant will likely become leggy, tall, and produce only a few flowers at the very tips of its stems.

Here's why pinching is so vital:

• Promotes Bushy Growth: When you pinch off the growing tip of a stem, you remove the apical bud, which produces a hormone that suppresses the growth of side shoots (axillary buds). Removing this tip breaks the apical dominance, causing the plant to send out energy to the dormant buds lower down the stem. These buds then develop into new lateral branches. This process turns a single stem into multiple stems.
• Increases Flower Count: Since each new branch has the potential to produce flowers, more branches directly translate to a significantly higher number of blooms on the plant. Instead of one flower per stem, you get many.
• Creates a Stronger Framework: Bushier plants with multiple sturdy stems are better able to support the weight of numerous flowers without flopping over.
• Controls Plant Height: Pinching helps to keep the plant more compact and prevents it from becoming overly tall and leggy, which is especially important for garden aesthetics.
• Delays Bloom Time (Slightly): Each pinch slightly delays the blooming time of that particular stem. By stopping pinching at the correct time, you ensure buds have enough time to form and open for a robust fall display.

Pinching Schedule (General Guide):

1. First Pinch: When your chrysanthemum plant is about 6-8 inches tall (usually in late spring/early summer), pinch off the top 1-2 inches of growth from all stems.
2. Subsequent Pinches: Continue pinching every 2-4 weeks as the new shoots develop and reach about 6 inches long.
3. Last Pinch: This is the most critical timing! Stop pinching by mid-July (or very early August in warmer, longer growing seasons). Pinching after this time will remove the developing flower buds that are initiated by shortening day lengths, severely delaying or even preventing your fall bloom.

How to Pinch:

• Use your thumb and forefinger to snap off the soft tip of the stem, or use small, sharp pruning snips.
• Remove only the top 1-2 inches of the stem, including a few leaves.

By diligently pinching your chrysanthemums throughout the summer, up until the critical mid-July cut-off, you are actively shaping your plant for a truly spectacular and dense display of fall flowers.

Can Fertilizing in Summer Affect Chrysanthemum Blooms?

Yes, fertilizing chrysanthemums in summer can significantly affect their blooms, especially the timing, quantity, and quality of the fall display. The type of fertilizer and the timing of application are crucial. The goal is to support strong vegetative growth early in summer without hindering bud formation later on.

Here's how summer fertilization impacts blooms:

• Early to Mid-Summer (Supports Vegetative Growth):
  • Benefit: During this period (spring through mid-July), chrysanthemums are actively growing stems and foliage. Applying a balanced fertilizer (like a 10-10-10 or 5-10-5 N-P-K ratio) or one slightly higher in nitrogen can support this robust vegetative growth. Strong, healthy stems and ample foliage are necessary to support a heavy flush of flowers later.
  • Application: Apply a granular fertilizer monthly or a liquid fertilizer every 2-4 weeks, always following package directions and watering it in well.
• Late Summer (Transition to Bud Formation - Reduce Nitrogen!):
  • Problem: As late July or early August approaches (and you stop pinching), the plant is beginning to initiate flower buds in response to shortening day lengths. Applying a high-nitrogen fertilizer at this stage can be detrimental.
  • Impact: Too much nitrogen will encourage the plant to continue producing leafy growth at the expense of flower bud development. This can result in delayed blooming, fewer flowers, or even no flowers at all if the plant prioritizes vegetative growth.
  • Recommendation: Switch to a low-nitrogen, higher-phosphorus, and potassium fertilizer (often called a "bloom booster," e.g., 5-10-10 or 2-10-10) around the time you stop pinching, or significantly reduce or stop fertilizing altogether. Some gardeners stop feeding by mid-August.
• Over-Fertilizing in General:
  • Problem: Applying too much fertilizer at any time can lead to "fertilizer burn," where excess salts draw water out of the plant's roots, causing leaf scorch, root damage, and overall stress.
  • Impact: A stressed plant will not bloom well, if at all.
  • Prevention: Always read and follow fertilizer instructions. It's better to under-fertilize slightly than over-fertilize.

In summary, fertilizing in summer is important for supporting the plant's growth leading up to bloom time. Use a balanced fertilizer early in summer, and then ensure you reduce or eliminate nitrogen as the plant transitions into its bud-setting phase in late summer to ensure a bountiful and timely autumn bloom. A general purpose garden fertilizer will suffice if used judiciously.