How to Prune Verbena for Bountiful Blooms: A Comprehensive Guide
Verbena, with its vibrant clusters of flowers and long bloom season, is a popular choice for gardens and containers. Regular pruning is essential to keep verbena plants healthy, encourage abundant blooms, and maintain an attractive shape. This comprehensive guide will walk you through everything you need to know about pruning verbena, from the best time to prune to specific techniques for different types of verbena.
Why Prune Verbena?
Pruning verbena isn’t just about aesthetics; it’s crucial for the plant’s overall health and performance. Here’s why regular pruning is essential:
* **Encourages Blooming:** Verbena blooms on new growth. Pruning stimulates the plant to produce more new shoots, leading to a profusion of flowers.
* **Removes Dead or Diseased Growth:** Removing dead, damaged, or diseased stems prevents the spread of infection and allows the plant to focus its energy on healthy growth.
* **Improves Air Circulation:** A dense, unpruned verbena can suffer from poor air circulation, making it susceptible to fungal diseases. Pruning opens up the plant, allowing air to circulate freely.
* **Maintains Shape and Size:** Verbena can become leggy and sprawling if left unpruned. Regular pruning helps maintain a compact, attractive shape and prevents the plant from overcrowding its neighbors.
* **Prevents Seed Production (in some cases):** Some verbena varieties are prone to self-seeding, which can be undesirable. Deadheading spent flowers can help prevent this.
Types of Verbena
Before you start pruning, it’s important to identify the type of verbena you have. There are several different types, and their growth habits and pruning needs may vary slightly:
* **Trailing Verbena (Verbena x hybrida):** This type of verbena is characterized by its spreading, cascading growth habit. It’s often used in hanging baskets, containers, and as a ground cover. Popular varieties include ‘Superbena’ and ‘Lanai.’
* **Upright Verbena (Verbena bonariensis):** Also known as Tall Verbena or Argentinian Verbena, this type grows tall and upright, reaching heights of 3-6 feet. It features airy stems topped with clusters of small, purple flowers. It’s a favorite for attracting butterflies and other pollinators.
* **Clump-Forming Verbena (Verbena canadensis):** This type forms a dense clump of foliage and flowers. It’s a good choice for borders, rock gardens, and containers. Popular varieties include ‘Homestead Purple’ and ‘Emma.”
When to Prune Verbena
The best time to prune verbena depends on the type and the desired outcome.
* **Early Spring:** A light pruning in early spring, just as new growth emerges, can help remove any dead or damaged stems from the winter and encourage bushier growth. This is particularly important for trailing verbena, which can become leggy over the winter.
* **Throughout the Growing Season:** Regular deadheading throughout the growing season is essential to keep verbena blooming. Deadheading involves removing spent flowers to prevent seed production and encourage the plant to produce more blooms.
* **Mid-Summer:** A more significant pruning in mid-summer can help rejuvenate verbena plants that have become leggy or sparse. This is especially beneficial for trailing verbena, which can start to look tired by mid-summer.
* **Late Fall/Early Winter (in colder climates):** After the first frost, you can cut back verbena plants to tidy them up for the winter. However, avoid pruning too heavily in the fall, as this can make the plants more susceptible to winter damage. In warmer climates, you may not need to prune at all in the fall.
Tools You’ll Need
* **Pruning Shears or Scissors:** Use sharp, clean pruning shears or scissors to make clean cuts. Dull blades can crush stems and damage the plant. Bypass pruners are generally preferred over anvil pruners for cleaner cuts.
* **Gloves:** Wear gloves to protect your hands from thorns and potential irritants.
* **Rubbing Alcohol or Bleach Solution:** Sterilize your pruning shears before and after pruning to prevent the spread of disease. You can use rubbing alcohol or a diluted bleach solution (1 part bleach to 9 parts water).
* **Optional: Hand Trowel:** If you’re pruning verbena in a container, you may need a hand trowel to loosen the soil around the plant.
How to Prune Trailing Verbena (Verbena x hybrida)
Trailing verbena benefits from regular pruning to maintain its shape, encourage blooming, and prevent it from becoming leggy.
**Step 1: Sterilize Your Pruning Shears:** Dip your pruning shears in rubbing alcohol or a diluted bleach solution to sterilize them.
**Step 2: Remove Dead or Diseased Growth:** Inspect the plant for any dead, damaged, or diseased stems. Cut these stems back to the base of the plant or to a healthy lateral shoot.
**Step 3: Deadhead Spent Flowers:** Remove any spent or faded flowers by cutting the stem just below the flower head. This will encourage the plant to produce more blooms.
**Step 4: Trim Back Leggy Stems:** If the plant has become leggy, trim back the longest stems by about one-third to one-half. This will encourage bushier growth.
**Step 5: Shape the Plant:** Use your pruning shears to shape the plant as desired. You can trim back stems that are growing in unwanted directions or that are overcrowding the plant.
**Step 6: Repeat Regularly:** Repeat this process every few weeks throughout the growing season to keep the plant looking its best.
**Specific Techniques for Trailing Verbena:**
* **Pinching:** Pinching is a technique that involves removing the tips of new shoots to encourage branching. Pinching can be done regularly throughout the growing season to create a bushier, more compact plant.
* **Rejuvenation Pruning:** If your trailing verbena has become very leggy and sparse, you can give it a more drastic rejuvenation pruning in mid-summer. Cut the plant back by about one-half to two-thirds. This may seem drastic, but it will encourage the plant to produce new growth and bloom again in the fall.
How to Prune Upright Verbena (Verbena bonariensis)
Upright verbena, also known as Verbena bonariensis or Tall Verbena, requires slightly different pruning techniques than trailing verbena.
**Step 1: Sterilize Your Pruning Shears:** Dip your pruning shears in rubbing alcohol or a diluted bleach solution to sterilize them.
**Step 2: Remove Dead or Diseased Growth:** Inspect the plant for any dead, damaged, or diseased stems. Cut these stems back to the base of the plant or to a healthy lateral shoot.
**Step 3: Deadhead Spent Flowers:** Remove any spent or faded flowers by cutting the stem just below the flower head. This will encourage the plant to produce more blooms. However, some gardeners like to leave the seed heads on Verbena bonariensis to attract birds during the winter.
**Step 4: Control Height and Spread:** Verbena bonariensis can grow quite tall, so you may need to prune it to control its height and spread. You can cut back the stems by about one-third to one-half to keep the plant at a manageable size. This is best done in early spring.
**Step 5: Thin Out Stems:** Verbena bonariensis can become quite dense, so it’s important to thin out the stems to improve air circulation. Remove some of the inner stems to allow more light and air to reach the center of the plant.
**Step 6: Optional: Cut Back Hard in Late Fall/Early Winter:** In colder climates, you can cut back Verbena bonariensis to the ground after the first frost. However, in warmer climates, you may not need to prune it back at all. Many gardeners prefer to leave the dried seed heads on the plant for winter interest and to provide food for birds.
**Specific Techniques for Upright Verbena:**
* **Pinching (Early Stages):** While not as crucial as with trailing verbena, pinching young Verbena bonariensis plants can encourage branching and create a sturdier plant.
* **Selective Pruning:** Focus on selectively removing stems that are crossing, rubbing, or growing in unwanted directions. This will help improve air circulation and prevent the plant from becoming overcrowded.
How to Prune Clump-Forming Verbena (Verbena canadensis)
Clump-forming verbena varieties, such as Verbena canadensis, have their own specific pruning requirements.
**Step 1: Sterilize Your Pruning Shears:** Dip your pruning shears in rubbing alcohol or a diluted bleach solution to sterilize them.
**Step 2: Remove Dead or Diseased Growth:** Inspect the plant for any dead, damaged, or diseased stems. Cut these stems back to the base of the plant or to a healthy lateral shoot.
**Step 3: Deadhead Spent Flowers:** Regular deadheading is crucial for clump-forming verbena to encourage continuous blooming. Remove spent flowers by cutting the stem just below the flower head.
**Step 4: Trim Back After Blooming Flush:** After the initial flush of blooms in the spring or early summer, you can trim back the entire plant by about one-third to one-half. This will encourage a second flush of blooms later in the season.
**Step 5: Divide if Necessary:** Over time, clump-forming verbena can become overcrowded. If this happens, you can divide the plant in the spring or fall to create new plants. Dig up the clump and carefully separate it into smaller sections, each with its own roots and shoots. Replant the sections in well-draining soil.
**Specific Techniques for Clump-Forming Verbena:**
* **Shearing:** You can use shearing to quickly remove spent flowers and tidy up the plant. Use hedge shears or scissors to shear off the top few inches of the plant after the initial bloom flush.
* **Renewal Pruning:** If the plant becomes woody or unproductive, you can perform a renewal pruning in the early spring. Cut back all of the stems to just a few inches above the ground. This may seem drastic, but it will encourage the plant to produce new growth and bloom again in the summer.
General Pruning Tips for All Verbena Types
* **Make Clean Cuts:** Always use sharp, clean pruning shears to make clean cuts. Avoid tearing or crushing the stems, as this can damage the plant and make it more susceptible to disease.
* **Cut at a 45-Degree Angle:** When pruning, cut stems at a 45-degree angle just above a node (the point where a leaf or stem emerges from the main stem). This will encourage new growth to emerge from the node.
* **Don’t Remove More Than One-Third of the Plant at a Time:** Avoid removing more than one-third of the plant’s growth at any one time, as this can stress the plant.
* **Sterilize Your Pruning Shears Regularly:** Sterilize your pruning shears before and after pruning each plant to prevent the spread of disease.
* **Dispose of Prunings Properly:** Dispose of any diseased or infested prunings properly to prevent the spread of problems to other plants. You can burn them, bury them, or dispose of them in a sealed plastic bag.
* **Water and Fertilize After Pruning:** After pruning, water and fertilize the plant to help it recover and encourage new growth. Use a balanced fertilizer or a fertilizer specifically formulated for flowering plants.
* **Observe Your Plants:** Pay attention to how your verbena plants respond to pruning. Different varieties and growing conditions may require different pruning techniques. Adjust your pruning practices as needed to achieve the best results.
Troubleshooting Common Pruning Problems
* **Plant Doesn’t Bloom After Pruning:** If your verbena doesn’t bloom after pruning, it could be due to several factors. Make sure you’re deadheading regularly to encourage new blooms. Also, ensure that the plant is getting enough sunlight and fertilizer. Over-fertilizing with nitrogen can promote foliage growth at the expense of flowers.
* **Plant Becomes Leggy Again Quickly:** If your verbena becomes leggy again quickly after pruning, it may be due to insufficient sunlight. Move the plant to a sunnier location or provide supplemental lighting. Regular pinching can also help prevent legginess.
* **Plant Develops Disease After Pruning:** If your verbena develops disease after pruning, it could be due to using dirty pruning shears. Always sterilize your pruning shears before and after pruning each plant. Also, ensure that the plant has good air circulation and is not being overwatered.
Conclusion
Pruning verbena is a simple but essential task that will keep your plants healthy, attractive, and blooming profusely. By following the tips and techniques in this guide, you can ensure that your verbena plants thrive and provide you with a season-long display of beautiful flowers. Remember to identify the type of verbena you have, prune at the appropriate times, and use clean, sharp pruning shears. With a little care and attention, you can enjoy the beauty of verbena in your garden for years to come.