Select a location for the plant where it can receive sufficient sunlight throughout the day. Some species of verbena may tolerate partial sun, but others tend to get various fungal diseases like powdery mildew, without sufficient sunlight.
To reduce the chances of root rot, the soil should be well drained and should contain enough coarse organic matter. If the draining capacity is not good, then it should be amended by adding around 4 inches of compost and coarse sand.
For growing verbena in containers, then the selected pot should have drainage holes at the bottom. If not add a layer of gravel before adding the soil. The pH value of the soil should be balanced, and should range between 6 to 8.
The hole which you dig for this plant should have a diameter which is double the size of the root ball of the seedling. Once the sapling is placed in the hole, pack its base tightly with soil. Mulching of around 2 inches is necessary to prevent the growth of weed, and it also helps in retaining soil moisture.
If you plan on planting verbena in groups, then make sure to keep a gap of at least 2 feet for good air circulation. In case of pots, then one seedling should be planted in each.
Once the planting procedure is complete, water the sapling. Remember to water it everyday, till the time the roots are properly established into the soil. Once this happens, you can switch to watering the plant once a week. Never pour water from the top of the plant, as it should always be given from the base.
This plant does not require a very rich soil, therefore, once a year fertilizing is good enough. There is no need to add fertilizer to a newly planted verbena, but you should start once it is about 4 inches tall. The ideal time to add fertilizer is late spring.
Use a slow release NPK (nitrogen, phosphorous, and potassium) 16-4-8 fertilizer for this purpose. During summer, if the flowering of the plant slows down, you may have to fertilize once a month. As the later summer approaches, you can stop completely.
Regular pruning of the dead flower heads during the summer is important to keep the plant bushy and promote blooms. Ideally, you should prune it after every bloom. Cut one-fourth of the stem but make sure that the main stem is not exposed. Apart from this, in the fall, you need to cut off all the damaged and disease portions completely.
These plants have a sprawling growth, so they look beautiful when grown in hanging baskets. If you have a butterfly garden, then this plant is apt for it. Take care of your verbena well, and keep it fresh and well nourished so that it attracts many butterflies.