Spend any time in the South and you are bound to hear this common phrase: «It’s not the heat, it’s the humidity.» While we are usually referring to our ability to withstand the summer temperature or how it affects our hairstyles, this also holds true when growing lavender, a plant that thrives on heat but doesn’t do so well in the humidity.
While there are many plants that can withstand the humidity and perform beautifully for years and years, most lavender varieties do not fare well in the Southern climate. Thankfully, breeders are developing even tougher lavender plants, so your chances of enjoying lavender in your Southern garden are increasing. Just know that even if you do everything right and your lavender plants appear happy, most lavender plants begin to decline after about 10 years.
All lavenders thrive in conditions similar to their native habitat along the Mediterranean coast – high, hot, and dry. If you want to add this beautiful and fragrant herb to your raised bed or container garden, follow these easy guidelines to ensure a plant that thrives.
|Lavender Plant Attributes|
|Family||Lamiaceae (Mint family)|
|Plant Type||Herbaceous perennial|
|Mature Size||H 2′-3′ W 2′-4′|
|Sun Exposure||Full sun|
|Soil Type||Well-drained, alkaline|
|Bloom Time||June to August|
|Hardiness Zones||5 to 8|
Lavender does not like to be crowded. Make sure you have plenty of space between your plants for airflow, especially in areas where humidity is an issue. Depending on the variety of lavender you purchase, a small potted plant can grow into a shrub that is 3 ft. in diameter; when choosing your location be mindful of any existing plants, ground cover, etc. that may eventually inhibit air circulation.
Lavender needs a lot of time in the full sun (consider the plant’s native habitat), so save the dappled areas for shade-loving plants. When adding a mature plant to your garden, choose a spot that gets sun the majority of the day.
Lavender should be planted in a well-drained, slightly alkaline soil with a pH between 6.7 and 7.3. Because lavender will not tolerate excessive soil moisture or humidity, it is a good idea to add builder’s sand to the soil before planting to aide in drainage. Create a high mound with well-cultivated soil and work in sand or pebbles to increase drainage.
Using a garden trowel, dig a hole in the mound just deep enough for the plant. Remember that lavender prefers arid conditions, both beneath and above the soil. Since hardwood mulch holds in the moisture, it is best to use a light-colored mulch, such as stone, shells, or pebbles, to help keep the plant dry.
It is important to give lavender consistent moisture, especially during the first few years while they establish a strong root system. Water low to the ground to keep moisture off the leaves; early morning is best, because the plants have time to dry before nightfall, cutting down on problems with disease.
If you water during the heat of the day, moisture tends to evaporate before plants can soak up an adequate amount. Over watering leads to root rot which will cause lavender to die. Potted lavender will need to be watered more frequently in the heat of the summer because they dry out quickly.
Temperature And Humidity
High summer humidity is not appreciated. To combat high humidity, consider using rock instead of organic mulch when planting your lavender.
As with many plants grown for their essential oils, a lean soil (soil that is lacking in very much organic material) will encourage a higher concentration of oils, so go easy on the organic matter and on the fertilizer.
Types of Lavender
There are about 47 species of lavender, with varieties that are best used for their oil and others that are enlisted for culinary purposes.
Prune to shape in spring after new leaves appear. Prune back to 8” in spring every 3 years to control plant size and to promote robust, new growth.
How To Grow Lavender From Seed
If growing lavender from seed, however, do not expose lavender seedlings to full sun while still in their nursery pots. Place them in shade and water them as needed until you plant them in the garden. It can’t be said enough – lavender thrives off of heat and does well planted alongside heat-retaining objects, such as sidewalks, along a stone wall, or around a concrete poolside.
Potting And Repotting Lavender
Follow the same instructions for planting lavender in containers, know the mature diameter of the lavender, and choose an appropriate size container. Lavender is a shallow rooted herb, so you do not need a tall pot. Average depth and spread of the root system is 8-10 inches. Because lavender requires a significant amount of sunlight, these plants do not make good houseplants, preferring to live in the garden or in a pot outdoors.
Lavender is more than just a pretty plant – use it as a natural pest repellent near patios and porches. The scent deters mosquitoes, flies, fleas, and other problem insects while attracting butterflies and bees.
Common Pests And Plant Diseases
The bacteria Xylella fastidiosa causes the Xylella disease in hundreds of different trees and shrubs, including lavender. It is extremely destructive and most commonly spread by sap-sucking insects. It’s most common in the southeast and southwest of the U.S. near moist riparian areas.
How To Get Lavender To Bloom
Reasons why your lavender plant may not be blooming do vary, and there are some easy trouble-shooting ways to identify what might be wrong. Lavender loves full sun, and if your plant is not blooming as expected, maybe there is not enough sunlight. The soil for this beautiful herbaceous shrub needs to be well drained, and also should not be too fertile. If you’ve been fertilizing too much, you are prohibiting the flower from blooming. If the soil is too acidic, this may be preventing blooms as well. Lavender loves an alkaline environment.
Common Problems With Lavender
Susceptible to leaf spot and root rot. Plants may not survive in winter if soils are not well-drained and/or if temperatures dip below zero degrees without protective snow cover.