The Garden Guy: Living with Lavender

Garden Guy Bruce Bennett

By Bruce Bennett

Last summer was a prime growing season for lavender in the Greater Seattle area and several questions concerning this versatile sub-shrub did hit my email in-box. Consequently, in preparation for this summer, let’s talk about several forms of this great Mediterranean perennial which might fit well in your landscape. 

We’ll also figure out why one person’s lavender thrives and their neighbor’s is good for only the compost pile. The reasons are fairly simple; lavender type, drainage and good intentions. Let’s talk details...

Western Washington is considered to have a moderate Mediterranean Climate or, more precisely, a Summer-Dry Climate. Virtually all types of lavender (botanical name: Lavandula) will enjoy our summers. But, we also want plants that can survive our damp, cold winters. In this case, not all varieties make the cut.

Lavender fields. Photos courtesy pixers.uk

There are more than four hundred varieties of lavender. 

Depending on parentage, the one-gallon little guy you crave from the nursery could be classified as tender, half-hardy or hardy in our USDA Zone 8 region. 

Each of the three groups have their own pros and cons. These distinct differences will determine where you can successfully grow them. 

When you are shopping at your favorite garden center, you will probably see Lavandula angustifolia (English Lavender), L. x intermedia (aka, lavandins), L. stoechas (Spanish Lavender) and L. dentata (French Lavender). 

And, there are certainly other varieties and cultivars out there as well. This will be the time for your first major decision – where do you want to grow your plant, indoors or outside. Your second question is do you have the proper spot to plant it. Finally, just how much of an attentive gardener are you?

Lavender Window Sill
Photo courtesy gardeningknowhow.com

For those who want an indoor plant which can bloom for a great part of year, L. dentata ‘Goodwin Creek Gray’ is a good choice.

This tender to half-hardy variety has light gray, fern-like leaves which contrast nicely with its dark purple flowers. 

It is one of the best lavenders to grow in a container on a south- or west-facing the window sill. It can be brought outdoors from late Spring to early Autumn.

Lavender Otto Quast
Photo courtesy ecgrowers.com

If you want to add a different style of flower to your lavender beds, Spanish Lavender will fill the bill. 

With their short, petal-topped blooms, they will add a nice bit of texture to your beds. 

As a half-hardy variety, they will do its best when planted on the south-side of the house.

Lavender of Provence
Photo courtesy natureandgarden.com

For the epicureans and scent seekers among you, take a look at the hybrids. L. x intermedia ‘Grosso’ is among the most fragrant of the varieties. 

Its dark purple blooms are used for making perfumes, sachets and filling a room with a pleasant aroma. One of the tallest of the group at, 36”, is L. x intermedia ‘Provence’ (pictured at left) and its light-lavender blue flowers are the quintessential lavender blooms you will see in the fields of southern France.

Finally, there are the other gray-foliaged, hardiest-of-their-kind lavenders, the English Lavender. 

The Old Guard stalwarts of this group are ‘Hidcote’ and ‘Munstead’. These vertically-challenged varieties will mature to 18” – 20” tall and slightly wider. 

Although shorter in stature than most of the others, they have an excellent fragrance and have a 2,000 year history in providing that quality to we discerning humans. They are also a top choice for low hedges and cut or dried flowers which come in shades of purple or white.

 

English lavender

By most reviews, they are also among the tastiest for cooking savories and sweets. The fact they rebloom in autumn is just another added benefit.

With their development history based in the Mediterranean basin, it makes sense that lavenders need as much Northwest sun as they can get. Coming from a rocky native stratum, lavenders are accustomed to a lean and slightly alkaline soil. (If you are uncertain about your soil’s pH, send a sample to the King Conservation District. The first five tests are free.) and good drainage.

Finally, while all of us try to be attentive gardeners with our plants, amending, irrigating, fertilizing, etc., most of these beneficial tasks are counter-intuitive to what lavender actual prefer. 

Being too good to your plant can be the kiss of death and reduce the scent of the blooms. Lavenders prefer lean soil, which means you don’t want to improve your clay soil with too much compost. Consider adding coarse sand, perlite or vermiculite to lighten the soil and improve the drainage. This one action can save your plants from water-logged root-rot in winter which is the primary cause of the untimely death of lavender. 

These plants are accustomed to a slightly alkaline soil of 6.5 – 7.0. If you have a low pH, add dolomite lime. (If you are uncertain about your soil’s pH, send a sample of the garden bed to the King Conservation District. The first five of your tests are free.)

Another water issue, first-year plants should be irrigated once a week to help their roots better establish. After that first year, other than irrigating once a month during the summer months, do not add water. The plants and your PUD water bill will thank you.

Lavender and Rocks
Photo courtesy backyardgardenlover.com

PIC-GRAVEL MULCH Finally, when it comes to adding a layer of mulch to suppress weeds and protect roots from undue heat or cold, consider your best mulch-of-choice to be a 2” layer of sand or white pebbles. 

These two materials improve drainage and will reflect the sun’s heat back up to the lavender.

Lavenders require little time and attention. Considering the year-round positive impacts they will have in your garden with their foliage, fragrant flowers and pollinator-friendly affinities, they will be welcomed new additions to your landscapes. 

Until next month, Happy Gardening all!

Clinics Alert - WSU Master Gardener Clinics across the county will be reopening again in May! Check the Master Gardener Foundation of King County website (mgfkc.org) for the days, times and locations. 

We’ll be happy to see you again! The email clinic (ask-a-mastergardener@live.com) which has been in operation during the pandemic service will also remain active during this time.

Contributing columnist, Bruce Bennett, is a WSU Master Gardener, lecturer and garden designer. If you have questions concerning this column, have a question to ask or want to suggest a topic for a future column, contact Bruce at gardenguy4u@gmail.com