Do you know Polygonella?

We have been playing around with the genus Polygonella since 2000, but have still only grown 3 of the 11 US species so far. We are fascinated why these native, highly drought-tolerant members of the buckwheat (Polygonaceae) family aren’t more widely grown.

The common name of jointweed, probably is the biggest factor in their lack of popularity, but then botanist aren’t usually known for their marketing prowess. The plants do have joints, but they are far from being weeds. Polygonellas look like miniature subshrubs of obscure green joints until they burst into flower with hundreds of tufts of small white flowers, that are covered by all kinds of bees.

Below is a current photo of our 4-year-old clump of Polygonella americana. In my humble opinion, honeybee keepers should be planting these everywhere, since they flower during what is known as the “nectar dearth” season, starting here in June. For us, Polygonella americana flowers from June until October. Our plant is growing the un-irrigated crevice garden in a Permatill dominant soil, since great drainage is essential.

Polygonella americana

Globs of Globularia

Globularia is a genus of small, rock garden-sized plants in the Plantaginaceae family, with a native distribution centered around Mediterranean Europe. I admired these during our 2012 Balkan expedition, but it wasn’t until we constructed our crevice garden empire, that we really began to have much success with the dryland plants in our wet, humid summer climate.

We’ve now tried 15 of the 22 known globularia species, and have only lost two of those outright. While globularias are usually grown for their puffy blue, ball-shaped flowers in spring, we love species like Globularia repens for its habit as a slow-growing, dense groundcover. The key to our success is a soil mix of 50% Permatill, which is a lava-like popped slate. Hardiness Zone 4b-8a.

Globularia repens

Getting a Handle on Handelia

Here’s another of those plants that virtually no one has either grown or even knows about. Handelia trichophylla is a little-known monotypic member of the aster family (Asteraceae). Not only does it have hairy, silver foliage, which usually spells certain death in our summers, but it hails from the “stans”, which include the low rainfall countries of Afghanistan, Kazakhstan, Kirgizstan, Pakistan, Tadzhikistan, Turkmenistan, Uzbekistan, and Xinjiang. Our particular plant is from a seed collection in Tadzhikistan.

We would not typically expect anything native to the “stans” to survive in the hot, humid Southeastern US, but this is why we experiment, and why we create unique habitats and microclimates in our garden. In this case, Handelia has thrived for four years in our crevice garden, where it grows in a soil mix of 50% Permatill.

Handelia trichophylla

Carolina Bluebonnets

Looking lovely now at JLBG are two species of Texas blue bonnets; Lupinus subcarnosus (top) and Lupinus texensis ‘Abbott PInk’ (bottom). Both are winter annual species that dot the Texas highways in spring. These are on of a very short list of annuals that we allow in the garden.

These have returned for us for 20 years. The key is to plant the seed in a dry area, especially one that is mixed with Permatill. The seed germinates in late fall, and the plants flower the following spring.

Lupinus subcarnosus
Lupinus texensis ‘Abbott Pink’

December Daphnes

I’ve posted about daphnes a couple of times this year, but can’t help post again now that we’re in December and still have two daphnes in full flower, despite two nights at 25 degrees F.

The top is Daphne collina from Southern Italy, and the bottom is Daphne x napolitana ‘Bramdream’…a hybrid of Daphne collina x Daphne cneorum var. pygmaea. These are growing in our dry crevice garden in a soil mix of 50% Permatill gravel. It seems obvious that the Daphne collina is the source of the continuous bloom. Winter hardiness is Zone 6a-8b (top), and Zone 5-8b (bottom).

Daphnes in the crevice garden
Daphne collina
Daphne x napolitana 'Bramdream' in the rock garden
Daphne x napolitana ‘Bramdream’

Feel the Berm

Just over a year ago, we built a new berm garden, adjacent to our Open House welcome tent. Here is that garden today. The soil is composed of 50% Permatill (slate gravel), 25% compost, and 25% native soil). This is in an unirrigated section of the garden. Like all garden spaces at JLBG, no commercial fertilizers are ever allowed. The exceptional drainage and high nutrient content from the compost and Permatill result in an amazing growth rate.