I've touched on this subject elsewhere on the forum, but given how many parts of the country are seemingly having more drought problems, I thought that it might be nice to have a separate thread listing drought (and preferably, critter) tolerant companion plants for the Iris garden.
The ideal companion plant should:
1. At least be drought tolerant (it does not have to be absolutely xeric, like a succulent or cactus). Water at least once a week, possibly twice (especially in the summer).
2. Have a bloom time (or if no blooms, then at least have interesting foliage) that at a minimum overlaps with part of the iris season. Bonus points for garden interest (blooms or foliage) outside the iris season, especially for long-standing interest. Bonus points for foliage with a different habit (i.e. not long and narrow).
3. Preferably be resistant to whatever critters are native to your area.
4. Bonus points, if suitable only for a narrow climate zone, if the plant is relatively easy to propagate overwinter under lights. (Obviously Zone 8-9 plants won't be suitable for most areas of the country, and most likely you aren't going to overwinter larger tender specimens (such as shrubs) indoors.)
Below I am listing a few of my plants; please join in, and for the benefit of others, list the Zone range for the plant.
1.
Tulbaghia violacea aka Society Garlic generally Zone 7a-11 but check the specific cultivar
Society garlics flower in a narrow color range of lavender, pinkish lavender, or (hard to find) white, but they start bloom with the TB irises and can bloom into early autumn. Named cultivars can vary from the generic species wrt size, bloom color, and vigor. In my experience, the generic species (with lavender flowers) can be particularly vigorous and may have taller bloom stalks than some of the named cultivars. Variegated society garlics tend to be scant bloomers and are therefore more suitable for foliage effect, but the foliage can sometimes revert back to all green.
In my experience, the society garlics are ignored by gophers, rabbits, and deer.
TB 'Royalty Remembered' with society garlic 'Ashanti'
TB 'Arctic Express' with rose "Flower Carpet White' in the foreground, and society garlic 'Pearl' in the background
2.
Pelargoniums generally Zone 10-11, but will survive most Zone 9 winters
Colors come in various shades of pink, red, salmon, purplish, and white. There are lots of "series" of pelargoniums available at your local garden center (where they are generally referred to as "geraniums"), some of which have variegated foliage. But unless you are a connoisseur, there is no need to have the latest/greatest/finest, or even a named variety. (I have about 7 or 8 pellies in my garden, but my favorite is a NOID which I picked out at a garden center for its highly attractive pink color. I call it my "Back Door Pink".)
The plusses (beyond drought tolerance) are a long season of bloom, contrasting foliage shape, and general critter resistance. The downside is that these are not cold weather tolerant. In most years, in my Zone 9 garden, there might be a little frost damage to my pellies but that's it. (However, there have been one or two winters where all the unprotected pellies outright died.)
Pellies are cheap enough that a plant or few are affordable if you want to start anew each year, but given the relative ease of propagation from stem cuttings, why bother? Just take cuttings before frost and overwinter indoors. (I recall reading somewhere where someone took their pellies out of their pots and hung them up somewhere overwinter. I can't imagine how that works.
)
(Sadly, while I do have one pellie in the ground (as opposed to a pot), near where irises are growing, I couldn't find any iris shots with it in it.)
3.
Iberis sempervirens aka Candytuft; generally Zone 3-9b
Surprisingly, this is considered a drought tolerant plant.
In my garden
Iberis overlaps in bloom with the SDBs and the early TBs, but it is mostly valuable for white flowers in late winter and early spring, when not much else is going on in the garden. The evergreen foliage is low and mounding, which is a pleasing contrast to iris foliage, and provides some structure to the garden throughout the year. It can be used as an edging plant, or planted to grow to cover a wider area. Thus far it has proven to be gopher, rabbit, and deer resistant.
This is another plant where you have a choice of generic species, or NOIDs, or named cultivars. I have the species/NOIDs, and I also grow and can recommend 'Alexander's White' and 'Autumn Beauty'.
Iberis 'Alexander's White' with TB 'Emma's Laughter'
4.
Salvia Depending on the species, may be Zone 6 or Zone 8 to 10; check conditions for your plant
Salvias are drought tolerant, have a long season of bloom (overlapping with at least the TB irises), and are resistant to gophers and deer, but (depending on the species) possibly not rabbits. As a bonus, they are a natural nectar source for hummingbirds.
The only downside (unless your garden is too wet or too cold) is that as a shrub, they can grow somewhat sizeable, so they are something of a structural or background plant. (In cold winter gardens they can be grown as annuals, in which case they may not grow so large.)
In my garden, the white salvia 'Heatwave Glimmer', and the red-and-white flowered salvia 'Hot Lips', can be in bloom with the TB irises. The former is in the Moon Garden and while there is a white iris nearby, I haven't any pictures of the two together.
5.
Euryops Various species, evergreen shrub, possibly Zones 8-11
There are various species of this shrub, but the common features are drought tolerance, yellow daisy-like flowers, and resistance to gophers, rabbits, and deer. Suitable for a structure or background plant.
I grow three plants of
Euryops chrysanthemoides 'Sonnenschein' as a several foot hedge. As they bloom in winter, they provide winter color interest, and their yellow flowers overlap at least with the early to midseason TB irises.
'Euryops chrysanthemoides 'Sonnenschein' with TB 'Sara's Beauty
The following two plants are not presently close enough to my irises to really be called companions, but in a deliberate planting, they arguably could be.
6.
Pallenis maritima subsp. maritima Zone 9? Mediterranean
Aka
Asteriscus maritimus, 'Gold Coin', 'Gold Dollar', and "Mediterranean Beach Daisy", there is a paucity of information on this plant. While it can serve as a companion plant, of sorts, it is not ideal as such because bloom is limited to spring, and the foliage is not all that interesting when the plant is not in bloom. This is also a plant that (at a guess) would grow only in a narrow range of conditions (many CA gardens).
This plant was introduced into my garden via a landscaper, and a few plants have persisted (it can also volunteer) through many years in heavy clay soil jam-packed with redwood roots. The green-grey evergreen foliage has a low mounding habit. The plant is covered with golden yellow flowers, and overlaps in bloom time with the SDBs and early TBs. Gopher, rabbit, and deer resistant.
I imagine that this could pair well with white, yellow, or purple irises.
7.
Erigeron karvinskianus Santa Barbara Daisy Zone 6b to at least 9
Spring (also summer?) blooming with small white flowers which fade to pink. In my garden, this is one tough plant. It is drought tolerant, seems to thrive on poor soil, and while it is arguably a weed (it has a tendency to volunteer), the flowers are charming enough that you don't really mind. Resistant to every critter here.
While I didn't plant this next to any irises, it has self sown itself (from the front yard to the back
) and planted itself next to the SDB 'Blue Oasis'. The latter hasn't bloomed (yet?) this spring, so no pictures.
I think this could pair well with pink irises.
All of the above companion plants were chosen with bearded irises in mind, but the Pacific Coast Irises are also drought tolerant, and display nicely with companions of their own.
In my garden, rosemary (Zone 8a - at least 9) and
Lavandula stoechas (Zone 7b-10b) have self sown and naturalized in one area where I grow PCIs, and bloom times overlap. (The
Lavandula stoechas also overlaps bloom time with the early TBs.)
In a separate, shadier area of my garden,
Pulmonaria may bloom with early PCIs, and provide a contrasting foliage habit. While they prefer moist soil, the lungworts can tolerate some amount of drought.
Pulmonaria (possibly 'Trevi Fountain') with the unregistered PCI 'Silver Moon'
