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| Blue-eyed grass (Sisyrinchium bellum) - a small native Iris. Mother Nature's Backyard, Gardena CA. |
Much
can be said for garden bulbs. They come
up year after year, a welcome spot of color in the spring or summer
garden. They spread and naturalize,
turning a small initial investment into something spectacular (if you’re patient).
Many bulbs are relatively easy to grow. And there’s something enchanting about a
perennial that dies back to the ground, then re-appears, as if by magic, in the
spring.
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| Swath of Goldenstars (Bloomeria crocea) Rancho Santa Ana Botanic Garden |
Many
California gardeners don’t realize that California is home to over 200 species
of native bulbs, corms and rhizomatous perennials. While many native bulbs can be found in
coastal areas and in the mountains and foothills, most parts of California –
even the deserts – are home to at least a few species. Happily, more species are showing up in local
gardens each year.
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| Example of California native true bulb: Calachortus species |
The
perennials known as ‘garden bulbs’ actually belong to three different groups:
those with true bulbs, those from corms and those from reproductive
rhizomes. True bulbs are short, underground stems, complete with fleshy leaf
scales and an embryonic plant. The
energy for next year’s growth is stored in the leaf scales; the plant survives
harsh environmental conditions (cold and/or dry) in a dormant state. Onions are
a good example of true bulbs. The rings
you see when you cut an onion are the leaf scales; the embryonic plant is in
the center.
True
bulbs die back to the same bulb each year.
They reproduce by seed and by producing offsets (bulblets or bulbils)
that are usually clustered at the base of the mother bulb. True bulbs are among the most beloved garden
treasures; some – like the onions - are also important edibles. Common examples of plants from true bulbs are
Amaryllis, Narcissus/Daffodil, Allium (Onions), Lily and Tulip. Additional genera from California include: Calochortus (mariposa lily), Camassia (camas lily), Chlorogalum (soap lily) and Fritillaria (fritillary).
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| Example of California native corm: Dichelostemma |
Perennials
from corms also store energy in an
underground stem base during the dormant season. But you won’t find any rings
when you cut open a corm – they’re solid!
The corm is truly a food storage device, and corm-forming perennials
produce a new one each year – one on top of the other. You will sometimes see the remnants of many
old, used-up corms on an old plant.
Like
the true bulbs, corm-forming perennials reproduce both by seed and by producing
offsets, called ‘cormels’ (tiny corms).
Many plants from corms are popular garden perennials. Among the better known are the so-called
‘Autumn Bulbs’: Gladiolus, Crocus, Crocosmia, Colchicum, Freesia and
Watsonia. Several important food plants
– including plantain/banana and taro – are corms. California is home to additional
corm-producing genera including Bloomeria
(goldenstar), Brodiaea, Dichelostema (wild hyacinth), Erythronium (fawn lily), Odontostomum (doll lily) and Triteleia.
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| California native rhizome: Sisyrinchium |
True
bulbs and corms can be kept cool and dry, then shipped dormant to your
door. Not so the plants from reproductive rhizomes. These are almost always purchased as young
plants, since the actual rhizomes have a short shelf-life. Rhizomes
are horizontal, underground stems; the reproductive/dormancy types are
thickened for food storage. A good
example is the Bearded Iris. The Douglas
iris (sometimes called ‘Pacifica Iris’) and the Sisyrinchium species (Blue-eyed grass; Yellow-eyed grass) and Epipactis (stream orchids) are good
examples of natives from rhizomes.
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| Bloom time is coordinated with pollinators: Umber Skipper on Wild hyacinth (AKA Bluedicks) (Dichelostemma capitatum) |
When do native bulbs, corms and
rhizomes bloom?
Because
we live in a mediterranean climate, many California species bloom in spring or
early summer. That allows them to
bloom, set seeds and store energy before the long dry season commences in
earnest. But there are some ‘bulb’ species
that bloom very early (February) and other which are later (July or even
later). In general, those from Northern
California and from higher elevations tend to bloom later than those native to the
S. California lowlands and deserts.
Garden
bulbs begin to grow, flower and set seeds partly in reaction to environmental
cues. California species often begin
growing when the ground becomes moist in winter or early spring. Others need warmer temperatures, or a certain
length of cold exposure, to commence growing or flowering.
Because
environmental conditions vary from year to year, the timing of bloom can only
be approximate. Additional factors which
may influence timing in individual gardens are sun exposure and whether plants
are grown in pots or in the ground. But
here are some rules of thumb for common native bulbs, corms and rhizomes in
lower elevation S. California gardens.
Bloom time | Genera |
Early (Feb-Mar) | Dichelostema/Wild Hyacinth (especially S. California ones) Allium (S. California lower elevation types) Sisyrinchium begins Early Calochortus (desert and S. California species) |
Mid-Spring (Apr-May) | Allium (N. Coastal and higher elevation onions) Bloomeria/Goldenstars Calochortus Camassia/Camas lilies Chlorogalum/Soap lilies Iris (native ‘Pacifica’ or Douglas Iris) Sisyrinchium Tritelias |
Later (June or later) | Brodieae Epipactis/Stream orchids Lilies Tritelias (if not earlier) |
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| Meadow onion (Allium unifolium) |
When should I plant native garden
bulbs?
Native
bulbs and corms should be planted as soon as the ground softens up in late
fall/early winter. Natives from
rhizomes are also best planted during to cool, wet season. Here is a typical calendar for managing
native ‘garden bulbs’:
Summer
– order bulbs or seeds from reputable sources (see below)
Fall
– bulbs shipped/rhizomatous plants purchased
Early winter – plant bulbs/corms; plant out
rhizomatous plants.
Winter/spring – many native ‘bulbs’ emerge, grow
and flower. Give dose of ½ strength fertilizer to bulbs grown in pots in winter.
Spring/summer – many native ‘bulbs’ set seed;
foliage dies back. Begin to withhold water
as foliage dies back or flowering commences (whichever comes first). Collect or scatter dry seeds. Cut back dry flower stalks; let leaves remain attached if possible.
Summer/fall
– native bulbs/corms/rhizomes are dormant
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| Many California native bulbs and corms do well in pots. |
Can I grow native garden bulbs in
pots?
Yes,
in fact that’s a good way to use native ‘bulbs’ to best advantage. Pots can be ‘retired for the season’ during
the dormant period. And pots are one of
the best ways to multiply rare bulbs and corms, prior to planting out in the
garden.
The
best containers for native bulbs are at least 8 inches deep and 12 inches in
diameter. This will allow space for
bulbs to increase for 3-4 years without replanting. We prefer unglazed clay pots, but most pots
will do, as long as bulbs can be summer dry.
One
way to feature bulbs for seasonal color is to use the old cache pot trick;
plant the bulbs in an inner pot, which can then be removed and replaced as the
season requires.
We
let our potted bulbs bloom and set seed, collect the seed (or scatter in the
pot), then move the pot to a cool, dry place until late fall. At that time we add a layer of fresh potting
soil, expose the pots to the winter rains, and away we go. There’s no need to remove the bulbs from the
pot each year.
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| Douglas Iris - Madrona Marsh Nature Center Torrance CA |
Do I need to dig up native garden
bulbs each year?
No. The reliable ‘bulbs’ (recommend below) do
fine (in a pot or in the ground) for at least 3-4 years without digging them
up. If flowers become less profuse – or
pots appear crowded – then you will
need to dig up ‘bulbs’ and replant. This is often more of an issue with
pot-grown plants – but those in the ground may also become over-crowded. Native Californians harvested most of the
edible bulbs and corms every third year, keeping wild resources productive. That’s
a good rule of thumb for the home gardener as well.
Pot-grown
bulbs and corms can be dug up anytime from late summer through fall. We just dump the whole pot out, then sift through
the potting soil to find ‘bulbs’ of all sizes.
We repot the largest in fresh potting soil and pot up the smaller ones
in new pots (you can place the smaller ones about ½ inch apart).
If
growing the rhizomatous species, divide the rhizomes as you would a bearded
Iris. You don’t need to be too gentle -
just be sure that there’s a new shoot on each piece. Smaller bulbs and corms
may take several years to get to a size where they will bloom. Divided rhizomes usually bloom the first or
second year.
Bulbs,
corms and rhizomes grown in the ground are a bit more of a challenge. If the dry ground is hard, you may have to
wait for the first good rain to soften the soil. Then get out, dig up and replant the ‘bulbs’
to give them room to thrive.
What’s the trick to watering native
garden bulbs?
Like
all perennials, native bulbs, corms and rhizomes need adequate winter and
spring moisture. If we have a dry winter/spring,
you’ll need to supplement after the ‘bulbs’ begin to grow and until either: 1)
the leaves start to yellow, or; 2) flowering commences. After that, plants need
less water. Taper off water as the plants
flower, the flowers wilt and the seeds develop.
Being
from a mediterranean climate, most California native bulbs, corms and rhizomes
need a dry, dormant period from summer through fall. That being said, plants from climates that
get a little summer rain – or grow near lakes and streams - are more tolerant
of summer water than those from summer-dry Southern California.
Native
‘bulbs’ from Northern California, as well as those that experience summer
monsoons (including those from the Sonoran desert, Southern San Diego County
and the local mountains) will accept occasional summer water. Emphasis is on ‘occasional’ – native bulbs
need a dry period and are susceptible to rotting if over-watered.
The
best strategy is to either plant the more tolerant species – or plant local
species in areas that can be kept summer dry (or nearly so). If you don’t have a summer-dry area, grow the
natives in a pot.
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| Ripe seed ready for scattering or collecting. |
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| Blue-eyed grass (Sisyrinchium bellum) from seed. |
Can I grow native garden bulbs from
seed?
Yes. In fact many are easy to grow from fresh
seed. If you want to naturalize, just
scatter seeds in the garden (or into the pot with the bulbs) and they’ll take
care of themselves. You can also collect
the dry seeds, store in a cool dry place (we put them in envelopes in a cool
room), and plant them in the late fall.
Stored
seeds can be started in pots in late fall or winter. Nearly fill a pot with potting medium (not
garden soil), scatter fresh seeds in the prepared pot, cover lightly with a
little extra potting soil, water in and place in a place where pots are watered
by rains. A partly shady place is best
and you may need to supplement the rains.
Tiny seedlings look like grass (see above) and are very susceptible to
drying out.
If
using purchased seed (or seeds from colder climates) you may need to pre-treat
the seeds in S. California. Follow the
grower’s directions or give the seeds 4-6 weeks cool moist treatment (we use a
moist coffee filter, in an open plastic bag in the refrigerator).
We
let our pots of small seedlings slowly dry out mid-spring, place pots in a cool
dry place for summer/fall, then bring them out again in winter. It will take plants grown from seed 3-4 years
to reach flowering size. We recommend
repotting the bulbs in the fall after the third growing season.
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| In Mother Nature's Backyard we let bulbs naturalize from seed. |
Do I need to dig or amend the soil
prior to planting native garden bulbs?
Nope. If planting them in the ground, all you need
is a hole as wide as the bulb and 3 times as deep (or at least 3 inches). The reliable native bulbs don’t need lots of
amendments or babying – that’s one of the joys of gardening with them.
If
growing the native bulbs in pots, just add a layer (1-2 inches) of fresh
potting soil to the top of the pot each fall, unless you’re dividing and
replanting. If replanting, start out
with fresh potting soil.
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| Peninsular onion (Allium peninsulare) - showy California native bulb |
Where can I purchase native garden
bulbs?
Fortunately,
some of the best sources for bulbs, corms and seeds are mail order. Be sure to get your order in early (summer)
before some of the choicest species are sold out. Here are our recommended sources:
1. Teleos Rare Bulbs – best source for CA natives (including rare) – mail order
- Theodore Payne Foundation – some native bulbs/corms as plants or
propagules - Rancho Santa Ana Botanic Garden - some native bulbs/corms as plants or propagules
- Project SOUND – CSUDH – limited number of bulbs/corms and rhizome
plants in fall - Larner Seeds – CA native plant seed; mail order
- Seedhunt –
CA native plant seed; mail order - Fraser’s Thimble Farms – native and non-native; mail order
- John Scheepers/Van Engelen Bulbs – some natives, cultivars; mail order
- Hedgerow Farms – some native bulbs; mail order
- Alplains –
native seeds; mail order
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| Goldenstars (Bloomeria crocea) are lovely and easy to grow |
What species do you recommend for the
beginning bulb gardener?
Some
native bulbs, corms and rhizomes are easier to grow than others. We recommend the easy species to the
beginning gardener. They are also the
ones we rely on for dependable color, year after year, in our own gardens. Here are our recommendations for lower
elevation S. California gardens.
Scientific Name | Common Name | Flower/ season | Light* | SummerWater** | Bulb/seed Sources+ |
Allium dichlamydeum | Coastal Onion | Magenta/Sp | FS/PS | 1 | 1, 3, 4, 7 |
Allium haematochiton | Red-skin Onion | White-pink/ Sp | FS/PS | 1 | 1, 2, 3, 7, 10 |
Allium peninsulare | Mexicali Onion | Magenta/ Sp | FS/PS | 1 | 1, 8, 10 |
Allium unifolium | Meadow Onion | Magenta/ Sp | FS/PS | 1-2 | 1, 2, 3, 4, 6, 8 |
Bloomeria crocea | Golden Stars | Yellow/Sp | FS/PS | 1 | 2, 3 |
Brodiaea elegans | Harvest Brodiaea | Violet/Sp | FS/PS | 1 | 1, 3, 5, 6 |
Chlorogalum pomeridianum | Wavyleaf Soap Plant | White/Su | FS/PS | 1-2 | 1, 2, 5, 6 |
Dichelostemma capitatum | Blue Dicks/Wild Hyacinth | Blue/Sp | FS/PS | 1 | 1, 2, 4, 5, 6 |
Dichelostemma ida-maia | Firecracker Flower | Red-white/ Sp | PS best | 1 | 1, 3, 8 |
Dichelostemma multiflorum | Manyflowered Brodiaea | Violet-pink/ Sp | FS | 1 | 1, 2, 3 |
Iris douglasiana | Douglas iris | Purple/Sp | PS | 1 to 2 | 2, 3, 4, 5 |
Lilium pardalinum | Leopard Lily | Orange/Sp-Su | PS | 2-3 to 3 | 2, 3, 7 |
Lilium washingtonianum | Washington Lily | White/Sp-Su | PS | 1-2 to 2 | 9 |
Sisyrinchium bellum | Western Blue-eyed Grass | Purple/ Sp | FS/PS | 1-2 to 2-3 | 1, 2, 3, 4 |
Triteleia hyacinthina | White Hyacinth (Brodiaea) | White/Sp | FS/PS | 1 or 1-2 | 1, 3, 5, 7 |
Tritelia laxa including ‘Queen Fabiola’ | Ithuriel’s Spear | Purple/Sp | FS/PS | 1 | 1, 3, 5, 6, 7, 8 |
*light: FS=full sun
PS=part-shade FS=full shade
**summer water: 1=none; 2=occasional; 3=regular water
(taper off after blooming/setting seeds for all)
+ see bulb and seed sources above; numbers correspond to
the list (e.g. 1+Teleos Rare Bulbs, etc.)
Want to learn more?
Here are
links to more information on our recommended bulbs, corms and rhizomes:
Scientific Name | Common Name | More information |
Allium dichlamydeum | Coastal Onion | |
Allium haematochiton | Red-skin Onion | |
Allium peninsulare | Mexicali Onion | |
Allium unifolium | Meadow Onion | |
Bloomeria crocea | Golden Stars | |
Brodiaea elegans | Harvest Brodiaea | |
Chlorogalum pomeridianum | Wavyleaf Soap Plant | |
Dichelostemma capitatum | Blue Dicks/ Wild Hyacinth | |
Dichelostemma ida-maia | Firecracker Flower | |
Dichelostemma multiflorum | Manyflower Brodiaea | |
Iris douglasiana | Douglas iris | |
Lilium pardalinum | Leopard Lily | |
Lilium washingtonianum | Washington Lily | |
Sisyrinchium bellum | Western Blue-eyed Grass | |
Triteleia hyacinthina | White Hyacinth (Brodiaea) | |
Tritelia laxa including ‘Queen Fabiola’ | Ithuriel’s Spear |
Talk on native garden bulbs (including most of the ‘recommended’
species): http://www.slideshare.net/cvadheim/native-bulbs-for-california-gardens-2017
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| Tiger Swallowtail on Wild hyacinth (Dichelostemma capitatum) Mother Nature's Backyard |
We
welcome your comments (below). You can
also send your questions to: mothernaturesbackyard10@gmail.com
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