Castilleja (Indian Paintbrush) in the Garden, Part 2

by Art Guppy

Art wrote several articles about Castilleja, which were published in two 2005 issues of the Alpine Garden Club of BC Bulletin and others in BEN (Botanical Electronic News).

If you have red, orange, or pink Castilleja in your garden, you can be sure of being visited by hummingbirds, and if you examine the individual flowers of these Castilleja, you will see they have evolved a perfect shape for pollination by hummingbirds. As the bird thrusts its beak into the corolla tube, the feathers of its forehead brush the pollen-laden anthers, and when it later visits another flower, the pollen-covered feathers brush against the stigma which protrudes from the tip of the galea (beak-like upper lip of the flower). Castilleja species that are yellow (including C. levisecta), greenish, or purple generally are pollinated by bees, and have nectar available at the base of a short corolla tube within reach of bees. A few paintbrush species are probably moth-pollinated, and I would guess that the yellow form of C. hispida is in this group, for its long corolla tube would exclude bees and its colour would not attract hummingbirds.

There are several ways you can grow Castilleja from seed. If you have lots of seed, you can scatter it liberally about in your garden and hope for results. A much better way is to first plant a few young host plants with roots close to the surface, and then sprinkle the seeds near them. Fall or early winter would be the best time as the seeds require a cool period while moist before they will germinate.

If you have only a few seeds and want to be fairly sure of success, I recommend the following method. You will need some clean, moist, sterilized sand and a little sterilized dry sand. A suitable container is the 500-grarn size of yogurt or cottage cheese container. For a cover use a piece of thin plastic such as can be cut from a plastic bag. Thin plastic allows air to pass through but holds moisture in.

Place about 2 cm. of moist sand in the container and level it.  Sprinkle the seeds thinly over the surface and add just enough dry sand to not quite cover the seeds. The dry sand will quickly absorb moisture from the moist sand.  Cover the container and place it in your fridge. Generally the seeds will germinate in the fridge within 2 to 5 weeks, but if after that time nothing has happened, you could try bringing the container out into a warm room. After the seedlings have had a few days to develop roots, they are ready to transplant.

Now we must go back in time to about when you first placed the seeds in the fridge. About then you will need to have potted some young host plants with roots close to the surface. The potted hosts can be sunk in the garden until needed. Then submerge the pots in water for about 24 hours to drown any unwelcome guests. Allow the pots to drain and you are ready to plant the tiny Castilleja plants. Dig little hollows close to host roots then use a spoon to scoop out moist sand holding the tiny seedlings. Carefully place the seedlings, still in the sand, in the hollows close to the host roots. Add dry sand to fill any crevices and immediately moisten the sand so the seedlings are settled in place. You can plant several seedlings for each host.

Place the pot with its cargo of plants in a clear plastic bag and draw the bag closed, tent-like, above the plants. A few little stakes may be needed to keep the bag off the plants. Use a twist-tie to hold the bag closed. Place the pot in a window of a moderately warm room where it will get plenty of light but no direct sun.

When the Castilleja seedlings are established and growing, gradually open the plastic bag and move the pot to a location with some sun. After they have grown into strong young plants, you can thin them to 3 or 4 to a pot. Finally transfer the Castilleja and their host, without separating them, to a suitable place in the garden.  Keep the soil moist.

Quite commonly the young Castilleja will keep growing through their first summer, and likely will flower by September. During their second and subsequent years Castilleja generally bloom in late spring. C. hispida and C. levisecta can be allowed to become fairly dry after flowering and will go semi-dormant, but C. miniata should be kept at least a little moist. Try to keep the paint brush and host in balance by cutting back the one that grows too well.

Many species of Castilleja, including the ones discussed here, can be propagated from cuttings taken in late winter, but you will need to be observant to find the suitable material. By late summer most Castilleja plants are semi-dormant except for ripening seed capsules.  Then, with the arrival of fall rains, the plants begin to produce numerous tiny green shoots near ground level. These shoots grow very slowly during the winter (and during that time are very susceptible to attacks by slugs) but by late February the rate of growth increases.  As soon as the shoots are large enough to handle — probably in late February or early March — a few can be collected as cuttings. The plants produce such a redundancy of shoots that unless slugs have been there ahead of you, the few you collect will not be missed by the plant. Do not wait too long before collecting the shoots or they will become attenuated and inclined to wilt.

Having collected your cuttings, dig small holes close to the roots of host plants, and fill the holes with sand or sandy soil. Into the sand or soil insert the cuttings and water them in place. To maintain a moist atmosphere around the cuttings, improvise cloches to cover them. I use the clear plastic containers such as many things from doughnuts to doorknobs are sold in. Cut a hole in each cloche near the top for ventilation. Shelter them from direct sun. After the cuttings are growing, gradually raise and then remove the cloches.

Propagating Castilleja from cuttings is an especially useful method if you have a colour form or a hybrid you wish to have more of. There are indications that some Castilleja species, including C. levisecta, have rather short lives and may live only 4 or 5 years.

I perhaps should add that I have grown Castilleja because they are interesting plants , but I have not specialized in them and at present have only a few.

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About Art Guppy

Art spent over 70 years studying and writing about native plants of the Pacific Northwest from BC to California, especially the genus Erythronium and related plants. This site is a compilation of his work for the benefit of naturalists everywhere.
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