Stipa gigantea (Golden Oats)

Stipa gigantea, commonly known as Golden oats or  Giant Feather grass, is a large perennial evergreen grass with long, slender, arching green leaves that form a dense tussock.

During spring and summer, tall flower stalks rise from the foliage clump, adorned with dangling spikelets of golden oat-like flowers.

This is one of the most impressive grasses native to the Mediterranean basin, specifically to Spain, Portugal and Morocco

Stipa gigantea plant (Golden Oats, Giant Feather grass)

Quick Overview

TYPE

Type herbaceous

HEIGHT & WIDTH

stipa gigantea height and width

BLOOM TIME

stipa gigantea bloom time

SUNLIGHT

full sun

HARDINESS

hardiness (-12ºC / 10º F)

DROUGHT TOLERANCE

drought tolerance aprox 5 months

ORIGIN

origin mediterranean basin

Golden Oats Scientific name

  • Botanical name:  Stipa gigantea (STY-puh jy-GAN-tee-uh)
  • Family: Poaceae (po-AY-see-eye)
  • Common name: Golden Oats, Giant Feather grass, Giant Oat Grass
  • Synonyms: Celtica gigantea, Macrochloa gigantea
NameMeaning
StipaLatin word meaning stalk or straw.
giganteaLatin word meaning giant, which describes the large size of this plant

How to identify Stipa gigantea

Stipa gigantea plant (Golden Oats, Giant Feather grass)

Plant

Stipa gigantea is a large perennial grass that forms a dense clump of long, narrow leaves which remain green all year round.

It slowly grows around the outside, forming a large tussock. Eventually, the centre will die out, which indicates that it is time to divide and replant it.

During the spring and summer months, tall stems standing straight like poles emerge from the foliage. These stems carry feathery clusters of pendulous golden spikelets resembling oats. This is why it is commonly known as Golden oats or Giant feather grass.

Stipa gigantea is one of the largest Mediterranean grasses. Its foliage is 50 to 70 cm (1.6 to 2.3 ft ) high, and the flower stem is around 2m (6.5 ft) long. The width is 1.25m (4 ft).

Stipa gigantea stem (Golden Oats, Giant Feather grass)

Stem

Stipa gigantea has tall, round and hollow flower stems that emerge from the foliage during spring and summer. They’re smooth, green, and don’t have any hairs.

Along the stem, 3 to 5 leaves wrap around it, and at the top, a panicle of drooping spikelets remains until winter, keeping the garden interesting all year long.

Stipa gigantea leaf (Golden Oats, Giant Feather grass)

Leaf

The leaves are long, very narrow, leathery, and green. They are rolled up at the edges, pointed at the tip, smooth on the bottom, and rough on the top. Parallel veins run along the whole length and taper at the tip.

There are also 3 to 5 leaves further up the stem, similar to the ones at the bottom, with a slightly bigger ligule ( a thin outgrowth at the junction of the leaf ) and usually longer than the basal leaves. Sometimes, the uppermost leaf partially covers the flower cluster at the top.

The length of the leaf is between 30 and 85cm (1 to 2.7 ft).

Stipa gigantea flower (Golden Oats, Giant Feather grass)

Flower

The inflorescence is a panicle 25 to 50 cm (10 to 20 inches) long with a relaxed oval outline. The spikelets are spaced apart, giving it a light and airy appearance.

The spikelets, which are mostly pendulous and have a long awn, are attached to a smooth stem. Sometimes, with a tuft of hairs where the branches meet the stem. There are usually 2 to 3 branches in each bunch. Each individual spikelet is around 2 to 3 cm (0.8 to 1.2 inches) long

When the spikelets mature, they open, and we can easily observe the following parts.

The glumes (external bracts surrounding the spikelet) are long and narrow, shaped like a lance. They are translucent with a green or yellowish tint.

The lemma (internal bract protecting the floret) is papery and hairy, shaped like a spindle (wide in the middle and tapers at both ends).

The palea (internal bract protecting the floret) is lance-shaped and has two little teeth at the top. It is translucent with hairs on the back and sticks very close to the floret.

When the florets are open, they release their pollen and receive outside pollen. The dangling anther moves with the wind, releasing its pollen, while the feathery stigma easily captures pollen in the air, which then reaches the ovary, developing the seed. 

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Stipa gigantea Habitat

stipa gigantea backlit

Stipa gigantea is native to the Mediterranean basin and grows naturally in clearings of scrubland and forests of pine and holm oak.

It’s often found on rocky slopes and bases, usually on silica rock and sometimes on dolomite rocks. It can grow up to an elevation of 1350 meters (4430 feet).

Stipa gigantea Usage

Ornamental

Golden Oats grass is valued for its beauty. Its tall, elegant stature and graceful arching panicles of golden flowers that last throughout the year add softness, movement, and transparent height to the garden. The visual appeal, together with its low need for care, make it a popular choice for low-maintenance gardens.

It can be used in the landscape in the following ways:

  1. Focal point: Stipa gigantea’s tall, graceful stems and golden flower heads make it an excellent focal point in garden beds and borders. Its striking appearance draws the eye and adds visual interest to the landscape. When illuminated by early morning or late afternoon sunlight, it creates a dramatic effect, especially when it is backlit.
  2. Texture and movement: The fine, pendulous panicles of Golden oats bring texture and movement to garden designs. Their delicate, feather-like appearance offers a gentle contrast with surrounding plants and hard surfaces while also introducing movement with even the lightest breeze.
  3. Naturalistic plantings: It is often used in naturalistic or prairie-style plantings to create a sense of movement and wildness. Its native habitat and graceful form make it well-suited to informal garden designs.

Biodiversity

Stipa gigantea provides habitat and food sources for various wildlife species, including birds and insects, making it beneficial for promoting biodiversity in your garden.

Dried Flower Arrangements

The long-lasting seed heads of Golden Oats, can be picked in summer and used in floral arrangements, adding texture and interest to indoor decorations.

Artisanal products

The leaves of Stipa gigantea are used as raw materials for artisanal products such as baskets, carpets, and cushions.

The very thin leaves of this grass can be used for delicate and detailed art work.

Erosion Control

Stipa gigantea reprouting 3 months after wildfire

The dense clumps of Stipa gigantea can help stabilize soil on slopes and embankments, making it useful for erosion control in landscaping projects. 

It is especially useful for erosion control after wildfires because it sprouts very quickly after the first rainfall. In this picture, taken only three months after a devastating wildfire on my farm, you can see how lush this plant already looks.

How to care for Stipa gigantea

Cold exposure

This plant can tolerate frost and cold weather down to  -12ºC (10º F). But only if the soil is well drained. Cold, soggy soil can be fatal to it. 

While the plant is not yet established, you may want to add a thick layer of mulch around the plant’s base to protect the roots from cold temperatures. Using gravel mulch is preferable because organic mulch will stay humid and can cause the plant to rot.

Sun exposure

Golden Oats prefers full sun, but it can tolerate some light-dappled shade.

In extremely hot climates or areas with intense sunlight, it’s beneficial to shield plants from the harsh afternoon sun to avoid leaf damage. Offering partial shade during the hottest part of the day can shield the plant from excessive heat and strong sunlight.

Soil

Golden Oats grass thrives in poor, well-drained soils, particularly those with a gritty, rocky texture. It’s best to avoid planting it in damp locations, as it is not tolerant of soggy soil, which can increase the risk of root rot.

If your area tends to become waterlogged, you may need to keep the entire root ball above ground level and fill in with a raised mound of sandy soil, sloping gradually away from the plant’s base.

It prefers neutral PH soil but can tolerate mildly acidic to mildly alkaline soils

Avoid fertilizing the soil if you need the plant to remain robust and better equipped to handle extreme temperatures.

Watering

Golden Oats grass is very drought tolerant and can go for months without water once it is established (about 5 months of drought if the temperature is not too hot). 

Once established, it does not need watering. However, if there’s a long period without rain or very hot weather, you should give it a drink.

During its first year after planting, it’s essential to water the young plant regularly. Depending on the soil and the temperatures, you may need to water it once a week, every two weeks or every three weeks.

When you water the plant, make sure to give it plenty of water, allowing the soil to get a good soak. This way, the water can sink deep into the soil keeping it moist for longer periods.
To preserve the soil´s moisture, you should add mulch around the root area of the plant. The mulch should be gravel because organic mulch can lead to leaf rot.

Pruning

Evergreen grasses such as Stipa gigantea do not need to be cut back. 

Instead, you should remove the dried flower stems by the end of winter, which can be pulled off easily. 

After that, comb through the leaves with your fingers to remove the old leaves. This is important because if you leave the old leaves, the plant will be stunted because the new leaves cannot easily grow through them. So, try to clean out as much of the dead material as possible.

There are two ways to remove the old leaves:

  • With your hands – Gently remove the dead leaves, leaving the crown with only the fresh green leaves. Wear gloves for this task because the sharp grass blades can cut your fingers. 
  • With a rake – Alternatively, you can also rake it, which is a faster way of doing this. However, it may damage the new leaves, and you will not get such a nice result. It all depends on how much time you have to do this task. 

When to plant Stipa gigantea

The best season to plant is typically in the spring or autumn, but it will depend on your climate. You should avoid planting during periods of extreme temperatures.

If you have mild weather where you live, it’s best to plant in the autumn to give it time to develop the roots during the cooler months before the arrival of the hot summer. In case of very cold winters, it’s better to wait until spring when the risk of frost has passed and the soil is warmer. That way, the plant can have a better chance to grow well and be healthy.

How to propagate Stipa gigantea

Stipa gigantea can be propagated by seed or by division.

Division: Mid-Spring to early summer

  1. Dig up the mother plant clump.
  2. Shake off the excess soil to make it easier to divide.
  3. Divide the clump into good-sized sections. Depending on the size of the clump, use a sharp knife, a spade, or even a saw.
  4. Replant the divisions into the garden 

Seed: Early spring to early summer

  1. Sow the seeds in a well-draining medium. Lightly press the seeds into the soil, just covering them with a thin layer, as the seeds need light to germinate.
  2. Maintain consistent moisture but not soggy (cover with a plastic lid or bag) and provide indirect light. 
  3. For best germination, maintain a temperature around 15 to 18ºC (60 to 65ºF). Germination should take 2 to 4 weeks, but it can also be erratic and take several months.
  4. Water from the base of the container (don´t water overhead)
  5. Once the seedlings have grown a few sets of true leaves, transplant them into individual containers and grow in cold frame during the first winter, or harden them to outdoor conditions and then plant into their permanent positions after the last expected frosts. 

This plant self-seeds easily in stony soil, so you can also wait for it to do this and then transplant the small seedlings.

Sources of information used for this article

Sources

Article from Kew

Article from Jardin-sec

Volume 19 from Flora Iberica

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