Cousin It Plant (Casuarina glauca): US Care Guide (2026)
How to grow Cousin It plant (Casuarina glauca 'Cousin It'), the shaggy, weeping groundcover: where it grows in the US, light, soil, watering, containers and the Florida restriction you need to know.
Cousin It is a low, weeping groundcover form of the Australian swamp oak, growing about 6–12 inches tall and 3–4 feet wide. It needs full sun to light shade, very well-drained soil and little water once established. It suits mild-winter areas, roughly USDA zones 9–11, such as coastal California. It is prohibited in Florida, where Casuarina glauca is a state noxious weed.
Casuarina glauca is on Florida's noxious weed list, so it may not be sold or planted there. Related "Australian pines" have invaded Florida beaches and wetlands. In Florida, choose a native groundcover such as sunshine mimosa or beach sunflower instead.
Source: UF/IFAS Assessment of Non-Native Plants, Casuarina glauca.
Cousin It plant at a glance
| Botanical name | Casuarina glauca 'Cousin It' |
| Common names | Cousin It, prostrate swamp oak, dwarf she-oak |
| Family / origin | Casuarinaceae; selected in Australia |
| Plant type | Evergreen groundcover / spiller |
| Size | About 6–12 in tall, 3–4 ft wide |
| Hardiness | Roughly USDA zones 9–11 (hardy to the low 20s °F) |
| Light | Full sun to light shade |
| Soil | Sandy, gravelly or loamy; must drain well |
| Water | Low once established |
| Flowers | Rarely flowers; grown for its foliage |
| Special traits | Fixes its own nitrogen; tolerates wind and coastal conditions |
| Restrictions | Prohibited in Florida |
Where Cousin It grows in the US
| Region | How to grow it |
|---|---|
| Coastal and Southern California, mild Arizona gardens | In the ground year-round, in full sun |
| Gulf Coast and Texas (outside Florida), zone 9 | In the ground; cover during hard freezes |
| Zone 8 and colder | In pots, moved to a bright, cool indoor spot for winter |
| Florida | Do not plant; prohibited by state law |
Hardiness is an estimate based on grower reports. Check with your local Cooperative Extension office or nursery before planting in borderline zones.
How to plant Cousin It
Choose full sun to light shade and soil that never stays soggy. Slopes, rock gardens and wall tops are ideal.
Avoid the hottest summer weeks.
Make the hole twice as wide as the root ball and the same depth.
Keep the top of the root ball level with, or slightly above, the soil to avoid crown rot.
Water deeply, then add a thin layer of gravel or bark mulch kept away from the crown.
Space plants 3–4 feet apart for a continuous groundcover.
Cousin It care: sun, soil, water and feeding
- Sun: full sun gives the densest growth. Light afternoon shade is fine in hot inland areas.
- Soil: any well-drained soil, including sand and gravel. Amend heavy clay with grit, or plant on a mound.
- Water: deeply once or twice a week in the first summer. After that, every 1–3 weeks in dry weather.
- Fertilizer: usually none. Like other casuarinas, it fixes nitrogen through root nodules.
- Salt and wind: tolerates coastal wind and some salt spray.
Cousin It in pots, walls and hanging baskets
Its weeping stems make Cousin It a striking "spiller", especially in cold-winter areas where it can't stay outside.
- Use a tall pot or hanging basket so the stems can cascade.
- Fill with cactus mix or potting mix with one-third grit or perlite.
- Water when the top 2 inches of mix are dry.
- In zones 8 and colder, bring it into a bright, cool room or sunroom before frost.
It is an outdoor plant, so it is not suited to terrariums or low-light rooms.
Pruning Cousin It
- Little pruning is needed.
- In late winter or early spring, cut out any dead or brown stems at the base.
- Trim stems that trail onto paths, cutting back to a branch point.
- Avoid shearing the whole plant, which spoils its shaggy shape.
How to propagate Cousin It
In late spring or summer, cut 4–6 inch pieces of firm stem.
Dip the base and insert it into moist perlite and peat or seed-starting mix.
Cover loosely and keep in bright shade. Rooting is slow and can take 2–3 months.
'Cousin It' is a named cultivar, so seeds (if any form) will not grow true to type. Cuttings are the way to copy it.
Companion plants for Cousin It
| Plant | Why it works |
|---|---|
| Lavender (Lavandula) | Same sun and dry-soil needs; purple flowers contrast with green |
| Rosemary (Salvia rosmarinus) | Upright, aromatic, drought-tolerant |
| Blue fescue (Festuca glauca) | Blue tufts contrast with the weeping texture |
| Sedum and echeveria | Succulent rosettes for rock gardens |
| Agapanthus | Tall flower stems above the low mound |
| Rockrose (Cistus) | Mediterranean shrub with showy flowers |
Common Cousin It problems and fixes
-
Browning or dieback in the center
Usually too much water or poor drainage. Let the soil dry out and improve drainage.
-
Thin, sparse growth
Too much shade. Move it to more sun.
-
Frost-burned tips
Cold below the low 20s °F. Trim damage in spring, and cover the plant during freezes.
-
Pests
Occasional scale or mealybugs. Treat with horticultural oil or insecticidal soap.
Cousin It plant FAQs
What is a Cousin It plant?
Can I grow Cousin It in Florida?
What USDA zones does Cousin It grow in?
Does Cousin It need full sun?
How often should I water Cousin It?
Does Cousin It need fertilizer?
Can Cousin It grow in a pot or hanging basket?
More plant care guides
Turn an interest in the environment into a career skill. The AICPA ESG certificate covers sustainability reporting for finance professionals.
Explore the ESG certificateWritten by the Eduyush team. Florida status checked against the UF/IFAS Assessment of Non-Native Plants in October 2026. Hardiness and size are estimates from grower reports; confirm with a local nursery or your Cooperative Extension office.
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How often should I water my plants?
The watering frequency depends on the type of plant, soil, and climate. Generally, it's best to water when the top inch of soil feels dry. Ensure thorough watering until excess water drains out from the bottom of the pot.
What type of soil is best for my plants?
Most plants thrive in well-draining, nutrient-rich soil. Use a general-purpose potting mix for houseplants, and amend garden soil with compost to improve texture and fertility. Specific plants may have unique soil requirements, so check individual care guides.
How much sunlight do my plants need?
Light requirements vary widely among plants. Most houseplants prefer bright, indirect light, while succulents and cacti need direct sunlight. Shade-loving plants thrive in low light conditions. Always check the specific light needs for your plants.
When should I fertilize my plants?
Fertilize during the growing season (spring and summer) when plants are actively growing. Use a balanced, water-soluble fertilizer every 4-6 weeks. Reduce or stop fertilizing in fall and winter when growth slows down.
How do I prune my plants, and why is it important?
Pruning helps maintain plant health and shape. Remove dead, damaged, or diseased branches and spent flowers. Use clean, sharp tools to make precise cuts. Pruning encourages new growth and flowering.
What are the signs of overwatering and underwatering?
- Overwatering signs include yellowing leaves, root rot, and moldy soil. Underwatering signs include wilted, dry, or brown leaves. Adjust your watering schedule based on these signs and the plant’s needs.
How can I improve humidity for my indoor plants?
Increase humidity by misting plants regularly, placing a tray of water and pebbles near the plants, or using a humidifier. Grouping plants together also helps create a more humid microenvironment.
What should I do if my plant is infested with pests?
Identify the pest type first (e.g., aphids, spider mites, mealybugs). Remove visible pests by hand or with a strong stream of water. Use insecticidal soap or neem oil as treatments. Isolate the infested plant to prevent spread to other plants.
How do I repot my plants, and when should I do it?
Repot when the plant outgrows its current pot or roots start emerging from drainage holes. Choose a pot one size larger, gently remove the plant, loosen the roots, and place it in the new pot with fresh potting mix. Water thoroughly after repotting.
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