Degroot's Spire Arborvitae (Degroot's Spire) care

Light

Degroot's Spire Arborvitae needs sun on the leaves, not just bright ambient room light. Full sun for the densest, tightest spire and best colour; tolerates light shade but becomes looser and slower with under 6 hours of direct sun. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Water degroot's spire arborvitae two to three times weekly while young; weekly once established. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Maintain even soil moisture, especially the first two seasons and in drought. Mulch the root zone; avoid both drought and waterlogged conditions.

Soil and pot

Degroot's Spire Arborvitae grows best in moist, fertile, well-drained loam. Adaptable to most soils but prefers neutral to slightly alkaline, evenly moist ground with good drainage. Improve poor soils with organic matter. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Degroot's Spire Arborvitae sits happiest at around Ambient outdoor humidity humidity and -37 to 30°C (-35 to 86°F). An outdoor columnar conifer indifferent to humidity; good airflow between plants reduces fungal needle blight in humid regions. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed degroot's spire arborvitae sparingly. Feed once in early spring with a balanced slow-release or evergreen fertiliser. A light second feed in early summer aids young plants; avoid late-season nitrogen that pushes frost-tender growth. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on degroot's spire arborvitae in the Growli community. Each is annotated with the most common cause so you know where to start.

• Snow/ice splaying — The slim column is prone to splaying under snow load; tie loosely with twine and clear heavy snow to keep the spire intact.
• Winter browning — Drying winter winds can bleach foliage; water well before freeze-up and shelter exposed plantings.
• Bagworms — Silk bags defoliate branches; hand-pick in winter or treat early-summer larvae.
• Drought-induced interior browning — Dry soil browns inner foliage; consistent watering and mulch keep the spire dense.

Propagation

Propagated from semi-hardwood cuttings taken in late summer to autumn, treated with rooting hormone under mist or in a humid frame. Cuttings root reliably and stay true to the cultivar; seed does not reproduce the form. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Degroot's Spire Arborvitae is mildly toxic to pets. Thuja occidentalis is not individually listed on the ASPCA toxic or non-toxic plant lists; treat with caution and verify with a vet. The foliage and essential oil contain thujone, which in sufficient quantity can cause drooling, vomiting, diarrhoea, and potentially neurological signs in dogs and cats. Prevent ingestion and monitor pets that chew it. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Degroot's Spire Arborvitae deep-dive guides

Every aspect of degroot's spire arborvitae care, each with its own calibrated guide:

• Degroot's Spire Arborvitae watering schedule
• Degroot's Spire Arborvitae light requirements
• Best soil mix for degroot's spire arborvitae
• Degroot's Spire Arborvitae fertilizing guide
• When to repot degroot's spire arborvitae
• How to propagate degroot's spire arborvitae
• Degroot's Spire Arborvitae growth rate & size
• Degroot's Spire Arborvitae cold hardiness
• Degroot's Spire Arborvitae temperature & humidity
• Is degroot's spire arborvitae toxic to cats & dogs?
• Is degroot's spire arborvitae toxic to cats?
• Is degroot's spire arborvitae toxic to dogs?
• Getting degroot's spire arborvitae to bloom

Featured in these plant shortlists

Degroot's Spire Arborvitae qualifies for 4 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best drought-tolerant houseplants — Houseplants that prefer to dry out — forgiving of forgotten watering and ideal for travel or busy weeks.
• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
• Best houseplants for a cool room — Houseplants that tolerate cool conditions down to about 10°C — for an unheated spare room, hallway, porch or a home kept cool.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Degroot's Spire Arborvitae is also commonly called Degroot's Spire or Columnar Arborvitae.

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