Giant Day Gecko among rainforest foliage

Geckos · Care guide

Giant Day Gecko Care Guide

Phelsuma grandis

Beautiful arboreal day geckos from coastal northwest Madagascar — males can reach about 12″. Glass terrarium with mesh-lid heat and T5 12% UV, humidity 60–80%, cork and multi-height branches, and a diet of insects plus jelly pots, fruit purees, and dried formulas.

At a glance

Quick facts

Key parameters for day-to-day husbandry. Full detail is in the sections below.

  • Cool-end set

    76–78 °F

    24–26 °C · ~6″ off substrate

  • Night target

    ~70 °F

    ~21 °C · ~10 °F drop

  • Humidity

    60–80%

    Spray 2×/day

  • UVB

    T5 12%

    On top of mesh lid · replace yearly

01 · Housing

Enclosure & housing

Arboreal diurnal day geckos from Madagascar. Humidity 60–80% suits a glass terrarium with mesh-lid heat and T5 12% UV, cork bark, multi-height branches, foliage for cover, and a cool-end water bowl.

Adult minimum size

18″ W × 18″ D × 24″ H

Glass terrarium for an arboreal day gecko. Heat dome and T5 12% UV sit on the mesh lid.

Decor

  • Cork bark and stable climbing branches at different heights
  • Foliage for cover and additional hiding places
  • Heat dome on the mesh lid (warm back corner) + cool-end probe ~6″ off substrate
  • Cool-end water bowl (de-chlorinated water); moisture also from live foods

Substrate

  • Humidity-retentive mix of coir and coarse orchid bark — bio substrates work well
  • Complete bio setups with live planting and cleanup crew work extremely well; do not waterlog the substrate
  • Full clean about every six weeks if kept relatively clean — replace substrate and disinfect decor

Cleaning

  • Daily: spot clean to keep the environment fresh and limit bacteria
  • About every six weeks: full clean if kept relatively clean — replace substrate, disinfect decor and terrarium

Housing diagram

Enclosure example

Front view 18″ wide × 24″ tall (depth 18″) · mesh lid · branches · foliage · cool water bowl · coir + orchid bark

Example Giant Day Gecko glass terrarium front view at 18 inches wide by 24 inches tall Front elevation of an adult Giant Day Gecko glass terrarium at 18 by 24 inch proportions with 18 inch depth. Heat dome sits on the mesh lid in the warm left-back corner. A T5 12% UV tube sits on top of the mesh lid. Climbing branches fill multiple heights, with a vertical branch under the heat leaning about 25 degrees toward the cool side. Foliage provides cover. A water bowl sits on the cool-end floor. Substrate is humidity-retentive coir mixed with coarse orchid bark. ADULT MINIMUM · FRONT 3:4 18″ W × 18″ D × 24″ H MESH LID 24″ tall 18″ wide · depth 18″ · height 24″ Branches Foliage Water bowl Coir + orchid bark WARM COOL
  • Front proportions — 18″ wide × 24″ tall (3:4); depth 18″ — adult minimum
  • Mesh lid — heat dome and T5 12% UV tube sit on top of the mesh
  • Branches — cork bark and multi-height branches for an arboreal lifestyle
  • Foliage — cover and naturalistic décor
  • Water bowl — cool end for drinking (treated water)
  • Substrate — coir + coarse orchid bark; mist without waterlogging

Setup diagram · 1 of 2

Top-down view

Heat dome in a back corner · probe on the opposite cool end · recommended temps need this layout

Terrarium top-down: heat dome in back corner and cool-end thermostat probe Rectangular glass terrarium viewed from above. Heat dome sits on the mesh lid in the left back corner. Thermostat sensor enters on the opposite side and rests at the back cool corner so the cool-end temperature can be monitored. BACK FRONT Heat dome Back corner · mesh lid Thermostat probe Opposite cool corner via lid nodule WARM COOL

Setup diagram · 2 of 2

Front view

Looking into the terrarium · dome on the mesh lid · probe about 6″ off the substrate

Terrarium front view: heat dome on mesh lid and probe six inches off substrate Front elevation of the glass terrarium. Heat dome sits on the mesh lid toward the warm left back corner. Thermostat probe enters on the cool right side and rests about six inches above the substrate so cool-end temperature can be set to 76 to 78 degrees Fahrenheit by day. MESH LID FLOOR / SUBSTRATE back wall (behind) Heat dome Back corner on mesh ≈ 6″ Thermostat probe Cool end · opposite dome ≈ 6″ off substrate WARM COOL Cool-end probe target: 76–78 °F (24–26 °C) day · ~70 °F (20 °C) night
  • Heat dome — on the mesh lid in a back corner (this guide uses the left-back warm end)
  • Probe — opposite cool end via lid nodule; tip about 6″ off the substrate to monitor cool-end temperature

02 · Climate

Temperature, UVB & humidity

Cool-end set 76–78 °F with ideal probe 80 °F, T5 12% UVB on the mesh lid, and humidity around 60–80% with twice-daily misting.

Daytime temperature gradient

When the heat bulb and thermostat sensor are placed as instructed, a probe target of 80 °F (27 °C) ideal · cool set 76–78 °F · ~6″ off substrate creates this spread. The probe point is not the basking spot.

Daytime temperature gradient by zone, plus night drop
Zone Temperature
Cool end (set) 76–78 °F (24–26 °C)
Probe target (thermostat probe target) 80 °F (27 °C)
Basking spot (hottest point under bulb) ~90–95 °F (~32–35 °C)
Night drop Reduce thermostat by ~70 °F (~21 °C) · ~10 °F drop (cool set ~68 °F)

Photoperiod & night

  • Winter: about 12 hours light/heat
  • Summer: up to 16 hours when days are longer
  • Night: about 10 °F drop · thermostat ~70 °F (21 °C) / cool set ~68 °F
  • Night drop lets metabolism slow — essential for the gecko

UVB lighting

  • T5 12% UV tube on the mesh lid
  • Sits on top of the mesh lid — never under (straight across or as preferred)
  • Replace every 12 months — UV output degrades over time
  • Match UV on/off to the heat schedule

Climate diagram

Lighting setup

Glass terrarium mesh lid — T5 12% UVB sits on top of the lid · heat dome on the warm end · match UV to heat

Glass terrarium: T5 12% UV tube sits on top of the mesh lid with heat dome on the warm end Front view of a Giant Day Gecko glass terrarium with a mesh lid. The T5 tube with 12 percent UV output sits on top of the mesh lid — never under it. A heat dome also sits on top of the mesh at the warm end. Photoperiod is 12 hours in winter and up to 16 hours in summer when days are longer. FLOOR MESH LID T5 12% UV tube Sits on top of mesh lid Heat bulb / dome On mesh lid · warm corner WARM COOL PHOTOPERIOD (HEAT + UV TOGETHER) Winter 12 h Summer up to 16 h
  • T5 12% UV tube — sits on top of the mesh lid of a glass terrarium (never under the lid)
  • Heat dome — also on top of the mesh lid at the warm back corner; same day/night schedule as UV
  • Photoperiod — 12 hours in winter, up to 16 hours in summer
  • Humidity — about 60–80% RH; spray twice daily (fogger or misting OK); allow drier periods

Humidity around 60–80%

  • Spray manually twice daily — foggers or misting devices can help
  • Slightly drier periods during the day are perfectly safe and normal
  • Do not obsess over holding one RH figure every minute of the day
  • Constant wetness significantly increases bacteria buildup — allow ventilation and drier periods

Daily humidity cycle

Target about 60–80% RH with twice-daily misting; slightly drier periods are normal.

  1. 1 · Day

    60–80% RH · spray 2×

    Manual spray twice daily; fogger or misting device optional

  2. 2 · Daytime

    Slightly drier OK

    Do not obsess over a fixed RH every minute — drier periods are normal

  3. 3 · Ventilate

    Not always wet

    Constant wet conditions raise bacteria risk — allow drier periods and airflow

First power-up tip

Always have the dimming thermostat dial turned down before you plug it into the mains for the first time. Set the cool side to 76–78 °F (24–26 °C); ideal daytime probe point is 80 °F (27 °C) once dome and sensor are in place.

03 · Nutrition

Diet & feeding

Insects plus jelly pots, fruit purees, and dried formulas — method of 5, dust every feed, gut-load insects. Food size no larger than the distance between the eyes.

At a glance

Feeding cheat sheet

Method
Offer 5 insects at a time and wait until eaten before adding more · also jelly pots, fruit purees, dried formulas
Adults
About 5–10 crickets often consumed daily once settled
Dust
Every feeding · 4:1 calcium : Nutrobal
Food size
No larger than the distance between the eyes

Staple insects

Fed regularly

  • Crickets
  • Locusts
  • Calci Worms
  • Jelly pots, fruit purees & dried formulas

Occasional treats

In moderation only

  • Waxworms
  • Morios

Supplements — every feeding

Dust every feeding with a 4:1 mix of calcium : Nutrobal (4 parts calcium to 1 part Nutrobal). Mix before dusting, then coat the food on every feed.

Feeding new geckos — “method of 5”

New arrivals often will not eat well for the first few days. This is normal. Once settled, appetite usually increases — exact cricket/locust counts vary.

  1. Offer 5 insects at a time

  2. Wait until you see them consumed before adding more

  3. Reduces uneaten insects, stress, and possible insect-related injuries

Adult intake

  • About 5–10 crickets commonly consumed daily once settled
  • Insect staples plus jelly pots, fruit purees, dried formulas, and occasional treats
  • Hand feeding can help bonding — excessive hand feeding can lead to obesity
  • Hunting and chasing food provide exercise and enrichment

Water

  • They drink from a cool-side water bowl
  • Moisture also comes from live foods — do not worry if you rarely see them drinking
  • Treat all water with a de-chlorinator

Gut-load insects before offering — variety matters for calcium-to-phosphorus (Ca:P) and vitamins.

Why gut loading matters

Feeder insects must be well fed before offering. In the wild, lizards and amphibians scavenge a wide variety of prey that themselves ate varied foods — supplying complete nutrition and a better calcium-to-phosphorus (Ca:P) ratio.

  • Use commercial gut-load foods with quality ingredients
  • Add fresh reptile-safe vegetables for variety
  • A single piece of carrot or potato is not enough — poor Ca:P and limited vitamins/minerals

Speak to a member of staff for more feeding advice.

04 · Behaviour

Handling & behaviour

Patience first. Settling and regular feeding come before handling.

  1. Step 1

    Settle first

    Allow the gecko to settle in the new enclosure and begin eating regularly before handling. Adapting is stressful; early handling can make it worse.

  2. Step 2

    Short sessions

    Initial sessions: 5–10 minutes only. Lengthen as the gecko becomes more comfortable.

  3. Hygiene

    Wash hands

    Always wash or disinfect hands before and after handling to prevent bacteria transfer both ways.

  4. Warning

    No aerosols

    Do not use aerosols or plug-in air fresheners near the enclosure — the chemicals can harm your gecko.

05 · Welfare

Health & welfare

Prevention starts with correct husbandry — heat, UVB, hydration, and supplementation working together.

Best prevention: good husbandry

Correct temperatures, supplementation, hydration, and UVB keep the immune system and gut working well — supporting essential physiological processes.

Inert substrates Paper, lino, carpet — pros & cons

Pros

  • Lower impaction risk

Cons

  • Limit natural behaviours such as digging
  • Can increase faecal contamination (waste less absorbed)

Questions

FAQ

What size tank does a Giant Day Gecko need?

Adult minimum is 18″ wide × 24″ high × 18″ deep glass terrarium. Provide cork bark, stable multi-height branches, and foliage for cover and hiding places. Use humidity-retentive coir mixed with coarse orchid bark (bio setups with live plants and cleanup crew work extremely well). Heat dome and T5 12% UV sit on top of the mesh lid. Cool-end probe about 6″ off the substrate opposite the heat. Place a water bowl on the cool side.

How do I set heat and probe for a Giant Day Gecko?

Place the heat dome on the mesh lid in a back corner (this guide uses left-back). Feed the dimming thermostat sensor through the opposite lid nodule so it rests about 6″ off the substrate on the cool end. Set the cool side to 76–78 °F (24–26 °C) by day; ideal daytime temperature at the probe point is 80 °F (27 °C). That creates a gradient from about 76 °F up to roughly 90–95 °F under the basking spot. At night, reduce about 10 °F — cool set around 68 °F or thermostat about 70 °F (21 °C). Recommended temps only apply with this placement.

What humidity and UV do Giant Day Geckos need?

Aim for about 60–80% relative humidity. Spray the enclosure manually twice daily; foggers or misting devices can help. Slightly drier periods during the day are safe and normal — do not keep the enclosure constantly wet (bacteria risk). Use a T5 12% UV tube sitting on top of the mesh lid (never under). Replace UV tubes every 12 months. Photoperiod about 12 hours in winter and up to 16 hours in summer.

When can I start handling my Giant Day Gecko?

Allow the gecko to settle and begin eating regularly before handling — at least two successful feeds first. Early sessions 5–10 minutes only; lengthen as they become more comfortable. Always wash or disinfect hands before and after. No aerosols or plug-in air fresheners near the enclosure.

What and how often do Giant Day Geckos eat?

Live insects, jelly pots, fruit purees, and dried formulas. Use the method of 5 (five insects at a time until eaten). Once settled, 5–10 crickets daily is common. Staples: crickets, locusts, and calci worms; waxworms and morios in moderation. Dust every feed with a 4:1 calcium : Nutrobal mix. Food size no larger than the distance between the eyes.

Next steps

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