Choosing a Humidity Dome and Kit Configuration
The right
AC Infinity humidity dome depends on how many seedlings or clones go into the tray and whether you already own propagation lighting and heat. For 6-8 seedlings, the 5x8 dome is the right size. For a full 12-18 cell 1020 half-tray, the 6x12 is the standard. Kit choice comes down to whether you want a self-contained propagation station out of the box or you're adding the dome to existing gear.
Dome Size and Kit Options
Propagation Environment Targets
Seedlings and clones want 75-80F substrate temperature and 80-90 percent humidity for the first 7-10 days. The Suncore heat mat included in the germination kits holds the substrate at the right temperature without baking it. Once roots establish (day 7-10 for seedlings, 10-14 for clones), step humidity down to 60-70 percent by opening the dome vents progressively. Skipping the heat mat is the most common reason for slow germination; substrate that's 10F cooler than ambient air slows or stalls the seed completely.
For full setup details, see
how to set up an indoor grow tent.
Related Guides
Pair the dome kit with
AC Infinity grow lights for the veg transition. Cross-brand options live in the broader
propagation lineup.
Frequently Asked Questions
What humidity do seeds need to germinate?
Seeds germinate fastest at 80-90 percent humidity and 75-80F substrate temp. The dome holds RH high without misting; the heat mat warms the substrate to the target band. Once the cotyledons open and true leaves appear (day 7-10), step humidity down progressively to 60-70 percent.
Do I need a heat mat under the dome?
Yes if your room runs cooler than 75F. Substrate temp drives germination speed more than ambient air temp. The Suncore mat in the germination kit holds substrate at the target without overheating. Skipping the mat in a cool room is the most common reason for slow or failed germination.
5x8 vs 6x12, which one?
The 6x12 is the standard size; it fits a 1020 half-tray with 12-18 cell inserts. The 5x8 is for very small propagation runs (single clone, 6-8 seedlings) or where shelf space is tight. For most home grows starting 4-8 plants, the 6x12 gives more flexibility for staggered germination.
When do I open the vents?
Start fully closed for days 1-5 (germination + initial root growth). Crack the vents 25 percent open from day 5-10 as cotyledons open. Open fully from day 10 onward to harden seedlings for transplant. Leaving the dome sealed past day 10 promotes damping-off fungal issues.
How long does the dome stay on?
10-14 days for seedlings, until first true leaves are fully developed. For clones, leave the dome on 7-10 days until roots have established through the rockwool or rooting plug. Remove the dome gradually (vents open, then dome propped, then dome off) over 2-3 days to avoid shocking the plants.
Does the dome work for clones?
Yes, the same dome works for clones with a slight adjustment: keep humidity at 90-95 percent for the first 5 days (vents fully closed), then ease down as roots form. Use rockwool cubes or rapid rooters in the tray. The heat mat is even more important for clones since rooting hormone activity drops sharply below 72F substrate temp.
