Answer: Lobelia seeds have a pre-germination chill requirement. If your seeds were not pre-chilled prior to sowing, they may still sprout, but it will take them a while to break dormancy on their own before they're able to sprout. You might want to dig one up to check on the status. If the seed hasn't begun to sprout, put the pots or trays into a plastic bag and place in the refrigerator for 10-12 weeks, then put them back into your greenhouse.
Normal seed starting guidelines for lobelia are:
Mix seeds with moistened seed starting mix, place in plastic bag and refrigerate for 10-12 weeks. Remove and sow seeds on the surface of moistened seed starting mix and barely press in with your finger. (Seeds need light to germinate.) Keep at 65F-75F. Seeds will germinate in 15-20 days. The light requirement should be met by regular daylight. After seedlings appear place the trays or pots under a source of artificial light.
Ageratum seeds do not have a pre-germination treatment requirement, but do require light. Sow seeds on the surface of moistened seed starting mix and barely press in with your finger. Keep the soil moist. Seeds will germinate in 10-14 days when kept at 70F-75F. (Regular daylight will meet the light requirement.)
After seedlings appear place trays or pots under a source of artificial light.
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