Ah, the fragrance of basil is just so summery, and it is not uncommon for gardeners to want to keep this vibe alive by bringing basil indoors for winter. However, more often than not, the love affair comes to an abrupt end once basil sets its mind to flowering and drying up in the diminishing daylight hours of fall. So what can be done to succeed with basil indoors?
1) The first tip is to keep basil peaking now, outdoors, even as fall is getting close. Don't stop watering and fertilizing (basil loves nitrogen, so Sea Soil, fish fertilizer, and Evolve All Purpose Organic are recommended options for feeding). Also, don't be shy to cut flowering basil back by 1/3. This encourages leafy regrowth as opposed to the setting of new flowers.
2) Variety selection makes all the difference! Pesto Perpetuo and Aussie Sweetie basils are the two non-flowering selections, and these can last all year round (provided enough light) since they do not try to flower in fall. And the flavour is amazing on these two!
3) Try taking stem cuttings to start new basil for indoors - this works particularly well for the non-flowering types, but you can also cajole more life out of traditional basils as well. Simply cut healthy stem pieces (4 - 6") and root in water; pot into rich container mix using any type of pot with drainage holes. The smaller cuttings are easier to manage indoors vs. a full summer-grown plant.
4) Start fresh basil seeds, using the "dense planting"method that applies to baby greens production (50+ seeds in a 6" pot). Grows lights will help a lot, especially from November - early March.