The same reason you wouldn’t plant seed for say a peach, apple, or other fruit you got from a farm stand - lack of providence. It’s the same reason people would put the time or effort into buying specific fruit tree cultivars as opposed to growing it from grocery or farm bought seed.
The world of garlic is more complicated than most people think. It’s not just hardneck vs softneck. There are 10 different garlic families, 8 hardneck, 2 softneck. Of those 8 hardneck, there are substantial differences in strength of flavor, climate suitability, harvest time, clove wrapping tightness (which affects storage), clove size and number, scape production etc…
Organic Garlic Seed Variety Comparison Chart | Filaree Farm - I don’t find this chart hard and true for every detail, but it’s still a very good guide.
“Creole” garlic for example has hotter growing requirements, but grows nice size bulbs, many describe as sweeter garlic with almost a year of storage similar to softnecks. Meanwhile “Asiatic” garlic cultivars harvest much earlier in the season (June for me), but are more sulfurous, looser wrapped, poor storing (maybe 4 months), with very large cloves.
If none of that matters and you just want garlic, then it’s perfectly fine to go ahead and plant from grocery bought or fruit stand bought. Though, I’d imagine the fruit stand or garlic stand should be able to tell you cultivar.
If you have clear objectives concerning flavor, storage, scape production, bulb size, onion maggot resistance, then the $25 or whatever per pound may be worth it.
Here’s my example of some of the differences between garlic families. These are some of the larger though not largest bulbs from each cultivar planted.
Left to right:
- Uzbek - Turban garlic
- Spanish Roja - Rocambole - This family produced a lot of whooper sized bulbs. Like Elephant garlic sized in some cases. There are larger bulbs but we have eaten many of them already.
- California White - we think this is Cal White, it’s from replanted grocery store bought softneck garlic
- Nooka Rose - Silverskin
We trialed like 30-40 something cultivars this year. There are substantial growth differences in most of them, mainly between families. You won’t know until you try for your location. Asiatics should produce scapes, but for our location, they are stingy. Turbans which should struggle meanwhile, produce nice scapes here. (This should be the reverse according to the chart and conventional knowledge.)
Garlic can exhibit epigenic differences so localized strains can quickly arise. The downside is that the world of garlic can be quite costly if you like sampling different cultivars. The cost can add up like it does in the world of figs.