Hilchos Shemittah v’Yoveil 4:13

The preceding case is similar to harvesting shemittah produce in the eighth year, i.e., the status of grain, legumes and tree fruit depends on when they reached the stage of tithing; the status of rice, millet, poppy, sesame and Egyptian beans that were planted to produce seed depends on when they complete their growth, and the status of vegetables depends on when they’re harvested.

Hilchos Shemittah v’Yoveil 4:14

If someone plants Egyptian beans for seed in the sixth year and the produce is complete before the Rosh Hashana of shemittah, both the vegetable and the seeds are permitted during shemittah. If it was planted for the vegetable and it entered shemittah, both the vegetable and the seeds are prohibited like the aftergrowth of shemittah. Similarly, if one planted it for both the seed and the vegetable, it is prohibited.