I don’t think it would be a bad idea per say, but is it needed?
Those plants are not showing any deficiencies that I can see. If you want maybe give a half or quarter strength dose just as a preventative measure.
I might be more inclined to give a watering with something like Recharge or another microbe product. Worm tea maybe. That would naturally unlock whats already in the dirt. In the ground they will root far and deep so getting food to the roots will take time. Watch for yellowing leaves starting from the bottom up as a sign of being hungry. A few random yellow leaves are normal even for a healthy well fed plant, but if its widespread then you will need to start feeding.
The FF Trio is very salty and the mineral salts will build up over time and submarine your root zone pH. There’s no way to manage this in the ground. Indoor growers will do a flush to get rid of the salts. It’s not possible to flush out the salts if you have plants in the ground.
I would use a less salty product like Jacks 321.
I really wish I knew more about in ground gardening so I could give you more solid advice on what you should use, but I’d definitely encourage you to choose something other than FF trio.
I’ve grown several hundred autos indoors over the years, and I have a very good eye for their potential. You have 2 really great looking little autoflowers right there that have potential to be true monsters. The care they get over the next couple of weeks will mean an awful lot.
Indoors, or outdoors in pots I’d recommend Advanced Nutrients. That’s what I’ve been using for many years now and I’m really happy with it. I’d assume it’s fine for in ground gardening as well, but you can always contact them by phone or email and get their advice. I’m sure the amounts you feed in ground will be different, because I’m using runoff to rinse out some of the previous feeding each time I water/feed them. That won’t be the case in the ground.
I’ve never used Jack’s, but tons of people here use it and swear by it. Hopefully someone who uses it outdoors will chime in for you.
In the meantime, you can give them some Big Bloom. It definitely won’t harm them and it’s better than nothing while you figure out how you want to proceed.
Ff trio is def more salty then most but if you ph properly, it should be ok. Soil in ground plants has the earth itself to help buffer the soil. Outdoors your better suited for a more organic style grow by either making your own soil with all the goodies, or just the simple dry amendment type nutes. Fox farms does have a dry nutrient amendment that would work great for what your doing. Look into thar maybe instead of liquid nutes.
Any dry amedment nutes you would suggest. I believe ive used nitro bat before
Fox farms has whats called happy frog fruit and flower, happy frog all purpose. Basically scratch in x amount every 3 to 4 weeks and water only from there. Give that a read, might be something more suited for you
Awesome thank you 
Either that or you could get some buds n bloom dry amendments for flowering from Coast of Maine. They also have Organic plant food for veg and worm castings as a special treat!
We switched to Jacks 321. Had a decent stash of these. We feed at 50% Maybe every 3 watering. Still using the three of these due to amount on hand.
I used FF liquid trio and PK booster trio for like 2 years. Works great just remember, water in between feeds, (feed, water, feed, water) if using RO water add calmag, and always flush the soil when the schedule calls for it between weeks 4 and 5, 7 and 8, 10 and 11. Either with water or sledghammer. These things will keep your soil ph in check and insure your plant is well fed. Another good tip is to always water to at least 15% runoff, even in feed days. This helps keep the salt levels low and help avoid soil ph dives.
I was reading about coast of main buds n bloom. Ordered a bag