Do you have Hot Date and Explode O'Nut ?
The Hot Date and Explode O'Nut combination can be very effective with the nut placed to the right of Hot Date.
Gives more time for SUN production and to add offensive plants to the far left of Hot Date.
I am using this combo with level 1 plants and so far doing very well.
If you have the necessary 250 seeds to unlock a plant purchased with seeds (seedium) then it may be possible to upgrade it to level 5 without buying more seeds.
Buy it, unlock it then leave the game without doing anything else then go straight back to it.
If you're lucky the plant is unlocked and the 250 seeds are still available to level it up to level 5.
This seems to work on all "seedium" plants, from my own experience it works half the time (i have 3 profiles) but you only get one attempt.
This is a longstanding glitch and EA may have fixed it so it no longer does it.
Plant Food damage ?
Not plant food damage but boosted damage.
Don't upgrade a plant off the plant selection screen in battlez as there is a possibility of a crash leading to streak loss. 👍