October gets dark early and gets darker as it goes. By the back half of the season a significant share of the time anyone sees your porch, they're seeing it at night.
A display that looks composed at noon can disappear entirely at seven.
Start with the light you already have
Before adding anything, find out where your entry light actually reaches. Stand at the sidewalk after dark and look.
Most porch fixtures throw a fairly small pool, usually centered on the door and falling off quickly. If your arrangement sits outside that pool, the cheapest fix is not more lighting — it's moving the display into the light.
Shifting a grouping two feet toward the fixture does more than anything you could buy.
Warm light, always
Cool white and daylight-temperature bulbs make pumpkins look gray and straw look dead. The whole palette is warm — orange, gold, cream, brown — and cool light fights every part of it.
If your entry bulb is a bluish white, swapping it for a warm one changes the display more than any decoration would. It also makes the house look better generally, which is a reasonable thing to get for the price of a bulb.
Light from the side, not straight down
Overhead light flattens everything. It washes out the ribbing on a pumpkin, kills the texture of straw, and removes the shadows that make a grouping read as three-dimensional.
Light coming from the side rakes across those surfaces and brings the texture back. If you're placing anything, place it low and to one side of the arrangement rather than above it.
Less is better
A porch with one warm source and some genuine shadow looks considerably better than a porch lit evenly from four directions.
Shadow is doing work. It creates depth, it separates the grouping from the wall behind it, and it makes the lit portions read as deliberate. Even illumination reads as a parking lot.
Never open flame
Straw and corn stalks are among the most combustible things you can put on a porch, and a fall display puts a lot of dry plant material in one place next to a building.
Anything you add for light should be battery or plug-in. No candles, no flame, no exceptions — and that includes inside a carved pumpkin sitting next to a bale.
What about the pieces themselves
Uncarved pumpkins don't glow, so they're read at night entirely by reflected light. That argues for pale pieces — white and cream pumpkins are far more visible after dark than deep orange or green ones.
If your display is heavy on dark heirlooms and specialty pieces, moving a few white pumpkins to the front is a free improvement to how it reads at night.
Check it at night before you call it done
Arrange the display in daylight, then go back out after dark and look from the sidewalk.
It's a different composition at night — half of what you carefully arranged is invisible and the parts still showing may not be the parts you'd have chosen. Adjusting for that takes ten minutes and it's the step almost nobody does.