Narrowleaf Four O'clock

Year-round

Narrowleaf Four O'clock is native to the Great Plains and dry western states, not to Ohio or the Columbus area. It is a low, sprawling perennial that grows from a deep taproot and opens white to pink flowers in late afternoon and evening. In a Columbus garden it is grown as an ornamental xeric novelty, and the main care challenge is that it comes from a much drier climate than central Ohio's humid, clay-heavy soil, so drainage matters more here than it would in its native range.

• Give it full sun and the best-draining spot you have, it comes from dry western prairies, not humid Ohio clay
• It grows from a deep taproot and does not transplant well once established, choose its permanent spot the first year
• Water only when the top few inches of soil are dry, overwatering in Columbus's regular rainfall is the main way this plant fails here
• Keep pets from chewing the roots and foliage, a close relative in the same four o'clock genus, Mirabilis jalapa, is documented as toxic to dogs and cats

Fall

As nights cool and Columbus gets its first fall frost, the top growth will blacken and die back to the ground. The taproot itself survives underground through central Ohio winters, so leave it in place rather than digging it up. Do not move or divide it in fall, the root is deep and brittle and disturbing it now can kill the plant before winter.

• After a hard frost blackens the foliage, cut the dead top growth back to a few inches instead of pulling the whole plant
• Do not dig up or move the taproot in fall, it is deep and brittle and disturbing it now risks killing the plant before winter
• Skip fall fertilizer, it pushes tender new growth right before frost that just dies back anyway
• A light layer of mulch over the root crown after cutback helps buffer Columbus's freeze-thaw cycles, which are harsher than this plant's native western winters

Cutting the blackened stems back to a tidy stub after frost keeps the front bed looking intentional through fall cleanup season, which is HOA-friendly.

Winter

This plant is dormant in winter and needs nothing above ground. The bigger risk in Columbus is wet, slow-draining soil freezing and thawing around the taproot, a condition its native dry western range rarely puts it through.

• Do not water in winter, the dormant root wants the soil on the dry side, not wet from sitting snowmelt
• If a bed drains slowly you will see it in winter, standing water or ice over the root zone is the main way this plant is lost in Ohio
• Leave the cut-back stems and mulch in place, there is nothing to prune or feed until new growth appears in late spring
• If winter dieback looks worse than expected, wait until late spring before assuming it is dead, this plant can be slow to resprout even in its native range

Spring

Wait until after Columbus's last spring frost and until the soil has dried out from spring rain before planting or moving divisions. Central Ohio's clay holds water and stays cold longer than the dry, rocky, or sandy ground this plant grows in naturally, so spring is the time to fix drainage before growth takes off. New shoots from the taproot can be slow to emerge here compared to its native western range.

• Wait to plant until after the last spring frost and until spring rain has drained through the bed
• Work coarse sand or fine gravel into heavy clay before planting so water moves away from the taproot
• New growth from the taproot can emerge later here than in its native western range, do not assume it died over winter
• Skip fertilizer at planting, rich wet spring soil encourages soft growth that struggles once Columbus's humid summer arrives

Summer

Summer heat is when this plant is happiest, since it comes from hot dry prairies, but Columbus's humid summer rain is the main risk here. Flowers typically open in late afternoon and stay open into the evening, closing again by the next morning, which is where the common name comes from.

• Let the soil dry between waterings, in a normal Columbus summer this plant usually needs no supplemental water at all
• Flowers open in late afternoon and evening and close by the next morning, plant it somewhere you use the yard in the evening
• Good air movement around the base helps foliage dry out fast after summer thunderstorms and lowers the chance of rot
• Deadheading is optional, it does not change bloom timing much for this species