Growing Herbs Outdoors: Basil, Parsley, Cilantro, and Mint

I grow basil and flat-leaf parsley every year at the Long Island plot. Basil goes in the ground the last week of May, once nights are consistently above 55°F.

I grow basil and flat-leaf parsley every year at the Long Island plot. Basil goes in the ground the last week of May, once nights are consistently above 55°F. I run three to four plants in a row near the tomatoes — partly for proximity when cooking, partly because basil and tomatoes occupy the same warm-season niche and have compatible soil and water requirements. Parsley goes in earlier, around mid-April, because it germinates in cool soil and tolerates light frost.

Cilantro and mint I also grow, though differently. Cilantro's bolt window in zone 7a is narrow — a spring sowing is done by mid-June, and I restart it in late August. Mint I keep in a container, permanently, because every extension source that covers it mentions containment as the first piece of advice.

This guide covers the four herbs most commonly grown in northeastern gardens. Each has distinct temperature requirements, growth habits, and management strategies.

Basil (Ocimum basilicum)

Basil is native to tropical Asia and is genuinely cold-sensitive. Per NC State Extension Plant Toolbox, basil "requires temperatures above 50°F and does not tolerate frost." Temperatures below 50°F cause chilling injury — leaves develop dark water-soaked spots that turn black and collapse. This is irreversible; a cold-injured basil plant does not recover.

Planting timing (zone 7a): Last frost on Long Island averages April 15-20, but soil and air temperatures do not reach basil's comfort zone until late May. Per NC State, basil should not be transplanted "until soil temperature is at least 60°F." My practice: transplant the last week of May, no earlier.

Starting from seed vs. transplants: Basil is easy to start from seed indoors 4-6 weeks before transplanting. Direct sowing into warm outdoor soil also works. Per Cornell Cooperative Extension, "basil can be started from seed indoors 4 to 6 weeks before the last frost date." Garden center transplants are convenient and less expensive than buying potted grocery-store basil to keep alive (which are grown in very dense plantings and rarely persist).

Spacing: Per Cornell, "space 12 to 18 inches apart in full sun." Crowded basil develops powdery mildew, which is its most common disease.

Pinching for bushiness: Per Penn State Extension, "pinch off flower buds as they form to keep plants leafy and productive." Once basil begins to flower (bolt), leaf quality declines quickly — the leaves become smaller, more bitter, and the plant redirects energy to seed production. Pinch the growing tips weekly once the plant has 6+ nodes, removing the top two sets of leaves with each pinch. I do this every 10 days through July and August.

**Basil downy mildew (Peronospora belbahrii):** Per Cornell Cooperative Extension, "basil downy mildew causes yellowing between the veins on the upper leaf surface, and grayish-purple sporulation on the lower leaf surface." It emerged in the U.S. around 2007 and is now common in humid northeastern summers. Per Cornell, "Genovese types are generally more susceptible than other varieties." The most reliable resistance is in 'Eleonora' and the 'Rutgers Devotion DMR' series developed specifically for mildew resistance. I have grown 'Devotion DMR' for the past two seasons; the resistance holds well through the humid Long Island August.

Soil and water: Per NC State, basil "prefers well-drained soil with a pH of 6.0 to 7.0." Water at the base; overhead watering promotes both downy mildew and Botrytis leaf blight. 1 inch per week is adequate for established plants.