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.

—- title: "Growing Herbs Outdoors: Basil, Parsley, Cilantro, and Mint" slug: growing-herbs-outdoors hub: vegetables category: Vegetable guide description: "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." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 10 —-

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.

Parsley (Petroselinum crispum)

Parsley is a biennial — in its first year it produces leaves; in its second year it flowers, sets seed, and dies. Most gardeners treat it as an annual, replanting each spring. The two main types: flat-leaf (Italian) parsley, which has better flavor for cooking, and curly parsley, which is hardier and more ornamental.

Per Penn State Extension, parsley "tolerates light frosts and can be planted 3 to 4 weeks before the last frost date." In zone 7a, this means mid-to-late April transplanting or direct sowing.

Germination is slow. Per Cornell Cooperative Extension, parsley seeds "may take 2 to 4 weeks to germinate because of germination inhibitors in the seed coat." Soaking seeds in warm water for 12-24 hours before sowing speeds germination. Seed viability also declines with age — use fresh seed each season.

Spacing and growth: Per Penn State, space parsley "8 to 10 inches apart." It grows 12-18 inches tall and forms a rosette of stems from a central crown. Harvest outer stems first, leaving the crown intact to continue producing.

Overwintering: In zone 7a, flat-leaf parsley frequently overwinters with light protection. Per Cornell, "parsley is hardy to zone 5" and may overwinter in zone 7 without any protection. In my experience, flat-leaf parsley planted in May overwinters through the Long Island winter and resumes growth in March of the following year — though it will bolt and flower by May of year two. This provides a two-season harvest from a single planting.

Swallowtail butterfly host: Black swallowtail butterfly (Papilio polyxenes) larvae feed on parsley, dill, and other Apiaceae. Per Xerces Society, parsley is a "host plant for black swallowtail caterpillars." I plant extra parsley specifically to support the larvae. The caterpillars are striped in green, white, and black and are not harmful to the garden.

Cilantro (Coriandrum sativum)

I don't grow cilantro as consistently as basil and parsley — the bolt window in zone 7a is narrow enough that it requires more careful scheduling than most gardeners want to manage. The information here is sourced from extension research; I grow it in short successions rather than as a permanent feature.

Cilantro is a cool-season herb that bolts rapidly in heat and long days. Per NC State Extension Plant Toolbox, cilantro "bolts and goes to seed quickly in warm weather." In zone 7a, the spring window for leaf harvest runs from approximately April 1 through late May; after that, bolting makes leaf harvest unproductive.

Planting timing: Per Oregon State University Extension, "sow cilantro directly in the garden in early spring as soon as the soil can be worked." Direct sowing is preferred over transplanting because cilantro forms a taproot and resents root disturbance.

Succession planting: Per Penn State Extension, "successive plantings every 2 to 3 weeks" extend the harvest window. In zone 7a:

• Spring successions: April 1, April 15, May 1 (expect bolting to end leaf harvest by early to mid-June)
• Fall successions: August 20, September 5 (harvest through October)

There is no cilantro succession schedule that produces quality leaves through a zone 7a July or August. The gap is unavoidable.

Slow-bolting varieties: Per Johnny's Selected Seeds, varieties such as 'Slow Bolt' and 'Calypso' extend the leaf harvest by "up to 3 weeks longer" than standard types before bolting in warm conditions. This does not eliminate the summer gap but extends the spring season slightly.

Coriander seed harvest: When cilantro bolts and flowers, the resulting seeds are coriander. Per NC State, "allow seeds to dry on the plant, then harvest before they shatter." Coriander seed is useful in cooking and can be saved for the next year's planting.

Mint (Mentha spp.)

I grow mint in a container, as do most experienced gardeners who have tried growing it in-ground once. The warning is universal and well-founded.

Per Penn State Extension, "mint spreads by underground rhizomes and can quickly take over a garden bed." Per Clemson HGIC, "containment is strongly recommended" for all Mentha species. A single plant left uncontained can spread 8-12 feet in a single season in ideal conditions.

Container culture: A 5-gallon container controls spread effectively. Mint is not particular about soil — it grows in almost any well-drained medium. Per Clemson HGIC, mint "prefers partial shade to full sun and moist soil." In zone 7a, a container in morning sun with afternoon shade produces better leaf quality than full afternoon sun, which can cause wilting and stress.

Species differences: Several species are commonly grown:

• Mentha spicata (spearmint): mild, classic mint flavor; most common
• Mentha x piperita (peppermint): stronger, menthol-forward; a hybrid of spearmint and watermint
• Mentha suaveolens (apple mint): fuzzy leaves, mild fruity flavor

Per Clemson HGIC, all are managed the same way — containers or root barriers.

Harvest technique: Harvest mint by cutting stems to just above a leaf node. Per Penn State Extension, "regular harvesting prevents woodiness and keeps plants producing new, tender growth." Cut back by one-third in midsummer if the plant becomes leggy.

Overwintering: Per Clemson HGIC, mint is hardy to zone 5 and will overwinter in-ground or in an unheated garage if the container doesn't freeze solid. In zone 7a, containers outdoors overwinter reliably with minimal protection.

Herb Comparison

Common Problems

Frequently Asked

When should I plant basil outdoors?

Per NC State Extension, basil should not go outdoors until soil temperature is at least 60°F and nighttime temperatures are consistently above 50°F. In zone 7a Long Island, this means the last week of May. Planting earlier risks chilling injury — even a single night below 50°F can permanently damage basil leaves.

Why does my cilantro always bolt?

Because cilantro is a cool-season herb and temperatures above 75°F trigger bolting. Per NC State Extension Plant Toolbox, "bolting is inevitable in warm weather." No amount of watering or shading reliably prevents bolt in a zone 7a summer. The solution is timing, not technique: plant in early spring and again in late August, harvest the leaf crop during the cool windows, and let the summer gap stand.

Can I grow mint indoors in winter?

Yes. Per Clemson HGIC, mint can be "brought indoors in fall" and will continue growing on a sunny windowsill. A south-facing window provides adequate light for mint, which is less demanding than basil in terms of light intensity. Mint will go semi-dormant in low-light conditions but will regrow when moved back outdoors in spring.

Is parsley a perennial or an annual?

Parsley is a biennial: it grows vegetatively in year 1, then flowers, sets seed, and dies in year 2. Per Penn State Extension, "most gardeners treat parsley as an annual" by replanting each spring. In zone 7a, plants started in May often overwinter and provide a second season of leaf harvest the following spring before bolting.

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Sources

1. NC State Extension Plant Toolbox &mdash; <a href="https://plants.ces.ncsu.edu/plants/ocimum-basilicum/">Ocimum basilicum (Basil)</a>.
2. Cornell Cooperative Extension &mdash; <a href="https://gardening.cals.cornell.edu/lessons/vegetables/basil/">Basil</a>.
3. Cornell Cooperative Extension &mdash; <a href="https://gardening.cals.cornell.edu/lessons/vegetables/basil-downy-mildew/">Basil Downy Mildew</a>.
4. Penn State Extension &mdash; <a href="https://extension.psu.edu/herb-gardening">Herb Gardening</a>.
5. NC State Extension Plant Toolbox &mdash; <a href="https://plants.ces.ncsu.edu/plants/coriandrum-sativum/">Coriandrum sativum (Cilantro)</a>.
6. Oregon State University Extension &mdash; <a href="https://extension.oregonstate.edu/herbs">Herbs</a>.
7. Clemson HGIC &mdash; <a href="https://hgic.clemson.edu/factsheet/mint/">Mint</a>.
8. Xerces Society &mdash; <a href="https://xerces.org/endangered-species/species-profiles/native-pollinators/black-swallowtail">Black Swallowtail</a>.
9. Johnny's Selected Seeds &mdash; <a href="https://www.johnnyseeds.com/growers-library/vegetables/cilantro/growing-cilantro.html">Growing Cilantro</a>.