October garden tasks: Northeast and Long Island

This article contains affiliate links. As an Amazon Associate, we earn from qualifying purchases, at no extra cost to you. See our full disclosure.

Where the frost line sits in October

October is when the Northeast splits. In zone 5 (upstate New York, Vermont, New Hampshire, inland Massachusetts), the first frost usually arrives around the start of the month and the vegetable garden is finished or close to it. In zone 7 (Long Island, New York City, coastal New Jersey), the average first frost does not come until around November 7, so October is still a working month with fall greens in the ground. Zone 6 (coastal Connecticut, the Hudson Valley, most of New Jersey and southeastern Pennsylvania) falls in between, with frost typically in mid-to-late October.

Check your own date with the frost date tool and treat it as an average, not a promise. When a frost warning is in the forecast:

• Pick all remaining tomatoes and peppers; green tomatoes ripen indoors at room temperature.
• Cover lettuce, chard and other tender greens with floating row cover overnight; kale, collards, spinach and Brussels sprouts handle light frost and often taste sweeter after it.
• Bring in houseplants that summered outdoors before night temperatures drop toward the 40s, and check them for insects first.
• Dig tender bulbs such as dahlias, cannas and gladiolus after frost blackens the foliage. Penn State Extension recommends letting dahlia clumps dry briefly, then storing them in a cool, frost-free spot. See our guide to overwintering dahlias.

Plant garlic

Garlic is planted in fall for harvest the following July. Cornell and Penn State Extension both treat fall as the main planting season, timed so cloves root before the ground freezes but do not push much top growth.

• Zone 5: early to mid-October.
• Zones 6–7: mid-October into early November. On Long Island there is no rush.
• Allium leafminer: this pest is now established in Pennsylvania, New Jersey and New York. Penn State Extension advises planting garlic later in the fall where it is present, so emerging shoots miss the adults' fall egg-laying flight.

How to plant: break bulbs into cloves just before planting, keep the largest cloves for seed, and set them pointed end up about 2 inches deep and 4–6 inches apart in loose, well-drained soil. Buy seed garlic from a garlic grower rather than using grocery-store bulbs, which may carry disease or be varieties suited to a different climate. Once the soil starts to freeze, cover the bed with a few inches of straw (not hay, which carries weed seed).

Plant spring bulbs, trees and shrubs

Spring bulbs go in once soil at 4 inches has cooled below about 60°F, as covered in the September guide. In zones 6–7 that means most of October. In zone 5, aim to finish by mid-to-late October. October Gardening Tips gives the standard rule:

• Plant bulbs about three times as deep as the bulb is tall, pointed end up.
• Plant in groups instead of single rows. Clusters look better in April and are easier to fertilize.
• Water after planting so roots start growing before the ground freezes.
• Where deer and squirrels are a problem, daffodils are the safe choice. Tulips and crocus are favorite foods. See how to plant bulbs.

Trees and shrubs: October is still a good planting month across the region. Per UMass Extension, fall-planted stock keeps growing roots while the soil stays warm. Container and balled-and-burlapped plants can go in through October. Some species, including many oaks, birches and magnolias, are known to establish poorly when planted in fall, so plant those in spring. Water new plantings deeply every week that rain falls short, right up until the ground freezes.

Last lawn feeding and mowing

September is the main fall fertilization month for cool-season lawns. In October, the jobs are a final, lighter feeding, keeping up with mowing, and dealing with leaves.

Know your fertilizer cutoff. Northeast lawn fertilizer is regulated by date:

• Suffolk County (Long Island): lawn fertilizer may not be applied from November 1 to April 1, per Suffolk County's Healthy Lawns, Clean Water program. October is the last legal window.
• Rest of New York State: the state Nutrient Runoff Law bars lawn fertilizer from December 1 to April 1 and restricts phosphorus unless a soil test shows a need.
• New Jersey: the state fertilizer law sets a winter blackout that begins November 15 for homeowners, per NJDEP.

If the lawn is still green and growing, a moderate application of slow-release nitrogen in early-to-mid October supports root growth and earlier spring green-up. Purdue's turf program has shown that fall nitrogen feeds roots rather than top growth on cool-season grass. Never spread fertilizer onto pavement, and sweep up any granules that land there.

Mowing: keep cutting at your normal height (3–3.5 inches for most Northeast lawns) until the grass stops growing. Purdue's turf team advises against dropping the mower to scalp the lawn for winter.

Leaves, cleanup and soil testing

Shred leaves instead of bagging them. Research summarized by Michigan State University Extension found that shredding leaves into the lawn with a mower does not harm turf, as long as grass blades still show through afterward. Heavier drifts can be shredded and used as mulch on vegetable and perennial beds or added to the compost pile.

Clean up selectively.

• Remove and throw out (do not compost) diseased foliage: tomato and squash vines, peony leaves with botrytis, rose leaves with black spot, and fallen fruit.
• Leave healthy perennial stems and seed heads standing. Ornamental grasses wait until early spring, as the September guide notes. Hollow stems and leaf litter shelter overwintering beneficial insects.
• Pull spent annuals and weeds before they drop seed.

Test soil now. Fall is a good time to sample because labs are less busy than in spring, and lime needs months to raise pH. Cornell Cooperative Extension recommends taking several cores from each area (lawn, vegetable bed, foundation planting), mixing them in a clean bucket, and sending one composite sample per area. The UMass Soil and Plant Nutrient Testing Laboratory accepts samples from home gardeners. Our soil testing guide walks through the steps.

Dividing perennials and fall cover

Late summer and fall bloomers (hostas, daylilies, coneflower, black-eyed Susan) can still be divided in early October in zones 6–7. Stop about four to six weeks before the ground usually freezes so divisions can root. In zone 5, wait until spring. Leave fall bloomers such as asters and mums alone until they finish flowering, then divide them in spring.

For vegetable beds that are finished, sow winter rye as soon as each bed is cleared. It is the cover crop that still germinates in cool October soil. Rye holds the soil through winter and gets turned under or cut in spring. See green manure cover crops. Beds that stay bare should at least get a layer of shredded leaves.

Common mistakes

Frequently asked

Is it too late to plant grass seed in October?

In zone 7 (Long Island and the NYC metro), the September guide gives October 1 as the practical overseeding deadline. Seed sown later in October may germinate, but the seedlings often are not tough enough to survive winter. In zones 5–6, the window has closed; dormant seeding in late fall or overseeding in spring are the fallbacks.

When should I mulch garlic?

Put straw on after planting, once the soil begins to freeze. Cornell and Penn State both recommend a straw mulch over winter to moderate soil temperature and limit heaving. Pull it back in spring if the soil stays cold and wet.

Should I cut back perennials in October?

Only diseased plants and anything that turned to mush after frost (hostas, for example). Leave healthy stems, seed heads and ornamental grasses standing until spring. They catch snow, shelter beneficial insects and feed birds.

Can I still plant trees in October?

Yes, for most container-grown deciduous trees and shrubs. Per UMass Extension, roots keep growing until the soil gets cold. Plant species that are known to be poor fall transplanters, such as many oaks and birches, in spring, and keep everything watered until the ground freezes.

Sources

1. Plan on Garlic This Fall, Cornell University School of Integrative Plant Science
2. Plant Garlic Late to Avoid Allium Leafminer, Penn State Extension
3. October Gardening Tips, UConn Home and Garden Education Center
4. Fall Planting for Trees & Shrubs, UMass Extension
5. Healthy Lawns, Clean Water Fertilizer Reduction Program, Suffolk County, NY
6. Fall Fertilization, Purdue University Turfgrass Science
7. It's not too late to mulch fallen leaves into lawns, Michigan State University Extension
8. How to Take a Soil Sample, Cornell Cooperative Extension Rensselaer County

Read next