Cobham Improved Marrow

Family: Apiaceae Vegetable

Sweetly earthy and richly aromatic, Cobham Improved Marrow develops long, tapered roots with a creamy, smooth interior that tastes like a gentle blend of garden sweetness and roasted nuttiness.

The flesh is notably tender and fine-grained, holding its appeal from fresh harvest through oven-browning and hearty mash-style preparations. Grow this dependable 110-day parsnip for a satisfying, full-bodied flavor that shines in roasts, soups, and velvety sauces—an heirloom-worthy staple for the home garden.

Light: Full SunMaturity: 110 DaysHabit: Taproot

Botanical illustration of Cobham Improved Marrow

Planting schedules and alerts are optimized for Columbus (Zone 6b).

Crop Dates

Milestone	Date
Start Indoors	Direct Sow
Last Frost	Apr 25th
Transplant / Sow Outdoors	Apr 25th
Harvest Begins	Aug 13th
Harvest Ends	Oct 16th

Crop Details

Trait	Value
Days to Maturity	110
Sun Requirements	Full Sun
Growth Habit	Taproot
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	50
Min Soil Temp (°F)	45
Min Night Temp (°F)	28
Harden Off (days)	Not Required

Culinary Notes

Chef's Note

Cobham Improved Marrow brings a gentle, sweet earth that roasts into a nutty perfume—its fine-grained tenderness helps it mash silky instead of turning fibrous or watery. When you let it brown hard in the oven, the flavor turns from garden-sweet to deeply savory, making it a natural partner to butter, cream, and pork.

Best Uses

high-heat oven roasting until deeply browned at the edges
velvety parsnip soup or purée (works silky without stringiness)
sheet-pan parsnip + thyme/garlic-style roasting alongside stronger proteins
mash-style preparations where it stays smooth and sweet rather than watery

Flavor Profile

sweetly earthy richly aromatic tender, fine-grained flesh roasted nuttiness with a creamy finish

Kitchen Pairings

brown butter thyme garlic heavy cream nutmeg pork (roast or sausage)

Frequently Asked Questions

Why are my Pastinaca sativa (parsnip) roots developing dark, spreading lesions or cracking near the soil line, and what should I do?

This is often a mix of fungal rot from overly wet soil plus secondary issues where roots are bruised or crowded. Keep the bed evenly moist but not soggy, avoid working the soil when it’s wet, and thin seedlings early so roots don’t rub and split. If you see infected tops, remove affected plants promptly and don’t compost the debris.

How often should I water parsnips during the main root-filling stage (mid-summer to fall)?

Water deeply about 1–2 times per week, aiming for consistently moist soil 6–8 inches down rather than frequent light sprinkles. Once roots start swelling, let the top inch dry slightly between waterings to prevent root rot, then water again so the entire root zone rehydrates. Mulch with a thin layer of straw or shredded leaves to reduce drying cracks.

How can I tell when Pastinaca sativa (Cobham Improved Marrow parsnips) are ready to harvest?

Harvest at roughly 110 days from sowing, when roots are firm and reach a usable size (typically thick, straight roots with a tapered tip). You can start pulling a few earlier for smaller roots, but main harvest is usually in cool weather—parsnips often taste sweeter after light frosts. If tops start yellowing and the roots feel fully developed, it’s time to lift them before the ground warms up.