The last (and only) time I tried growing parsnips ("Harris Model") a couple of years ago, they ended up much "fatter" than the parsnips I've typically seen in the store and in pictures. Instead of being just a bit bigger than carrots, these were about 3-4" diameter at the top, and had a tough woody core. The core was inedible and removing it made cooking them a hassle. I regarded the crop as a "loss"; nobody wanted to cook or eat it.

I followed directions seen in various places: direct seed in spring (late April) and harvest after some frosts (around Thanksgiving -- mid-November). Some research I did afterward indicated that I may have given them too long of a growing season and should have harvested them earlier. (I.e. maybe they were overmature?) The tops were at least 3' high, which is more than I've seen elsewhere. Was it too much fertility (i.e. an overdose of horse manure)?

What caused this problem and how can I prevent it when I try again next spring?


2 Answers 2


The tough woody core would almost certainly have been caused by:

  1. insufficient moisture - the soil should never be allowed to dry out - although, of course, some varieties of parsnip have a good deal more core than others; it is worth looking through the seed catalogs for a variety with very little core (the one I use is Tender and True, but I don't know if it's available in the US);

  2. leaving them in the ground too long, as you suggest. Although the standard advice is to leave them in the ground until after the first frosts, I've found that when I do this, they become woody, like yours, and are tunneled by carrot fly. I've now started lifting both carrots and parsnips in mid-Autumn and, although the parsnips are not quite as sweet, they are not at all woody, and carrot-fly damage is minimal.

Their over-large size is probably down to the horse manure, resulting in an over-fertile soil coupled with their prolonged stay in the ground. When sowing carrots and parsnips, I've found it better not to add any manure at all, and to sow on a plot that I've manured the previous year.

  • Thanks. I'll try them again next year with less fertility and a shorter stay in the ground.
    – bstpierre
    Aug 7, 2011 at 17:50

Q. Fresh or aged (well rotted) horse manure?

"bstpierre" A. Well rotted.

Q. Is the soil well cultivated ie Is the horse manure dug at least a spades depth into the ground?

"bstpierre" A. That bed was fairly well mixed to about 18".

Q. Do they get enough water, especially early on & during hot, dry spells in the summer months?

"bstpierre" A. They got plenty of water.

Q. Also during the hot summer months do you mulch them with something like a couple of inches of compost?

"bstpierre" A. No mulch.

Q. Have you tried sowing at 2 week intervals from later April to end of May, just to see if the later sowing works better in your environment (growing conditions)?

"bstpierre" A. I only tried growing them once, but the 2 week interval suggestion would be an interesting experiment.

Then the only couple of things I can think of suggesting at the moment are:

  1. Mulch during the hot summer months, as I've learnt since living here in the US, the heat in the UK doesn't come close to what is experienced over here, therefore mulching tends to be very important, especially during the summer months

  2. Go with the 2 week interval sowing experiment. I think you might discover the shorter growing season works better for your growing environment.

And to answer the original questions:

Q. Why were my parsnips fat?

A. I believe it's most likely a combination of too much fertiliser (soil might be too fertile), too much water (causing some swelling to occur) and being left in the ground too long.

Too much water (during the summer months) = More than, "Water thoroughly once a week in periods of extended dry weather to keep growth from slowing in summer", via University of Illinois Extension. Sorry, could find similar information on the University of New Hamsphire Cooperative Extension site or neighbouring state Extension Office sites.

Q. Why do my parsnips have a woody core?

A. I believe it's most likely caused by them being left in the ground too long, try shortening your growing season by sowing later or experiment by sowing at 2 week intervals to see what works best for your growing environment.

  • Thanks. Regarding mulch, temps in NH are not like MO. If we hit 90F, it's a constant topic of conversation... two or three days at 90 and it's a state of emergency.
    – bstpierre
    Aug 7, 2011 at 21:26
  • @bstpierre, definitely sounds much more like the UK, except the UK goes into melt down when it hits +80°F :) Example: Mercury hits almost 29C as Britain burns
    – Mike Perry
    Aug 8, 2011 at 16:25

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