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"I have for years been unable to grow carrots, beets, parsnips, etc. I'm sure the soil is the problem. What do I need to add to it?
Ken, via email
There can be many reasons for problems growing vegetables, including old seed, a shady garden site, greedy roots from trees nearby, past use of broad spectrum herbicides, or acidic soil.
Moss forming on soil in the winter is a sign of acidity, but a soil test is needed to determine how acidic the soil really is. Soil test kits can be had at garden centre.
The ideal soil for most vegetables is pH 6.5. Anything lower than that (lower pH numbers indicate greater acidity) will need lime in fall or spring. The test result will show you how much lime is needed.
One of the best soil enhancers is compost. If you don't have your own compost, you can buy city or commercial compost, or dig in manure. Sea Soil (a composted mix of fish, seaweed and soil) is also an excellent soil amendment. Most garden centres offer Sea Soil in spring.
All help improve the texture of the soil, as well as adding nutrition. Later, less bulky organic fertilizers would also help.
Compacted soil needs to be deeply dug, with compost added to break it up into a texture that roots can penetrate. Rocks and big stones should be removed.
A mulch of grass clippings or straw will help retain moisture in summer. Carrots need a light, sandy soil with very few stones. If you have clay soil, carrots will do better if you build a raised bed with a mix of sand, topsoil, and compost. The germination rate for carrot seed is lower than for many other crops.
The carrot rust fly can be a serious pest. The varieties 'Flyaway' or 'Resistafly' are less prone to infection than most. Covering the row very securely with agricultural fleece keeps the flies out.
Do not sow beets until May, when the weather is warm. Beets need lots of nutrition. Their germination rate is often poor, and can be quite uneven, because several seeds are contained on the outside of each seed-ball. So you have to be prepared to transplant very young beet seedlings from areas where they've germinated into gaps in the row where they didn't germinate at all.
Parsnips also germinate very poorly - only about 65 per cent pop up as seedlings, even from fresh seed. Old seed has an even worse record. Regular soil is fine for parsnips, but it needs to be deeply worked and largely stone-free, because parsnips have very long roots. They need to be sown about April.
With carrot, beet, and parsnip seedlings, slugs can be a major hazard. Later, if they are mulched and stored in-ground for winter, voles can munch their way through whole rows. Randomly placed groups of root vegetables stand a better chance of making it to harvest where voles are active.