I used a shovel (having misplaced my spading fork) to dig carefully under the centre of the plant where the tubers grow. As the photos show there was a nice mixture of large and medium sized tubers.
The total harvest from a bed that used about 65 square feet of garden space was about 25 pounds. The variety of Sweet Potato that I grow is called Georgia Jet. Now for the comparison with Yukon Gold, a regular potato variety, that was growing in an adjoining identical size bed. The Yukon Gold which was harvested a few weeks ago weighed in at 45 pounds – the clear winner this year. The yields depend on many factors. I find that other potato varieties are more productive than Yukon Gold, both beds were nibbled on by deer early in the season and Sweet Potatoes are highly dependent on the heat we receive. For example the yields of Sweet Potatoes in the last two summers which were much cooler were abysmal.
I find it interesting to compare this with the yield of soybeans that are currently being harvested in fields all around the area. A good crop of soybeans is about 45 bushels per acre which at 60 pounds per bushel works out to about one pound for every 16 square feet or about four pounds for 65 square feet of growing area.
To be fair, this is in no way a scientific experiment as it only compares one dimension. If one were looking for a more exact comparison it would be useful to compare moisture content or protein content. For the present I am happy to know that a huge volume of fresh wholesome food can be produced in relatively small gardens. This is a subject that I will be revisiting.
The Sweet Potatoes were planted about two feet apart on a raised bed. The bed was covered with straw which prevents the vines from rooting at every node (where the leaves join the stem). The objective is a central group of large tubers rather than pencil-thin tubers at every node.
Unlike regular potatoes where the tuber is planted in the garden, Sweet Potatoes are started by planting either shoots (called slips) or vine cuttings in the garden. Slips can be purchased by mail order (one Canadian source is Mapple Farms) or can be grown by placing tubers in water or moist peat moss 4 to 6 weeks before slips are required for the garden. The key to successful growing of Sweet Potatoes locally is choosing a variety that will produce a good crop during our short summer. DO NOT try to grow slips from a tuber purchased from a supermarket. The varieties found there generally require 120 days to produce a crop compared to the 90 or so days of hot weather available to us. Georgia Jet is by far the best variety that I have found for the local climate, having excellent taste and producing many medium and large sized tubers.
Tubers should be dug by mid-September and should be cured right away. Curing requires a space that can be maintained at about 30 to 32 C with high humidity for a week. This allows the skin to toughen and slows down the rate at which the tubers will dry out. Tubers can then be stored at temperatures between 13 and 18 C (much warmer than the storage requirements for regular potatoes). A properly cured tuber can be stored for a year or more and can be used to start next year’s crop.
Remember to keep an eye on the forecast low temperatures and prepare to cover your tomatoes, peppers and eggplant. The cool-weather plants such as kale, Swiss chard, parsley and salad greens will continue happily for a few more weeks.
One vegetable that has responded well to cooler temperatures is broccoli. I cut the first broccoli heads with a fairly short piece of stem. The broccoli plant will then produce secondary heads that will grow from the node where the leaves join the main stem. Growth may be slow if we get a lot of hot summer days but will speed up considerably in cooler fall weather producing until a very hard frost. Some of the older varieties are much better at producing secondary heads than are new modern hybrids that are bred to produce one large head for commercial harvest. As the following photo shows lush secondary shoots are ready for harvest and were dinner last week.
I had the privilege to participate in the Ag Awareness activity at the Carp Fair on Friday morning as nine classes of Grade 4/5 students listened to presenters at nine different stations ranging from beekeeping, making maple syrup, raising pigs and of course growing vegetables. After interacting with 400 kids, parents and teachers over the course of two and a half hours I became convinced that no amount of pay is enough for our teachers!
I was very pleasantly surprised by the number of children who have had exposure to growing vegetables and are very much aware of the benefits of growing food in their own garden. Responses to why it is beneficial to grow our own food even though it involves a lot more work than going to the grocery store, included:
- The food is much fresher
- There are no pesticides or chemicals
- It is much closer and requires less transportation
Plan to take some workshops with the Almonte Library and the Neighbourhood Tomato next spring as gardening experts share their experience with growing vegetables in our area.
The Great Veggie Grow-off
We are rapidly closing in on the final weigh-in on Saturday October 10. Remember the Food Bank and bring your baskets of surplus produce to the Lanark County Food Bank at 5 Allan Street in Carleton Place and make sure that it is weighed and credited to Mississippi Mills as we compete against Carleton Place and Beckwith in the Great Veggie Grow-off. The Food Bank is open Monday 5pm to 7 pm, Tuesday 9am to 1pm, Wednesday 7 to 9 in the evening, Thursday 9am to noon and Friday 9am to noon. Try to drop it off early in the week if possible – greens in particular if stored over the weekend when the Food Bank is closed do not look very appetizing by Monday. One other option is drop off your produce at the Almonte Library during regular library hours and volunteers will transport it to Carleton Place.