Season Extension and Crop Planning

Around January every grower hunkers down to their desk, and embarks on the process of collating all their sales figures for the year into a crop by crop analysis of how the growing season went. This process can be quite an arduous one, especially as a market gardener, unlike some large growers who specialise in a few crops for wholesale, can have over 40 types of vegetable and fruit he/she grows. These all need some kind of analysis as to what was expected in the cropping forecast compared to the actual yield recorded. In this blog post I am going to run through the process briefly of how I go about it all and how this relates to methods of season extension we employ to make the most out of the season.

First off, look back at the year previous and get figures for weekly yield (and income), for each crop and compare this with the forecast you made. This allows you to see if the process you went through to calculate yield per square metre was accurate and also where your gaps in supply were and how you might go about fixing them. Of course sometimes weather, field conditions and pests will of caused your yield for a crop to drop below that which was expected, (I had a bit of a disaster with my second main crop of spinach this year for instance, and you’ll see that reflected in the figures). Otherwise they should be as predicted because you went through this process to get there which is:

  1. Decide on how much to grow of each crop, a spreadsheet with yield per week for each crop and expected revenue. This is basically your business plan/year forecast without the expenditure taken into account. Some new growers starting out might not take the time to do this stage, but you need to make sure what you’re forecasting actually adds up to some kind of livelihood at the end of the year’s grand total!
  2. Create a production calculator, really hard to do if you haven’t worked on a farm/ grown vegetables regularly, as you need to be able to have a reasonable guess at a per meter square yield for each crop, plus grow back time if it’s cut and come again. Once you say I want 10 kg of spinach a week from my plot, you need to know how much a bed is going to yield each week and thus how many beds you need to grow and also how long this crop is going to yield. Below is mine for this year based on updated figures from the year previous. You now know how many beds you need at any given time of any crop to meet your targets.

3. Make sure you’ve got enough space on your land for your projected plan. I have standard size beds so it’s easy to work out, you may be able to follow one early crop with another later crop which obviously needs to be carefully worked out. I do this on a A4 sheet with all the beds marked in blocks of 15 to help with crop rotation (something you do in organic systems to break pest and disease cycles so they don’t build up the same spot).

4. Calculate sowing dates and amounts of plant modules/seed directly sown to the bed you’ll need. All my beds are the same length and width so you get to know how many plants you’ll need to sow for say a bed of lettuce or kale. I have this printed out and a copy up at the site just in case I need to double-check it when sowing or planting. Again another spreadsheet!

5. Work out days to maturity from when you first want to be cropping a crop such as salad. This again is much easier once you’ve done it one year and kept accurate records of when you actually had sown the seeds for your salad as opposed to when you said you were meant to in your sowing calendar. If you look at the table above I’ve got three different entries for salad one for the start when temperatures are cooler and light levels less, so the crop takes longer till it’s ready, one for summer and one for autumn. Knowing this information means you can be on time and target with your actual yields compared to your forecasted ones.

5. Put this all down in a calendar that is easy to read, at first I started with using a spreadsheet for sowing dates, but I found this too hard to wrap my head around in terms of space relating to time in my mind. So I opted for this approach below

I colour code to differentiate between the plan and my actual records of what was done when (plan in pencil and coloured pencils, actual in pen or coloured pens).

You then have to total up the amount of beds you’re growing in total and calculate the seed you need to order for the year. You want to use up all the seed you’ve ordered each year ideally as germination rates drop dramatically with some vegetables and the fresher the more likely you’ll get all the plants you need to fill the space designated in your plan.

Of course getting seeds to germinate requires the right temperature and moisture, light plays a part but most will germinate in low light levels. To do this you’ll need a heat bench in our northern climate, especially for tomatoes if you want to be harvesting them in July (you do as everyone goes on holiday in August!).

The way I guarantee I can get the early crops planted once they’ve germinated is to cover the area I am going to plant in water-proof black plastic mulch. This kills off the plant matter already there allowing for a clean dry-ish area of ground you can then go in with a broadfork (see previous blog post), to loosen and a small two-wheel tractor before the land is really dry enough to go on with bigger machinery.

Cover them with a fleece and watch out for slugs and with any luck you’ll get some leaves in June and even May if the weather is favourable!


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