garden | The Peterborough & Area Master Gardeners

By Marilyn Homewood, Master Gardener

As we look through our seed catalogues on these cold days, it’s time not only to decide on what we are growing but on how we intend to grow it. The choices seem endless! Winter sowing has been covered in a previous blog. I recommend you give it a try. As for indoor seed starting, there is a plethora of ways to do it. Discovering which works best for you can make the difference to a successful season.

A single flat tray (often called a 1020) or half tray is a traditional way to start seeds. The tray is filled with your chosen medium (be it seedling mixture, coconut coir or potting mix). Seeds are planted in rows in the flat, the medium moistened and set to germinate. Once the seeds have germinated and have developed at least 2 true leaves, the seedling is “pricked” out of the mixture and potted up into a larger container. Pricking out is the term for holding onto a leaf (never the stem!) and gently teasing the seedling out of the potting mix. Pros – single tray saves space, easier to keep moist due to the larger volume of mix. Good for seeds with uneven germination rates such as larkspur. You just prick seedlings out as they are ready. Cons – 2 step process is more labour intensive. Some types of seeds that are sensitive to root disturbance (poppies, zinnias) dislike being tugged out and usually do not do well once transplanted.

Row Trays

These trays are divided into 20 rows. Using a row tray is similar to the open flat in that seedlings are pricked out and potted up. But this system uses much less soil mixture. This tray is commonly used for very tiny seeds that are difficult to handle such as snapdragons. Seeds are just carefully poured onto the seedling mixture and the trays watered from below. Pros- easier method when dealing with small seeds, germinate faster due to smaller amount of soil mix. Cons – more labour intensive, prone to drying out quickly due to smaller amount of soil. Not recommended for varieties that dislike root disturbance. Must also use flat bottom tray as rows trays are too short to sit in a 1020 tray.

Cell Trays

These trays are divided into “cells” that hold growth medium and one seedling. Seed is sown into each cell. Cell trays come in a variety of sizes 50, 72, 128, 200 cells etc. The 72 cell size is the most common. The choice of size is usually dictated by the type of seed sown. For example, I use 128’s for my lisianthus seeds as the seedling is very tiny for a long time. Pros – one step, easy to keep track of how seedlings are doing, water well from bottom

Cons – May need a number of sizes depending on varieties grown, roots of seedlings with a long growth period tend to start circling in cell, this may cause production difficulties once transplanted.

You may not need 72 seedlings of the same variety and do not want varieties that germinate early to stay under the humidity dome until all have germinated.

To address this problem, I use a variation on the 72 cell tray. Instead of using a tray for each variety, I have propagation inserts that can be separated in 9 or 6 cells units. I still plant 72 cells total of more than 1 variety, all placed in a single 1020 tray under a humidity dome. When one variety germinates, I can remove it and put it under the grow lights. This avoids the germinated seedling from developing fungal disease which is fatal (“damping off”). This method lets me successfully germinate different varieties in a limited space.

Soil Blocking

This is a method that compresses wetter soil mix into free standing blocks which are then seeded, germinated and grown on. The blocks are placed on flat trays with lips in order that the blocks can be carefully watered. Seedling roots are naturally air pruned in soil blocks. Plants with long growth periods benefit from the air pruning as do varieties that dislike root disturbance. Pros – No use of plastic!! Despite carefully washing and reusing my trays, each year there are a few casualties that can no longer be used. Soil blockers are a one- time purchase. Seedlings are air pruned and never develop circling roots hence make more resilient transplants by reducing transplant shock. Cons – initial soil blockers were spring loaded and hand held. Can be hard on hands to use. Newer blockers (Swiftblockers) can make an entire 1020 of blocks. These are stainless steel and are heavy to use. There are now half size versions available which are more affordable and easier to handle. Blockers are available in different block/cell sizes. Soil blocking is messy. The mix must be relatively wet in order to compact it. The watering of blocks is a little tricky as blocks can not be left in standing water as they will fall apart.

Winnstrips

This is a hybrid concept between cell trays and soil blocks made from heavy duty plastic. Made in 50, 72, 128 sizes, Winnstrips have air cells throughout the tray and each planting cell has 4 air slits to allow for air pruning. Pros – Not as messy as soil blocks but with the air pruning benefits. Good for varieties that do not like root disturbance. Made from a polypropylene material that is very durable and can be recycled. Cons – trays are heavier and use a great deal of potting mix.

No matter what method you use, remember to have fun!

Resources

Understanding Seed Trays: My Favorite Seed Starting Trays to Use for Flower Farming

‘Garden Jeopardy’ Seed Starting Edition

By Marjorie Vendrig, Master Gardener in Training

Five years ago I moved from a large rural garden outside Ottawa to a small urban lot in downtown Peterborough. One of the biggest changes in my gardening practice was making the switch from large, multi-bin composting to a single, small, black plastic bin. Over the years in my Ottawa garden I had developed a good system for adding kitchen and garden waste, turning the compost, adding leaf mulch, then spreading the compost over the gardens. Here in Peterborough, my small plastic bin was productive on a smaller scale but the raccoons, bunnies, and rats managed to chew through the plastic and serve themselves. It was more of a mess than a benefit. They defeated me. Thankfully, the municipal kitchen waste program kicked in about the time the racoons moved in, giving me a reasonable alternative for kitchen waste. My garden wasn’t getting much benefit except for the fall leaves that I mulched and put over the beds.

I realized that I really miss composting and I would prefer to be putting my own food scraps back into my garden. I started looking into composting systems for small spaces and came across bokashi composting. It’s not really composting, rather a fermentation process, and described as perfect for small spaces. Sometimes called a ‘pre-compost’ process, the fermented results are added to worm compost or outdoor compost where decomposition is completed. It’s also anaerobic so there’s no need to turn the compost or layer materials. The process is fairly fast, about two weeks for the initial fermentation step. Any kitchen waste, including meat, cheese, oil, can be added. Bokashi is a Japanese word meaning fermented organic matter; the practice originated in Japan.

The anaerobic fermentation process requires an accelerator, something like a starter for sourdough baking. It is often referred to as ‘bokashi bran’, the bran inoculated with microorganisms – fungi, lactobacteria, phytobacteria. It’s easy enough to put together a homemade system with a few 5-gallon buckets – one with a tight sealing lid – and other household items. One bucket should have holes drilled in the bottom; this bucket is placed inside the other; the holes allowing any moisture from the fermenting food to drip into the bottom bucket. Fill the top bucket with layers of small 2 – 3” kitchen scraps and bokashi bran until the bucket is almost full, cover and press with a layer of waxed paper, a cloth, or even some foam before sealing the bucket with the lid and leaving for a few weeks to ferment. After about one week some white mold with develop, after two weeks the bucket will smell like pickles and the fermented material can be buried in the garden about 6-12”deep. It will decompose fairly quickly in the garden and planting can be done around the fermented trough after a few weeks. Alternatively, it can be added to the compost heap or even into a large tub of soil indoors where it will continue to decompose. Any liquid – the ‘tea’ in the bottom bucket can be added to the compost or garden as well.

Bokashi bran is widely available online and at some garden centres; it’s also possible to buy a kit that includes bran, several buckets, and instructions. The buckets in the kits often have a tap and reservoir so the ‘tea’ can be collected at the bottom of the bucket. Like sourdough starter, the bran can be made at home, though some starters work more quickly than others. It’s worth experimenting to test a few products and compare results. I’ve learned that a few cities in western Canada have municipal bokashi programs so it is possible in colder climates. On a large scale, it is also being trialled at Sissinghurst, a famous garden in the UK.