Winter sowing method using milk jug containers - Gardening with Brendan

There’s a lot of gardening columnists and video diarists in America who swear by this method, which is as cheap as it easy to do, and many gardeners there undertake it as a way of getting a head start for the spring the following year. And there’s little in the way or cost or effort involved.

First up you are going to need some empty containers. These can take the form of large milk jugs or cartons, or some big water, fruit juice or soda/ lemonade bottles, or even just a deep plastic container with a lid like the ones fresh fruit, pastries and deli items are sometimes packaged in. Semi-opaque or clear plastic is best as it must be able to let light through and the seeds are highly unlikely to germinate and survive inside dark plastic. Other than that, all you will need is a pair of scissors, some waterproof duct tape, a few seeds and a few handfuls of compost.

So what can you winter sow? Quite a bit apparently, vegetables, herbs and flowers of different varieties. In fact I’ve seen people who have really cold winters sowing all sorts of frost tolerant or cold hardy annuals biennials and perennials. There’s a long list of different varieties people have been trying with some quite impressive results and many vloggers report that tender young seedlings or crops that would have perished in containers or in the open soil with the arrival of the first frosts and snows of winter, actually fared quite well inside their containers.

I’m only trying four different seeds this way for overwintering at this stage: some newly purchased spring onion seeds, and some of the calendula, Iceland poppy and oriental poppy seeds which I collected from the garden over recent weeks. I may try to sow some more when the temperatures drop and the days shorten in December or January and compare the results with the autumn sowings.

Which brings me to when you should do it. Really, you probably shouldn’t be undertaking the winter sowing method until just the winter weather arrives, or just before. Some gardeners sow in late November and December and others wait until January and early February. It’s only October here but I thought I’d get to grips with how it’s done early for later on, and in case anyone else wanted to try it too in the months to follow.

Preparing the bottles: Make sure the bottles you are reusing for this process are food grade plastic containers if you are sowing any type of consumable herbs, vegetables or indeed flowers – i.e. plastic used to store food and drink products like milk, fruit juice, cola, lemonade, yoghurt, cream etc because if they are deemed safe for drink they will be deemed safe for your food.

Method: First up, leave the lids on the bottles, if using bottles, and use the scissors or a different tool to carefully create holes at the base, and to the sides along the bottom perimeter for drainage. Do the same if using plastic food containers. Then, about 3.5 to 4 inches from the base, make an incision and cut around the circumference but leave two or three inches at one corner intact to create a hinge – if you are using milk jugs it’s a good idea to make the corner opposite the handle the hinge. Lastly, remove the lid and recycle – you won’t need the lids for the rest of the process. And that’s the container ready for the next stage.

Filling and sowing: Carefully folding the bottle back on its hinge, fill the bottom part with around 3.5 to 4 inches of pre-moistened good quality, crumbly dark compost and spray or sprinkle a little more water over the top. You want it good and moist but not soaking wet. Pat down the surface of the soil lightly so that it is level and firm enough so that the seeds won’t fall through to the bottom. After that, clean and dry your hands if necessary and then choose your seeds and pour some out carefully. You won’t need too many seeds if, like me, you are growing in 2 litre milk cartons, which I asked a relative to keep for me. Space is limited in the containers and you don’t want to have to separate out hundreds of spindly tiny seedlings weakened by having to compete for light. Sprinkle a few seeds over the surface of the soil and as a general rule of thumb, if the seeds are larger press them a little bit into the soil and cover, but if they are tiny like poppy seeds skip this and just pat them lightly onto the soil surface to ensure contact. Then just give a gentle misting of water and close the container. Dry off the exterior if any water or damp soil has managed to stick to it and then get the waterproof tape and seal around it, making sure there are no air pockets.

Finally, all you have to do is just tuck the containers in somewhere in the garden where they will get some light but won’t get blown over by the wind. The idea is that the containers act like like insulation, a mini greenhouse and keeping the lid off all winter will let some rain or snow in to prevent the soil drying out. You should probably check them every week or so in case they need a little water top up but other that than you can forget about them till spring. It’ll be interesting to check back on them in 2025.