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Cold Frame Method


The plants are cactus seedlings wrapped in shade cloth. This will protect them even more for the winter in the cold frame. They also share space with local rodents, so the shade cloth prevents the seedlings from becoming winter time snacks.

The cold frame is still open, and is is clear the see that this is a very low tech device. Under the seed trays the ground is covered in broken bits of old side walk. They let moisture from the ground come into the air inside the cold frame. They have to be kept open until just before the snow comes so moisture does not build up inside. Then in the spring they are opened again as soon as the snow melts off of them.


The cold frames are simply wooden boxes with lids covered in plastic. They let a lot of cold air inside and are not air tight. The key is that snow covers them for the winter, and they are deep enough that the plants sit below ground level.

It is still close to freezing at night, but it will start to warm up soon. I scattered Misquito Beater over the outdoor cacti today. This will provide a lot of prevention when soil flies or scaria flies start to hatch this spring. In case there are any eggs present on or around the cacti. This is especially important for seedlings and pots containing seeds that could germinate this spring. Adult cacti usually have few problems with these small flies, but I think it helps protect adult Pediocactus plants too.

The cold frames are all open and the snow has melted. The cacti are now getting direct sun and full exposure all weather conditions.

The snow has melted enough to open 2 of the 4 cold frames. The cactus plants look great, and are still asleep. They are gray and shrunken as they should be in the winter. In a few weeks they will start to turn greener and take up water again, if the weather continues to warm up.

We had a blizzard, and this gave the cold frames more than a foot of new snow cover. This will keep the cacti very save if we get some sub zero weather.

Snow is building up on the cold frame lids. Even though it is only a few inches this should help keep the cactus plants safe.

The cold frames are closed again with less than a quarter of an inch on them. Maybe there will be more snow in the next day or so… otherwise I should open them again.

The cold frame lids are wood with clear plastic taped on to them. It is hard to believe this thin plastic held on by tape will support the weight of snow and ice over the winter, but it does. A cold frame doesn’t get any cheaper than this. Now there is no snow, but when the cold frames were opened in freezing conditions one of them cracked. It is as if the cold makes the flexible plastic fragile like glass. I just put some clear packing tape over the cracks and that should get the structure through the winter. Next summer I probably should replace the plastic with some new plastic.

Usually in December the snow comes and covers the cold frames with the cactus plants inside. These cacti stay covered by snow for the whole winter and in March the snow melts letting them have full sun again. This year some rain came and washed all the snow off the cold frames leaving behind very cold weather with no snow cover. I decided to reopen the cold frames and leave them open until some snow returns. The problem with keeping them closed is that the air inside will become moist from the ground; then freeze on the cold frame lid at night – only to melt in the daytime – which allows water to fall onto the cactus plants and then form ice. This would be bad for the plants. Keeping the lids open and letting the cactus plants be exposed to the dry cold air of winter will be safer than letting them get water drips on them.

It is strange to have no snow protection in January, but the cactus plants should still do well.