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Nursery Notes: Indoor plants still need moisture in the winter

Place some of your plants in the kitchen or bathrooms to help give them more humidity, says columnist Evan Davies...
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Evan Davies owns Beltane Nursery at 2915 Highway 3 in Erickson.

Moderate winter weather is still leaving me with a chill when I come in from outside. I think it is the wind.

A few days ago, I seeded the pansy and viola crops in the greenhouse. They usually mature in 14 to 15 weeks, so if we have good sunny weather their first blooms will still be a week late for this year’s early Easter. Not the ideal way to start the new year off but it’s not like they are Easter lilies, which tend to have little to no value after Easter. I can run the greenhouses a few degrees warmer, use supplemental lighting and feed the seedlings a little bit earlier. This should help them grow just that much faster to start.

While greenhouses tend to have higher humidity at this time of year, which is helpful in germinating seedlings, the indoor climate of our house can have a desert-like humidity. Our home’s relative humidity is sitting between 25 and 30 per cent, with very dry air. If you have tropical houseplants or a leftover poinsettia, they are likely drying out on a very regular basis. If possible, place some of your plants in the kitchen or bathrooms of your home to help give them more humidity.

It is important to water them regularly when they are dry. I like to sit the potted plants in a large bowl of warm water (or the sink) for a few hours to saturate the root ball and then let them drain. Indoor tropical plants enjoy warm temperature and high humidity. Many commercial specimens began life in a greenhouse somewhere in Florida before being shipped north.

On the other side of the spectrum, I keep some old cacti growing in my office space that is kept quite cool (15 C) and fairly bright. They do well there with next to no water over the whole of winter. Basically they have gone dormant but aren’t freezing.

Most indoor plant pests go dormant for winter too. This has to do with the shorter day length, same as what makes your poinsettia start to flower through fall. Last fall, I had noticed a few spider mites on a newer palm tree we had acquired for our home. There was not enough to worry about at the time — no webbing was showing and no leaf damage was noticed. It was late September and the natural day length was short enough I knew they would be shutting down for winter.

However, these little critters are responsible for about a third of the insect damage to agricultural crops worldwide, so we want to take them seriously and eliminate them before they spread. You can kill them off with three separate applications of Safer soap or any other miticide, but you have to get the timing right. When you notice them moving again later in spring, place the plant in the shower and spray them down well both on the upper and undersides of the leaves with the soapy water. Let that set for an hour and then shower them off. At room temperature, the next generation will hatch out from remaining eggs about five days later. You need to reapply the soap treatment again and wait for another five days for a third spray. This ensures that there are no further offspring to start the problem all over again.

The tiny mites can spread by crawling, hitchhiking on people’s clothes and outdoors by blowing in the wind. If temperatures are warmer, their life cycle speeds up accordingly. In hot summer weather, eggs may hatch in as little as three days. That is why they can be such a destructive agricultural pest.

Evan Davies owns Beltane Nursery at 2915 Highway 3 in Erickson.