Jennifer Schultz Nelson
Extension Educator, Horticulture
Despite the recent 80 degree weather, we still consider the official frost free date for central Illinois to be around Mother's Day. It is awfully tempting when we see all the warm weather plants available in stores already—bedding plants, tomatoes and peppers to name a few. But there is still a strong chance that we will see a frosty night or two. There is a saying that says "if you plant early, you plant often".
One way to satisfy the urge to garden this time of year is to do some spring cleaning of your houseplants. This is the perfect time of year to trim, repot, and divide houseplants. It's also a great time to evaluate any special garden plants overwintered in the house or garage.
Many of my houseplants become somewhat leggy indoors, even those that I keep under supplemental lighting. I resist the urge to cut these plants back until the increased sunshine of spring returns. Most houseplants' growth slows or stops altogether during the winter months.
Pruning or trimming houseplants encourages new growth on the plants, and doing so during the dimly lit winter months does nothing but encourage weak, spindly growth.
It's a good idea no matter what time of year it is to remove dead and dying foliage from houseplants. Somewhere I once read that a "yellowed leaf never turns green again". This is very true. Sometimes leaves that look a bit pale can be revved up with a dose of fertilizer, but once a leaf has turned totally yellow it is a goner.
Spring is the perfect time of year to repot plants that need larger living quarters. When repotting, choose pots that are only an inch or two bigger than the existing pot. Choosing a pot that is dramatically larger will result in a large volume of soil that doesn't contain roots. When watered, this large soil volume stays wet for extended periods because it is not populated with roots to take up the available water. This may encourage root rots.
When repotting, use a high quality soilless mix which drains well. Soilless mix consists of an organic component, typically peat moss or bark, plus a mineral component such as vermiculite, perlite, and/or sand. These mixes are lightweight and allow for good drainage and healthy root growth. Mixes containing soil are typically too heavy and retain too much moisture in pots, contributing to root rots.
My personal experience with inexpensive potting soil resulted in the demise of my amaryllis collection I had amassed during college. As a poor starving graduate student I repotted my bulbs using a "potting soil" that was on sale and it drained very poorly. The excess moisture around the bulbs resulted in them rapidly deteriorating and rotting. Needless to say I learned my lesson and have never purchased that type of potting mix again.
As new growth begins in the spring it is the perfect time to propagate many houseplants. Dividing or taking cuttings are common ways to propagate houseplants. Call the Master Gardener Help Desk at (217) 877-6872 for information on the best methods for particular plants.
If you have taken the time to overwinter tender bulbs or tropical plants this winter, now is the time to assess whether your efforts were successful. Tender bulbs should be firm, not shriveled or mushy, and dormant or semi-dormant plants should be showing signs of life.
Despite my own advice, I have moved most of my houseplants and tender tropicals outside to take in the gorgeous weather we've had. I swear my plants breathed a sigh of relief as I brought them out into 80 degree temperatures!
There is of course the risk of frosty temperatures returning. If that occurs I will need to get these plants into a protected area or cover them. But until then I will enjoy the gorgeous warm spring weather.