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Plant Lady: Potted plants can be tricky if you don’t manage from the ground up

The No. 1 reason people kill their potted plants is overwatering.
The No. 1 reason people kill their potted plants is overwatering. Fresno Bee file

As the manager of around 3,000 potted plants, it is mandatory I know what keeps plants flourishing in this environment. Indoors or out, here are some insights to keep potted plants thriving.

Enhance soil drainage

The No. 1 reason people kill their potted plants is overwatering.

Plant roots need oxygen, and when soils do not dry it creates an anaerobic environment (no oxygen) leading to root rot. Try not to overwater, which is easier said than done.

Because this is so prevalent, the recommendations that follow are meant to allow you to maintain your (over)watering practice, by providing a soil with excellent drainage characteristics.

Why not just teach proper watering techniques? This is very problematic, as each plant has different requirements and signals of under/overwatering. Planting in a loose soil allows rapid drainage, helping ensure plenty of oxygen.

About 85 percent of our plants at the UC Davis Conservatory (including non-succulents) are in a succulent mix. What defines a good succulent mix is the ratio of inorganic to organic material. Most mixes available for purchase are not ideal. They tend to be dense with peat moss/redwood compost (organic material) and low in inorganic matter such as pumice, sand or red lava.

Creating a good succulent mix on your own is easy.

Option 1 – If you water one time a week or less: Purchase any bag of potting soil. Mix in pumice or red lava (sold at most nurseries or rockyards). The ratio is 75 percent potting soil and 25 percent pumice or red lava. Avoid adding sand, as pumice and red lava have more air pockets.

Option 2 – If you water very often (twice a week or more): Follow this proprietary succulent recipe I use. It takes a bit more work because of the specificity, but offers excellent drainage results. The ratio is 60% red lava (5/16-inch size), 14 percent coarse sand, 13 percent peat moss, 13 percent redwood compost

Another benefit to adding pumice and red lava to your mix is the soil volume remains high. Why? Soil with higher concentration of organic matter breaks down, resulting in the shrinking of soil volume over time.

No junk at bottom of the pot

A longstanding garden myth is to place a layer of rocks in the pot bottom before adding soil. The theory is it will be an air pocket for your plant’s roots.

At best this is ineffectual, at worst detrimental. Most pots are designed to allow drainage, being broad up top and narrow towards the bottom. Adding rocks effectively decreases the taper of the pot.

Think of it like this: a wet sponge held parallel to the ground will not drip. The same sponge rotated perpendicular will drip water immediately. Adding rocks to a pot is the equivalent of the parallel sponge. Furthermore, you decrease the amount of space for roots to grow.

Prevent cats from disturbing soil

If you are a cat owner, you know the outcome when they want to “help” you garden. In a more literal sense, they either use your plant’s pot as a litter box or just dig in it . Regardless, they make a mess and harm the plants.

What to do? Make the environment less appealing and harder for them to excavate. I add river rocks or broken terra cotta pots (sharp ends down). This takes up space, making digging difficult. During a talk I gave, someone mentioned a friend would place plastic fork ends upright into the soil. Pass. I don’t want my cats to dig, but I am not looking for impaled felines.

Pepper flakes are another option, but personally I haven’t had great success. This made a mess and didn’t consistently work for preventing digging. It did help prevent cats from eating certain plants they had an affinity for, though.

Flush salts

Brown edges occur on leaves as they age. Salts and fertilizers in the soil will increase this. One way to combat the issue is by using bottled, reverse osmosis water, or rain water. Some areas in Sacramento have such pure water that it is not needed.

If you have well water high in calcium carbonate or boron, then watering every time (every third time at least) with higher quality water will help prevent salt accumulation. Additionally, remember every time you water, do so until water flows out the bottom of the pot. This will leach salts and ensure the roots are getting adequate hydration.

Fungal gnat prevention

It can be disconcerting seeing tiny flies around your potted plants. Wet soils are the ideal environment for fungal gnats to breed. Besides allowing soil to dry out between watering, try placing about ½ to 3/4 inches of horticultural sand, found at most nurseries, on the soil surface.

This acts as a barrier for the adults trying to lay eggs in your soil. You will have to reapply sand after each watering. If you have flies though, this is a very worthwhile and effective organic practice.

Ask the Plant Lady

Q: My broccoli and cauliflower are being eaten. What can I do?

A: Look for green worms on the underside of the leaves. Cabbage loopers and cabbage white butterflies both lay their eggs on many winter crops. The larvae feast on the leaves.

Hand pick the green worms or use BT (Bacillus thuringiensis), a bacteria safe to use on edibles. The larvae ingest BT, but cannot digest it and die. Reapply every five to seven days (check your product label). BT is found in most nurseries under various trade names.

Marlene can be reached my emailing: marlenetheplantlady@gmail.com Follow her on Instagram@marlenetheplantlady and flowerpowergardenhour.libsyn.com.