Fast-forward to today, and we have pushed the purchasing season back to Mother’s Day weekend. People are planting much earlier than before.
This past week is a good example of why we waited until Memorial Day. This weather has slowed plant growth considerably. I have tiny impatiens and vinca in flats and refused to grow this past week.
Soil temperatures have cooled, which also slows root growth. Cool soils and moisture are perfect conditions for diseases to occur.
The soil temperatures at two inches deep, the week of May 15, were around 72F. The soil temperature at the same depth on May 20 was 67.7F. At four inches deep, it was 68.2 on May 15, and on May 20, it was 63.
The only plants loving this weather are the cole crops. This includes lettuce, spinach, broccoli, kale, and others. Flowers such as snapdragons and pansies also love the cold weather. This past week extended their life a bit.
If plants can make it through this cool weather without diseases cropping up, they will take off once the temperatures warm up. Cross our fingers.
If you purchased or planted containers and hanging baskets this past week, particularly if the plants are growing in a soilless mix, be sure to fertilize. They need additional nutrients during the growing season to keep them beautiful.
Plants grown in a soilless mix require additional fertilizer because there are no soil particles (clay) to hold onto the nutrients. Frequent watering leaches the nutrients out of the container.
When grown in the greenhouse, they are fertilized regularly. Many times, plants in the greenhouse are fertigated or fertilized when irrigated.
We get them home and forget about the nutrients needed for growth, and they start to decline. Purchase an all-purpose fertilizer that is good for flowering plants and follow the label instructions.
We have large containers in Snyder Park Gardens & Arboretum filled with annuals. We add a slow-release, 90-day fertilizer at planting. This allows for small amounts of nutrients to be released over a 90-day period.
Then, every two or three weeks after they are planted, we use a liquid fertilizer to give them a boost. However, when they look pretty good and we are pleased with the size, color, etc., we cut back to once a month with the liquid.
Keep your containers and baskets looking great throughout the season with fertilizer. Once the nutrients are drained from the soil, they won’t have much to grow on.
Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at bennett.27@osu.edu.
About the Author