Plant Nutrition

Iron Deficiency

Tobacco Mosaic Virus (TMV) symptoms should not be confused with symptoms caused by iron deficiency. Iron deficiency symptoms generally show up as an interveinal chlorosis, normally starting at the shoot tips, but often they occur throughout the entire plant. Sometimes the leaves of iron deficient plants turn almost white. Symptoms of TMV show yellow and green mottling, upward leaf curling, leaf distortion and overall stunting. Bacopa, calibrachoa, scaevola, snapdragons, and petunia are crops susceptible to iron deficiency.

Fertilizing Garden Mums

Many growers will be potting up garden mums and it's a good time to revisit your fertilizer program. Mums are heavy feeders during the first few weeks. After flowers are formed, nutrient demand diminishes. Your fertilizer program and fertilizer selection should be based on irrigation water quality, so have your irrigation water tested if it hasn't been done and conduct regular soil tests to monitor soil fertility.

Update on Fertilizing Garden Mums

It is a good time to conduct a soil test and review your fertilizer program for your garden mums. Be sure adequate fertilizer is applied especially with recent rainy weather and if controlled release fertilizer is the only source of feed. Six to seven weeks after the cuttings were planted until the flowering plants are sold, feed levels can be reduced to 150 to 200 ppm twice weekly (depending on weather) until color, or even go bi-weekly with a Cal-Mag type feed. This will maintain foliage color without creating excess growth before flowering.

Forcing Hydrangeas

Allow newly arrived pre-finished plants to recover from shipping stress and to initiate active root growth (about 1-2 weeks) prior to transplanting into the final-sized pot. Hydrangea blooms are formed on the previous year's growth, so the flowers are already in place in the dormant buds. The ideal starting temperature for hydrangeas is a 60 to 62°F soil temperature supplied with bottom heat, while maintaining slightly cooler air temperatures (about 58°F). This allows root activity prior to bud opening on the shoots.


Monitor pH and nutrition on geranium crops. Using 20-10-20 constant feed for all crops could lead to low pH on geraniums resulting in iron/manganese toxicity symptoms. If the problem is not corrected early in the crop cycle, the crop will likely not recover in time for sales. This is a problem to prevent.

Changing Color of Mixed Fertilizer

Color changes in the mixing of Jack’s Professional fertilizers manufactured by J.R. Peters, Inc. has been observed by some growers.

It is not unusual for the color of Jack's fertilizer to range from a blue/green to a grey color when mixing due to the chelated iron in the formulation. Discoloration can also occur when the product is stored in high heat due to the plastic bags.


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