No flowers on Plants

Symptoms

The main sign is a lack of flowers on a houseplant that you expect to bloom. A second sign is a plant that stretches toward the light and produces few or no flowers. That stretching is linked to too little light, which makes the plant stretch instead of bloom. Start by noticing which of these two signs you see on your plant.

Hydrangeas can show the same lack of flowers after a winter freeze damages their flower buds and stems. Lush foliage with few flowers can also point to excess nitrogen fertilizer. In each case the problem is the same: flowers you expected do not appear.

Causes

Improper nighttime temperatures, either too low or too high, can keep a plant from flowering. Inadequate light, in duration, intensity or both, is another cause. Too little light can make the plant stretch instead of bloom.

Overwatering can lead to root rot. Underwatering can cause roots to die back in soil that stays too dry. Root rot from overwatering and root dieback from dry soil are two different root problems. Insufficient fertilizing leaves the plant without nutrients to spend on flowers. Excess nitrogen fertilizer produces lush foliage at the expense of flowers.

A pot that is too large can prevent the root-bound state a plant needs to bloom. Winter freeze damage can kill flower buds and stems on hydrangeas that bloom on old wood. Pruning old-wood hydrangeas between autumn and early spring removes next season's flower buds. A gift or florist hydrangea may not be winter hardy in your local climate.

The causes fall into a few groups: temperature and light, water and food, pot size, and hydrangea care.

Diagnosis

Start with the signs you can see on the plant. A plant that stretches toward the light and makes few or no flowers fits the cause of too little light. A plant with lush foliage but few flowers fits the cause of excess nitrogen fertilizer.

A pot that is too large can stop a plant from becoming root-bound enough to bloom. Overwatering leads to root rot, while underwatering lets roots die back in soil that stays too dry. Both are root problems, and they come from opposite watering habits.

Inadequate light can be a problem of duration, intensity or both. Nighttime temperatures that are too low or too high are a separate cause.

If the plant is a hydrangea, the causes change. Winter freeze damage can kill flower buds and stems on hydrangeas that bloom on old wood. Pruning those hydrangeas between autumn and early spring removes next season's flower buds. A gift or florist hydrangea may not be winter hardy in your local climate. In every case the symptom is the same: flowers you expected do not appear.

Treatments

Treatment starts with care, because the causes above are conditions of care and climate. Every treatment listed here is a cultural one.

Give the plant bright, indirect light, ideally from an east-facing window with a sheer curtain to block the sun's harshest rays. Also make sure it gets about eight hours of darkness every night. This light advice covers both brightness and the length of the night.

Keep the soil evenly moist, feeling like a well-wrung-out sponge, rather than soggy or bone dry. The moisture advice avoids both soggy soil and bone-dry soil. Fertilize on a regular basis, and choose a fertilizer that does not use urea as the nitrogen source. Follow the label directions rather than applying more than recommended. A regular feeding routine addresses insufficient fertilizing, and following the label guards against excess nitrogen.

Repot into a pot no larger than about one-third the diameter of the plant, so it stays root-bound enough to bloom well. These steps match the causes of too little light, uneven watering, poor feeding and a pot that is too large.

For hydrangeas, choose a newer big-leaf variety that blooms on both old and new wood. The Endless Summer and Let's Dance re-blooming collections are examples. If your hydrangea is a non-hardy gift plant, plant a winter-hardy native hydrangea instead. Examples are Hydrangea arborescens 'Hills of Snow' and 'Annabelle'.

Prevention

Prevention comes down to keeping the conditions right before the plant misses a season of flowers. Provide bright, indirect light and about eight hours of darkness every night. Keep nighttime temperatures from running too low or too high.

Keep the soil evenly moist rather than soggy or bone dry. Feed on a regular basis, and follow label directions rather than applying more than recommended. Choose a fertilizer that does not use urea as its nitrogen source. Match the pot to the plant, no larger than about one-third the diameter of the plant.

With hydrangeas, avoid pruning old-wood types between autumn and early spring. Grow a variety that suits your climate, such as a newer re-blooming big-leaf type or a winter-hardy native. A gift or florist hydrangea that is not winter hardy in your climate is a risk to watch.

Plants most often affected

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