Primroses are wilting in my balcony pot?

The plants Need more water

Here is temperature range and growing conditions that most primroses do well in:

Light

Most Primula species thrive best in partial shade, but a few do just as well in full sun. Outdoors, most primroses prefer lightly shaded areas, with dappled and indirect sunlight. Avoid too much light since it may cause leaf burn.

However, in the case of indoor primrose plants, bright light is ideal for thriving. Place potted primroses in a well-lit area indoors with a good amount of sunlight throughout the day. This is important since insufficient light may affect the plant’s flowering ability.

Soil

Primroses grow best in fertile and well-draining soil. The ideal soil pH should be slightly acidic to slightly alkaline (2). You can also amend the soil with organic matter to improve its quality and condition.

Water

Watering primroses shouldn’t be tricky. They enjoy moist soil like most plants, especially since they can be susceptible to drought. Deep watering your primrose plants regularly, ideally once a week, will make them vigorous. However, avoid overwatering since excessive moisture in the soil often leads to root rot, which is not good for them (2). Water the plants before the top surface of the soil dry out completely.

Temperature

Growing primrose flowers indoors requires a range of about 50 °F at night to 70 °F during day time (2). You can grow potted primroses indoors, provided that the night temperatures fall between 50 and 60 °F. Generally, these plants do not tolerate extreme temperatures, particularly during the growing period.

Fertilizing

Primroses grown indoors do not necessarily need fertilization (2). Still, like other garden plants, these blooms appreciate light applications of fertilizers during their growing period.

Apply a balanced, water-soluble fertilizer at half of the recommended rate every two to four weeks. Stop feeding the plants after flowering.

ref:https://florgeous.com/primrose/

Give them some water.

Hi MJ, Primroses prefer cool conditions so I don't think the cold is a problem, especially since the one is doing really well in the same conditions. Try spacing the two that are wilting out a little. They like proper air circulation. Can you see any little grubs in the soil? One of the biggest problems with sudden wilting is weevils that eat the roots. They may also be infected with botrytis or yellow asters. In that case, you'll need to throw them away. Hope they come right, they're so pretty.

Most common reasons for wilting in primroses:

Bacterial Soft Rot

1. Primroses growing in warm, humid conditions or excessively wet soil may develop bacterial soft rot. This infection, caused by Erwinia carotovora bacteria, occurs most frequently at temperatures above 76 degrees Fahrenheit. Affected primroses typically decay and become dark green close to the ground before wilting completely. Preventive measures include spacing the plants for good air circulation, watering them from beneath and protecting them against wounds that invite infection. Control existing bacterial rot by removing and destroying diseased plants as soon as symptoms appear.

Fungal Root Rots

1. Three fungi -- Phytophthora, Pythium and Rhizoctonia -- leave primroses wilted and stunted with yellow, dying foliage. These soil-borne diseases target roots, limiting their ability to transport water and nutrients. Pythium wilts and kills primrose seedlings, while Phytophthora and Rhizoctonia attack older plants. Primroses in poorly drained or excessively wet soils are most likely to develop root rot infection. Avoid introducing root rot into your garden by selecting primroses with dense, healthy green foliage and well-developed roots. Discarding already-infected plants and irrigating only when necessary limit the diseases' spread.

Gray Mold

1. Although gray mold's (Botrytis cinerea) normal diet consists of dead plant tissue, moist weather with temperatures higher than 54 degrees Fahrenheit stimulates its growth on healthy plants. The disease discolors and wilts new shoots and leaves, usually covering them with fuzzy mats of gray or brown spores as they decay and drop. It disfigures flower petals with water-soaked spots. Dry conditions and temperatures below 54 F. halt its spread. To manage the disease, prune infected plant tissues, remove diseased soil debris and water the plants from beneath.

Viruses

1. Tomato spotted wilt, impatiens necrotic spot and primula (cucumber) mosaic viruses infect primroses through wounded tissue. Two sap-consuming insects -- aphids and thrips -- also transmit the tomato spotted wilt and primula mosaic viruses as they feed. Typical virus symptoms include wilting, deformed yellowing leaves, or flowers with spots, lines or mottling. These incurable disorders require the removal of affected primroses as well as nearby weeds that may harbor the viruses or their insect vectors.

Environmental Stresses

1. Just as primroses in overly wet soil s may wilt from root rot, those in dry soils and strong sun often wilt from lack of moisture. These plants need well-drained, consistently moist soil and filtered sunlight through the day. They decline when temperatures remain higher than 75 to 80 F.

My first thought is Primroses love water - don't underwater them.

Primrose love moisture!

Covering to protect them from the extreme cold should help them.

the soil seems very dry maybe just watering them will help

Mine will wilt with too much direct sunlight and Summer heat or from being too dry. These are very tough plants...trust me I have left them for dead being so badly wilted and with a good watering they come right back on their feet again! I always say you can't kill them!

Hi Mj, hope this helps you out, it could be a few things, but his will give you a way to check them all out, https://homeguides.sfgate.com/revive-wilted-streptocarpus-58779.html

too much water mixed with heat

Appear to be wilting from lack of water. What zone do you live in?