Q&A - Houseplants

Q. We have managed to grow an avocado tree from a seed that we never thought would shoot. It is about 25cm tall now & looking very healthy but we have no idea what to expect or do next. Any info would be great.

A. Avocado are fun to grow and can usually be kept indoors for about 3 years before they get too big. Keep the plant cool during the winter and repot in the spring when you can pinch out the tip to make it grow bushy. Keep the compost only slightly moist in winter but increase watering in the spring. Keep in a light spot but not in direct mid-day sun. Feed during the spring and summer with a houseplant fertiliser.

Q. I have recently started growing a banana plant (Musa Basjoo) and it has started to grow offshoots. Should I detach them and if so how?

A. If you want to grow new plants from the offshoots you should cut these off with some root in about April and pot up individually in a pot just large enough. You should preferably use a John Innes No3 compost. Pot on as soon as the roots have filled round the pot.

Q. I have started growing my capsicum plant 6 months ago from seeds. It is growing & flowering very well but it just does not produce fruit; the petals of the flower will drop off along with the stem. I would really appreciate it if you could advice me on what's wrong with my plant? I have tried giving fertilisers or abstaining from it, it didn't work.

A. It sounds like the flowers are not being pollinated and therefore no fruit can form. To assist the transfer of pollen you should spray the flowers daily with a fine mist of water. Once fruits have set feed every 10 days with a dilute liquid houseplant food until they start to colour. Keep the compost moist at all times and give the plants some direct sunlight.

Q. I was given a clivia plant 4 years ago which is quite pot bound with 5 plants. It has only flowered twice the first year when I had 5 flowers and last year with 2 flower heads (I was given the plant because it never flowered and they were fed up with it). I am unsure when and if it should be fed and how to encourage it to flower. It is in a large cool light filled room that faces north and only watered when I think about it.

A. Clivia need a temperature of about 16 degrees Celsius. They should be kept warm and watered but not too wet in the summer. From autumn to spring only water if the compost dries out completely. In winter keep the plant in a cool room and allow it to rest. Do not move the pot when in bud or flower and do not feed. Avoid direct sun in summer but keep in a bright spot all year round. Only pot on when the plants are completely pot bound. Do this in the spring without dividing up the plant. Knock the plant out of the pot and wash the old compost away taking care not to damage the fleshy roots. Repot into a slightly larger pot using a soil based potting compost such as John Innes
No1.

Q. I have received a coconut palm in a pot. Please could you tell me how to care for it.

A. To keep your palm healthy you should maintain a minimum temperature of 10 degrees Celsius (50 F) in winter and place in a position out of direct sunlight. The compost needs to be well drained but slightly moist and the leaves sprayed with a fine mist of water daily if possible in heated rooms.

Q. What are the best conditions for growing Gardenias?

A. Gardenia are unfortunately not the easiest of houseplants to grow well. For flower buds to form a night temperature of 16-18 degrees Celsius (61-65 F) is required and during the day should be about 6 degrees higher. An even temperature and careful watering are required to prevent bud drop. A minimum winter temperature is 16 degrees centigrade. Bright light is essential but avoid direct mid day sun in summer. Keep compost moist at all times, reducing watering in winter. Use soft tepid water. Mist leaves frequently. Repot in spring every 2-3 years. Feed in spring and summer with a houseplant food.

Q. We have a papyrus plant and the tips of the leaves are brown. The person who looks after them has the pot swimming in water which I can't imagine is good but she insists that is how they live. Thank you.

A. Papyrus grows naturally on river banks, so thrive only if their roots are in water. The brown tips to the leaves may be due to drying out at some point. You can remove any unsightly leaves and repot if the plant roots are too constricted.

Q. Repeatedly I try to grow Spathyphyllum but before long the flowers become tiny or green - or both. I have grown them for years but have only had this problem in the past couple of years. What am I doing wrong?

A. The flowers tend to turn green as they age but should start white each year. You may need to repot your plants and give them a regular feed with a houseplant food. Also make sure you grow them in semi-shade in summer and bright light in winter.

Q. I have a Stephanotis which has lots of leaves but NO flowers, help please.

A. Stephanotis are not easy plants to grow. They need an average temperature of 55-60 degrees Farenheight (12-15 degrees Celsius) in winter and a brightly lit spot away from direct sunlight in summer. Try not to feed more than once a week and see if flowers appear.

Q. I recently purchased a Streptocarpus Crystal Ice. The instructions advise feeding in the winter with a high potash feed. I have searched the local garden centre but cannot find a houseplant feed containing potash. Can you advise please.

A. Your plant will not flower as profusely in the winter due to the lower light levels and should only be watered occasionally as necessary. Feeding with a normal houseplant food such as Baby Bio, Phostrogen or MiracleGro once or twice a month should be sufficient. These feeds contain a balance of the nutrients needed to maintain health and flowering. However if your plant is not flowering you can try feeding occasionally with a tomato feed such as Tomorite that contains higher levels of potash, which is more normally referred to on packaging as Potassium (chemical symbol K).

Q. I have got a Swiss Cheese plant that has grown quite large, the leaves are about 2 foot wide, and there seems to be a flower growing. I cannot find any photos or information on this. I know that it does fruit, but that is about all, can you help?

A. The Swiss Cheese plant is called Monsteria deliciosa. The flowers and fruits, which are edible generally, appear only on conservatory plants where the temperatures and light levels are higher. They don't like direct sunlight and prefer a temperature of 10-17 degrees Celsius (50-65 degrees Farenheight). The compost should be watered well in summer but allowed to dry out between each watering but in winter it should be kept just moist.