Gardening with Gary

Gardening Advice from an Expert

Passion Flowers

Q. I have recently purchased a passion flower vine ready to flower. I am in zone 4, we are averaging 50-60 at night and 70-80 daytime. Is it OK to put this plant outside? I am aware that I will have to bring it in, in the fall.

A. Yes, this plant [Passiflora] is not tolerant of cold, as you know. But they do well outdoors for the late spring and summer and then return to the confines of the house for the long winter.

50 F is the minimum I would like to see you subject the plant to. If you could please take the plant outdoors after the sun warms the day, let acclimate to the weather and then bring back into the house before temps fall again. Do this for a week and the plant will become hardened, as we say.

Once the low temps are above 50 F, you may leave the plant outdoors in a very sunny location, as long as you watch the watering and keep the soil evenly moist but not soggy. Supply a trellis for climbing and the foliage will receive more light and induce more flowers all summer long. They are a sight to behold when in full bloom, with colors ranging from purple-red to lavender to deep rose to pink.

Q. I have a passion flower. Is it best to nip the top out? It is over 7 feet tall, which I have grown from seed this year. It is just starting to shot from the main stem.

A. All vines need a little help from time to time. I wish you had pinched out the top growing tip when the vine was about two feet tall. By now, you would have many branches going various directions. This increases the spreading of foliage for light and air, and thus produces more flowers!

So, cut off at least one inch of the growing points wherever they are. That will ensure that the growth cannot continue in a straight line anymore. You will get 2-6 branches coming out below the cut from viable buds all along the main stem. Train each of them with string carefully to stretch over a wall, trellis or mesh screen. It will soon be very beautiful.

Congrats for starting your large plant from a little seed. Good for you!

Help~ I need information about passion flower plant.

A. This is a wonderful group of plants which are grown worldwide. With a little guidance, you will soon be growing some real beauties.

Put your plants close to a wall or fence if possible, in beds that are south facing, dry, and well-drained. Add sharp sand if necessary to improve drainage and help plants establish roots. All Passiflora hate having wet cold roots. Train them up a diamond shaped wooden trellis or similar. Generally all Passiflora love sun.

Very large plants may need little feeding if they have a large root system and are in fertile soil. Smaller ones will benefit from a high potassium fertilizer such as MirAcid or Peters 5-50-5. Organic alternatives include Maxicrop Organic Seaweed Extract, banana skins or comfrey. Too much nitrogen gives good leaf growth but few flowers. A stressed plant will flower better than one that is too comfortable.

Water daily when newly planted in the ground. Once established, water heavily only once a week to encourage roots to go deep, which will increase winter survival chances. Check pot plants every day in summer. If in doubt keep them slightly dry.

Young ones always find their first winter hard. Some plants can regrow from the roots. The more vulnerable plants should be grown in 10" pots with a bamboo tripod and brought indoors at the beginning of winter and kept fairly dry, with the emphasis on both good light and air circulation, rather than on heating the air. Artificial lighting is very helpful. If you think you might lose a plant in a bed outside over winter, take cuttings in the summer to grow indoors over winter.

If getting too big, you can cut back in the middle of the growing season but never near the end, as the chances of winter survival will be reduced. It is best to leave the plant looking messy over winter and prune only after growth has restarted. Even then, never cut the whole plant hard back. Always leave some long straggly bits. When pruning, never cut hard to the main stems. Always leave a 3''- 4'' stub.

When they are happy and all their needs are being met, they rarely have pest and disease problems. When struggling though, especially over winter, they are particularly prone to mealy bug and spider mite. They can also suffer from mildew if insufficient water or air circulation.

Assistance from: Myles Irvine, Surrey, UK.

Here is their fine organization, for more info:

http://www.passiflora.org

Q. I live in Houston, Texas. When should I cut back the Passionflower Vine?

A. Passion flower, passion vine: Passiflora pfordtii
The great value of vines is in the masses of color and green cover they produce as a foil for blank walls or fences. The vines are well adapted to desert conditions. The seasonal color range covers the entire year. Some vines even double as ground cover for steep slopes, others have tendrils that cling to most any surface. Many rely on some type of support.

Keep in mind that you develop more compact growth with several prunings during the year. Their vigorous growth often requires severe pruning to keep within reasonable bounds. Reacts favorably to pruning in early summer. Requires full sun for good growth and flowering. Freezes back but recovers quickly in spring. Maintains a moderate growth rate with moderate supplemental watering. Direct growth with pruning, remove dead vegetation in spring. Grows best on wall or fence. Use as wind or sun screen in mini-oasis. Most are hardy to 32 degrees F.

Water requirements are generally in the low to moderate range, a few in the high range. Highly adaptable. Recover rapidly if frost damaged.

Ben writes~ I grew three passion flower plants from seed this year. They are outside now and the soil in the pots is covered by little flies. What are they? Are they dangerous to the plants?

A. They most likely are fungus gnats which feed off the top layer of soil but do lay their eggs in this layer which turn into larvae but do little damage to established plants [see below]. They are more an annoyance, inside and out. If the number increases greatly, consider a systemic insecticidal drench available at a garden center. Or use a pyrethrums spray or aerosols labeled for "gnats" or "flying insects." Repeat applications several times if necessary. Keep the plants on the dry side as that will kill of their food source. Remove old debris and decaying plant material from the spoil surface. Larvae or maggots, which feed in soil high in organic matter, can injure the roots of bedding plants, African violets, carnations, cyclamens, geraniums, poinsettias and foliage plants. Possible plant symptoms are sudden wilting, loss of vigor, poor growth, yellowing and foliage loss. Fungus gnats inhabit fungi or dead plant materials and are harmless to humans and animals.

Assistance from: http://ohioline.osu.edu