Plants in a townhouse courtyard and starting oak seeds

Question:

I read your column in the newspaper and have learned many things about gardening. However, I still have some unanswered questions and hope you can help me out before winter sets in. All of my plants are in containers because we live in a complex of townhouses and do not have any yard to speak of, but I just have to be able to grow some things.

I have an enclosed but uncovered patio. I have moved many of my plants into this area and I think they will be O.K. for the winter, but I have a 5 year old lemon tree that I am afraid will not make it without special care. The last two winters it has stayed at my son's house in front of a large south facing window. It has done fairly well, but it has gotten its seasons turned around and blooms in the fall and by spring the blooms fall off and that is the end until the fall again. I have put a lot of mulch over the roots, but worry that will not keep it from freezing. Do you have any advice for me?

I also have a 2 year old plumeria tree, which I have moved into the house, but my house does not lend itself to growing plants because of the window placements. Do you think a grow light would keep it alive and healthy?

Next I have rescued an acorn from our squirrel population and a passion flower seed pod and would like to plant them just to see if I could get them to grow. They will need to be in containers for at least the first year or so. Any instructions you could give me on these problems I would certainly appreciate.

Jan H.
Roswell, New Mexico

Answer:

Whether or not the lemon will survive in the courtyard depends on the nature of your courtyard. If the courtyard is an open-topped atrium surrounded by your home, the lemon tree may do well if it can get enough light. However, I suspect your courtyard is adjacent to your home and surrounded by walls. Without heated rooms around it, there may not be enough protection for the lemon tree. There may be a warm microclimate within the courtyard that will provide enough warmth for most of the winter if a portion receives direct sunlight that warms the walls and paving or soil. This will stay warmer than other areas. You can probably keep the lemon tree in that location much of the winter and bring it indoors during the coldest weather (especially when the cold winds are blowing).

The plumeria is even more frost tender and will need to be taken indoors more often. If containers for these plants are put on wheeled furniture dollies, you can fairly easily roll them indoors and out when needed. If the threshold of the door is too steep, you may need to make a temporary ramp to roll over. They can be kept outside most days and many of the nights. The grow lamp will probably not be sufficient for these plants for extended periods indoors. The cooler and brighter the room in which the plants are kept, the better. The plumeria will often drop its leaves and survive extended periods of time indoors.

The oak seeds may germinate well if they have not been infested with weevils. The thing you must determine is if they need a pretreatment to overcome dormancy or not. Oaks in the white oak group (Chinquapin, gambel, bur, and live oak) will germinate readily as soon as the seed mature if they do not dry out. Red oak seeds (Shumard and Texas red oak) must receive cool, moist pretreatment to overcome dormancy. It will not harm the white oak seeds if you pretreat them also, but they may sprout during the pretreatment period, so you must watch them carefully and be prepared to plant them as soon as they begin sprouting. Pretreat them by placing them in a resealable plastic bag with moist (not soggy) peat moss or vermiculite. Place this bag in the refrigerator (not freezer) for up to 90 days (watching for sprouting). After pretreatment, or when they begin sprouting, put them into large containers of potting soil (depth is important since they will form tap roots). Then you can treat them as you would other container plants, water as needed, fertilize occasionally, and enjoy them.

The passion flower seeds should be planted in good potting soil and kept warm and moist. If the seed are viable (alive) they should sprout fairly quickly. The passion flower vines become rather large, so give them pots large enough to support the growth.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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