the show

Aquaponics and Rain Water Catchment

air date: June 22, 2013

Keep that rainfall on your garden with tips from Sunflower Design ecological designer Adams Kirkpatrick. On tour, find out what aquaponics is all about with Rob Nash in his Austin Aquaponics greenhouse.  Daphne explains why squash flowers and fruit fall off your plants and how to pollinate to ensure success. Her pick of the week is summertime blooming shrub, Duranta. Trisha fends off root knot nematodes that destroy plant roots.

Episode Segments

On Tour

Rob Nash Austin Aquaponics

What’s aquaponics all about? Find out as Rob Nash takes us on a tour of his Austin Aquaponics greenhouse where aquaculture and hydroponics unite for water conserving crops. On his rocky land that could never support food, he supplies local harvests all year to restaurants, drop-by customers, and the Lone Star Farmers’ Market from aquaponics media-based and raft beds, along with wicking beds.


Watch more "On Tour" videos on YouTube →

Question of the Week

Why do cucumber and squash flowers and fruit fall off the plant?

This question comes from Central Texas Gardener’s Facebook page but lots of gardeners are asking about this.

I love this question, since it involves so much of the easy science behind the life cycles of flowering plants.  Some plants have very little trouble with pollination, while others struggle.  Plants in the Cucurbitacea, the squash family, can have a challenging time with pollination, especially with our native bee population in decline.

Squash, cucumbers, and others in this family (sometimes called pepos by gardeners) have a long, full fruit with lots of seeds.  Well, in order for that fruit to develop at all, and then to expand and elongate, pollination must occur.

If there’s no pollination, the plant has no reason to make a fruit.  A fruit without offspring would be a serious waste of resources, and Cucurbits simply don’t waste their time.

If a little bit of pollination occurs, then a few seeds will develop and the fruit will expand, but will be very small.  It’s all part of nature and the conservation of precious resources for survival.

Unfortunately, lack of pollination in squash and cucumbers is very common, but the good news is, the problem is easily solved:  you can pollinate the flowers yourself.  Many gardeners tell me that they simply use their forefinger to grab a little pollen from the male flower to pollinate the female.

Fancier folks might use a paint brush to do the same job, especially if they’re doing controlled cross-hybridization between species and want to ensure against contamination.  You can also simply remove one flower and use it to pollinate the others.

Plants in the squash family have two types of flowers: male and female.  The male will have an elongated stamen which contains the pollen.  The female flowers produce the fruit, which you can see as a tiny swollen area behind the tubular flower.  Dab pollen from the male stamen into the center of the female flower—onto the stigma—which is the elongated part in the center of the flower. All of the seeds in the flower need to be pollinated, or the fruit will be small and underdeveloped.

Bees can do the job for you, but if you don’t have a good bee population, you’ll have to assist. Many gardeners like to keep row cover over their young plants to fend off the dreaded squash vine borer moth. But once the flowers bloom, you’ll need to remove the cover for bee pollination or do it yourself.

Encourage bees with flowering plants in the vegetable garden or nearby.

Watch Trisha’s video on tackling squash vine borers.

Watch more Question of the Week videos on YouTube →

Plant of the Week



This rapidly growing shrub can get 10 to 15 feet tall and over 5 feet wide. It's listed as hardy to only zone 9, so here in Central Texas, it dies to the ground in winter in most gardens. But in our demonstration garden at the Extension office, Duranta is evergreen, hardly even skipping a bit in the coldest of winters. We have it planted against a wall, with full sun exposure all day, so the heat that builds up during the day is radiated during the night, keeping the microclimate much warmer there than in other areas of the garden. If Duranta dies to the ground in winter in your garden, simply prune it back to about 3 inches from the ground and it will reemerge from the roots in spring. There are several cultivars of Duranta, but my favorite is the purple-flowering one. It flowers from early spring all the way through fall and doesn't bat an eyelash at heat or the lack of rainfall. We also have a white flowering cultivar in our garden, and it's also very pretty, and forms more pretty yellow, ball-like fruits than other cultivars. If you want to attract native birds to your landscape, they'll love the fruit of the white-flowering cultivar. Duranta will perform best in full sun, but can take light shade. To do in your garden this week, it's time to dead-head all of those spent blooms on your flowering plants, to encourage a second flush of color for the summer. If you have blackberries and have harvested all of the fruit, tip-prune the canes back to about 4 feet to promote branching, and thus a heavier fruit crop next season.