I attended a plant talk a few months back and the person giving talk made a point of discussing how easy it is to grow Comfrey down here. She said you just toss out back and it grows, and you can cut the leaves up into pieces and each of the pieces will grow.
Well by the end of the talk we were all terrified of Comfrey. She sold out all the other plants she brought for sale, I don’t think a single Comfrey plant sold.
What have you planted that you regret? is a some what current thread over on the Garden Web Forums Texas section and it got me to thinking about that talk and what is invasive in Houston. Reading the garden thread it is clear one gardener’s behemoth is another gardener’s friend.
Down here there is no winter die back to pommel your mistakes.
General rules of thumb:
1) Anything growing wild near you will love your garden. Regular water, fertilizer and it’ll go to town on you.
2) Beware of gardener’s bearing gifts. If she has so much of it she is giving it away that should be a warning sign.
3) If it is really cheap to buy that is because it grows fast and it is easy to grow.
4 ) Vines should always be treated with suspicion.
Then of course there is invasive as in taking over your garden and invasive as in crowding out native species. I couldn’t find a comprehensive list of invasive species in Houston, only bits and pieces across several websites. Here are invasive plants I found listed on various sites:
Alligatorweed ( Alternanthera philoxeroides )
Balloon vine ( Cardiospermum halicacabum )
Brazilian peppertree ( Schinus terebinthifolius )
Broomrape ( Orobanche ramosa )
Camelthorn ( Alhagi camelorum )
Chinese Tallow Tree ( Triadica sebifera L. )
Dalmation Toadflax ( Linaria dalmatica L. )
Deeprooted sedge ( Cyerus entrerianus )
Distaff thistle ( Carthamus lanatus )
Downy Brome ( Bromus tectorum L. )
Eurasian watermilifoil ( Myriophyllum spicatum )
Giant duckweed ( Spirodela oligorrhiza )
Giant reed ( Arundo donax )
Hedge bindweed ( Calystegia sepium )
Hoary Cress ( Cardaria draba L. )
Hydrilla ( Hydrilla verticillata )
Japanese dodder ( Cuscuta japonica )
Japanese Honeysuckle ( Lonicera japonica Thunb. )
Johnsongrass ( Sorghum halepense L. )
Kudzu ( Pueraria montana Lour. Merr. )
Lagarosiphon ( Lagarosiphon major )
Multiflora rose ( Rosa multflora Thunb. )
Musk Thistle ( Carduus nutans L. )
Paperbark ( Melaleuca quinquenervia )
Privet ( Ligustrum spp. )
Purple loosestrife ( Lythrum salicaria )
Rooted waterhyacinth ( Eichhomia azurea )
Russian Knapweed ( Acroptilon repens ( L. ) DC )
Russian Olive ( Elaeagnus angustifolia L. )
Saltcedar ( Tamarix spp. )
Salvinia ( Salvinia spp. )
Serrated tussock ( Nassella trichotoma )
St. Johnswort ( Hypericum perforatum )
Scotch Thistle ( Onopordum acanthium L. )
Spotted Knapweed ( Centaurea biebersteinni DC )
Swingle Tree of Heaven ( Ailanthus altissima ( P. Mill. )
Saltcedar ( Tamarisk )
Torpedograss ( Panicum repens )
Tropical soda apple ( Solanum viarum )
Water spinach ( lpomoea aquatica )
Water hyacinth ( Eichhomia crassipes )
Water lettuce ( Pistia stratiotes )
Whitetop ( Cardaria spp. )
Yellow Star Thistle ( Centaurea solstitialis L. )
Yellow Toadflax ( Linaria vulgaris P. Mill. )
What to do when you find invasives in your garden or plant harmless looking plants that later decide to conquer the world? Yank them if you can, if not weed killer is your friend. Most weed killers kill by contact. So plants you wish to keep can be covered while you perform chemical warfare on the trouble makers.
Galveston Bay Invasive Plant Field Guide
Invasive Plants of Southern Forests
Weeds gone wild
Center for Plant Conservation – Invasive Species
Lady Bird Johnson Wildflower Center Invasive Plants
Invasive Aquatic Plants in Texas
Texas laws on invasive species
Global Invasive Species Database
Invasive Species: Plants