Hey there all:
I searched forever before finding this site, and am loving the fact that it has so much information!
I've been living in Houston for about 15 years now, but only recently bought a house. As of July, we will be moved in and the first thing I want to do is to start getting ready for as much food growing as I can. There's a HUGE backyard that I want to plant with anything that can provide food. To that end, I am probably going to bug the living daylights out of all of you, over and over and... well, you get the picture.
Before Houston, I lived in Maine, and worked a garden there. There was a metric ton of stuff that we had to do because of short growing seasons and such, which is why I got interested in making efficient, sustainable, gardens. Houston, however, has a VERY different climate and growing season. And to that end, I'm trying to learn everything I can lay hands on to make my back yard a good vegetable and fruit producer.
This is, therefore an intro, and a bit of a warning that I am an information junkie and will be asking a ton of questions. In the meantime: HI! Pleasedtameechya'll.
New to Houston Gardening - Looking to Learn
What you will find is that we have a lot more in common with Maine than you might have originally anticipated!!
Except for Okra, Southern Peas (Cowpeas, Black-eyed Peas), Chile Peppers, and the like, Houston really has two short gardening seasons, rather than one long season. July and August have sustained temperatures of 85-100 and humidity of 75%+ which put most vegetable plants into a very stressed, unproductive state that they tend not to recover from. They are unable to fight disease or insects particularly well, and tomatoes typically will not set fruit in those conditions at all.
March 9th is my outside planting date for tomatoes if the more reliable weather websites (never trust the dude on TV) like NOAA or Weather Underground ( http://www.wunderground.com/ ) are reporting clear sailing (no temps < 40). If you are inside loop 610 you can plant some years as early as February 21st. Then I check the weather websites almost every day and pray for no frosts. I've got blankets and tarps ready if a frost is expected. Unfortunately, if you wait for all danger of frost to pass and plant in April, you will get very few tomatoes.
It is depressing to see people buying tomato plants in late April or even May since I know they will get almost nothing for all their hard work. We have to get our plants in as early as possible. The soil temperature is ready and the plants start growing immediately, but there's just that darn risk of frost.
Most of my tomatoes set their fruit in April and early May, most of my harvest happens in late May, through June, and then if I managed to keep my plants alive with all the fungal problems we get here, I still rip the plants out in mid-July. So that's a 4 month growing season right there, at least for tomatoes.
I do start some seeds for cherry tomatoes and maybe 1-2 medium fruited tomato plants on June 15th to plant out July 31st and have a few tomatoes in September and October but they won't set substantial fruit until overnight temps drop below 70 and then when we start getting overnight temps in the 40's, that sucks the flavor right out of the tomatoes on the vine (why you should never refrigerate tomatoes!).
I don't want to discourage you. I started gardening 3 years ago and knew almost nothing. :) I've grown for 5 seasons if you include the fall crops. The first year I wandered into Home Depot and bought a bunch of Celebrity and Roma tomato plants and stuck em in the ground and they produced well but I was not impressed with the flavor. Then I discovered heirlooms and some of the better hybrids and had a pretty good season last spring. This year is turning out to be an amazing year so far (~400 tomatoes on 32 plants, and some of those are fussier varieties) as we have had very little rainfall (this is a good thing!) and lots of cool nights in the 50's and low 60's which are crucial for good tomato fruitset.
For the 10 years I have lived in Houston, we have had at least one span of 3-5 days of torrential, monsoon-like rains in a row which are really tough on vegetable plants. They were not designed to utilize 15-20 inches of rain in 72 hours!! We plant in raised beds -- the Houston soil is typically heavy, sticky, yucky clay called "gumbo". But even filling them with loose, well-amended soil and applying a thick layer of straw or other mulch, that is just too much rain!
I have posted a bunch of comments about growing Tomatoes about halfway down in this thread which you might want to read:
http://davesgarden.com/community/forums/t/802919/
If your life is about more than tomatoes, then let's look at the bright side!!
Beets, Carrots, Brussels Sprouts, Cauliflower, Broccoli, Swiss Chard, Lettuce, etc. get planted in October and November and harvested in the early spring. Beans and Cucumbers are planted in August and harvest through to November (I had a mountain of fresh green beans and fresh pickles for Thanksgiving dinner). Snow peas do particularly well here if planted at the right time. I've also had success with potatoes, once you get used to the idea of planting them on January 15th!!
We have plenty of time to grow melons here that you might not have been able to grow in Maine. And then there's the citrus! Oranges, Grapefruits, Tangerines, Lemons are a staple in any fruit-fanatics Gulf Coast property. They have dwarf varieties of all of these now, so you can have a large productive shrub rather than a 30 ft tall tree. Some people even grow Avocados here!
Bell peppers don't do that well here, but Italian frying peppers have the same flavor, texture, and uses and are just a little smaller. Carmen, Golden Marconi, and Jimmy Nardello are fantastic and fantastically productive.
One book I recommend is Dr. Bob Randall's Year Round Vegetables, Fruits and Flowers for Metro Houston. It's locally published and not always easy to find. RCW Nursery has it. Wabash Antiques (a great garden shop and nursery) and Buchanan's Nursery have it.
The gardening calendar in the book is a little tough to read because it's non-graphical and split over multiple pages. I spent a day turning it into a graphic which you can view here:
http://www.feldoncentral.com/garden/HoustonGardeningCalendarBobRandall2.png
You said you are interested in Sustainable Gardening. You will probably be interested in the courses offered by UrbanHarvest, an organization in Houston which has classes and courses in all aspects of organic and sustainable gardening. They offer an intensive permaculture course as well. I'm just a member of UrbanHarvest, and I am not fully organic (sorry!). But they are a good organization so I mention them when I can. http://www.urbanharvest.org/
By the way, I hope you will make it to our 2nd annual South East Texas Tomato Fest ( http://www.settfest.com/ ), an open-to-the-public tomato gathering and tasting. It is organized by me and other members of Dave's Garden. You don't need to bring tomatoes since this is your first year. :) :) We should have 90 tomato varieties cut up and ready to taste. You are also welcome to save a few seeds if there is a variety you particularly like!
This message was edited May 13, 2008 11:03 AM
Welcome to the forum! I'm a native Houstonian of many, many years and a gardener of a lot of those years including trees, shrubs, vines, grass, annuals and perennials plus fruits and veggies. and I STILL have questions. People here on the TX forum are so helpful and have so much experience and many are quite learned on many aspects of Houston (and TX) gardening. They are also very patient in answering questions - even going step by step by step. You won't find a better bunch of people! If you have a question as to where to find something in DG just ask and they can tell you "where to go". HeHe. Manys the time I had a senior moment and couldn't find where, the recipes were, and all I had to do is ask and was pointed in the right direction. Questions are never stupid - answers sometimes are so don't hesitate to re-ask a question if you don't understand. Happy veggie gardening!
Ann
Feldon30: Wow! You are a font of information. Thank you.
I actually am a regular purchaser at the Urban Harvest Farmer's Market, and yes, when I had the chance I definitely bought the Metro Houston book. I've only just started reading it in my "copious free time" (riiiiight - new house contractor worries anyone?), and can see that it really is a wealth of good information. However, I've only JUST started, so it will be a while before I get anywhere close to your knowledge.
There is more to life than tomatoes - although plenty of tomatoes makes lots of good Italian sauce, so you have to have some good ones. I'm definitely going to have to check out the Tomato Fest.
PlantLadyHou: Thank you. One of the things I've noticed all over the boards and site is exactly what you say: A group of very friendly, sweet and enthusiastic people that really are passionate about gardening.
I don't have any veggie advice, but welcome to Dave's Garden and the Texas forum! ^_^
I've been growing vegetables mixed in with everything else for 18 years here--welcome to the forum.
Take those planting dates with a grain of salt--esp. the ones in that book, really depends on the weather in any particular year. Also depends on where you live in Houston.
I'm in far west Houston, definitely not in what's referred to as the the "Banana Belt" of Houston (south of I10--but I do grow some cavendish miniature bananas); I am north of I10--my spring tomatoes are always in the ground by March 1st. Peppers like it warmer, 3rd week of March, fall tomatoes mid to late July. Everything else depends on the year. Spring lettuce I never do after Jan 30--I never do spring broccoli or brussell sprouts; it gets too hot too fast. Fall is really the best season and over the winter for the greatest variety of what you can grow.
Like I always say--shade is very under-rated in Texas in the summer and full sun in winter here is like up North in April-May; its a latitude thing....
Debbie
I am new to gardening in Houston too. The first year I was busy having a baby, but I did manage to stick a few tomato plants and peppers in the ground. I planted the tomatoes too late I guess for a lot of summer tomatoes, but I got a bumper fall crop (morning sun, afternoon shade and they didn't die in the summer.) I picked the green ones before the last frost and had tomatoes at Christmas. The pepper plants survived the winter with a little mulch and have already given me a few peppers.
I have learned that it isn’t enough to set seedlings outside on warm days and on the windowsill on cold days. Next year I will buy florescent lights. The 2 inch peppers on the bottom left are the ones I grew. The ones on the top left are the ones I had to buy from the store.
I also decided that the next time I make a raised bed, I will use the Lasagna method or use a mix with peat moss. This year I used only $1 bags of composted manure from Lowe’s and my plants look sick. The squash leaves have yellow around the outside. The zucchini has milky spots, and one of the peppers is starting to turn yellow and brown.
My learning curve has improved dramatically since joining Dave’s garden. I dream of one day collecting my own open pollinated seeds and eating the tastiest of vegetables.
I have rust and fire ant problems, but that is a whole different story.
Tabitha
Welcome Hastur and Madrid2000. You'll love this site and all the folks in Texas.
I grow veggies, herbs, flowers, shrubs, fruit trees and anything else I can get my hands on. I have about 9 tomato plants that do very well but I'm certainly not a tomato expert. Just grow enough to eat and share. I have eight 6' X 6' raised beds in the back for the vegetables and herbs. The rest of my yard is mainly planted for butterfly and hummingbird gardening.
Tabitha, have you been watering in the late afternoon or in the evening? That can cause the problems you are having. Your bed looks great. Are you feeding the veggies anything?
Maybe that is part of the problem, I teach first graders during the day and run after a 15 month old in the morning and evenings. My plants get watered when it rains, or about once a week on the weekend. Twice a week in the evening if they're lucky or just transplanted. I thought that watering in the morning when the leaves were wet would spread diseases. Why is the evening better? It would be great if I just had to water differently to make them look better! I added some kind of composted grass or pine straw (can't tell which) to the top. I also bought molasses, apple cider, and seaweed stuff to try and make Garrett juice as recommended by "the dirt doctor" Howard Garrett. I was hopeing that I could use the organic stuff that has been sitting neglected in the back corner of the yard for a year to make compost tea. It isn't black crumbly stuff yet, but it is falling to pieces. I am trying to go totally organinc because my daughter likes to taste the dirt. She often has brown lipstick when she helps me in the garden. LOL Let me know if you have any other tips to make my plants healthier.
Tabitha
Originally posted by madrid2000:
I also decided that the next time I make a raised bed, I will use the Lasagna method or use a mix with peat moss. This year I used only $1 bags of composted manure from Lowe’s and my plants look sick. The squash leaves have yellow around the outside. The zucchini has milky spots, and one of the peppers is starting to turn yellow and brown.
The $1 bags of soil at Lowe's, Home Depot, and Wal-Mart, whether they are labeled composted manure, humus, topsoil, or potting soil are actually all about 90% sand. If you look on the package, it says "contains no less than 10% manure". I strongly advise against using them.
Black Kow composted cow manure is $4.62 a bag because it is the real deal. It is silky smooth, incredible stuff so a little goes a long way. In a 3 x 12 bed, you could get away with as few as 3 bags of Black Kow and the rest filler of peat moss, shredded pine bark (great as a filler and for loosening up the soil -- avoid any of the 'super black' or 'super red' or 'treated to prevent fading' mulches).
Also if you are adding straight peat moss like those bales of Premier, note that it does not contain a wetting agent so it will repel water and refuse to moisten like potting mix does. The answer is to add a teaspoon of dish/hand soap (preferably a straightforward one like Palmolive without antibacterial, or one of the natural/green products) to 1 gallon of water and water the peat moss well. The soap will encourage the peat moss to accept and hold water as you are expecting it to.
Originally posted by madrid2000:
My plants get watered when it rains, or about once a week on the weekend. Twice a week in the evening if they're lucky or just transplanted. I thought that watering in the morning when the leaves were wet would spread diseases. Why is the evening better? It would be great if I just had to water differently to make them look better!
My goal when I am watering tomato, pepper, cucumber, etc. plants is to not get the leaves wet at all. I use soaker hoses to water the soil and hopefully get little or no water on the foliage. The reason why it is recommended to water in the morning, even if the plants have some dew on the leaves, is that the heat of the day and bright sun will usually quickly dry off the leaves. If you water in the evening, then the plants are "going to bed wet" and those wet leaves will be an open door to fungal and bacterial diseases all night long.
Gardening completely organic in Houston is a challenge. It is your choice if you want to use a fungal preventative, either an organic one like Serenade, or a chemical like Daconil (chlorothalonil). I have compared the MSDS and papers on both and they are surprisingly similar as far as side effects, etc.
Gardening organic in Houston is much easier than gardening non-organic anywhere
=)
dmj,
Curious what do you use to deal with stink bugs?
I don't have a big problem with them because I scatter my tomatoes around the property. I don't have any 2 plants next to each other. I also don't use earth boxes or containers for tomatoes.
I am, however a commercial bulb grower in a coop--two of my 5 partners do vegetables, certified organic by the state of Texas--my 2 growing fields are on their property in Bellville and Magnolia (not very different from Houston, the Bellville location is less than 15 miles from me). They don't have a big problem either--but again, no monoculture there either. Tomatoes are such a fast crop in spring that by the time the problems really set in, the season is over anyway. They will sometimes use insecticidal soap--one of them doesn't have a lot of time (we also own 2 other non-agricultural businesses as a group) so I sometimes do that for him.
This is one tomato plant--that's a 10' wide bed of LA Iris from the brick path to that short 3' fence on the left. Its sprawled all over the LA Iris (going dormant for the summer), my daughter's patch of "funeral parlor glads" (another story there), and behind it, its sprawled against a Hibiscus coccinea for added support (not intentionally). See a problem? I don't, and it will be gone by about the first of July.
and if you turn from that location and look east, you'll see this lovely Crinum 'Peach Blow'.
My point is mix your vegetables in with your other plants, much fewer problems, it confuses the bad guys.
The plant police will not come tell you that you can't grow cucumbers right next to Gladiolus oppositiflorus var salmoneus, Bessera elegans, and daylillies. Or they would have come taken me away long ago....
Debbie
I am on 1/5 of an acre (including a large house and swimming pool) and am growing 37 tomato plants, 18 pepper plants, 21 sq ft of bush beans, squash, cantaloupes, blackberries, cucumbers, 24 sq ft of pole beans, etc. So I have to make the most use of my space. I currently have 6 garden beds, two 4' x 8', two 4' x 16', and two 3' x 16'. I have my tomatoes in 3 of the beds (and some in containers) and use 12 Texas tomato cages along with 25 cages that I made out of galvanized fencing. The Texas cages secure the other cages together.
Due to surrounding trees and the angle of the sun (my back yard faces North), I have to place things such that the tomatoes won't shadow anything else. Mixing and matching tomatoes with other crops would probably not work well for me.
i gave up picking tomatoes in late June when they all started to look like this. I still had more on the vine, but the stink bugs were an army. I use a hand-held vacuum cleaner to suck up all that I can, but it's still not enough.
This message was edited May 18, 2008 11:39 AM
my back yard is also on the north side of the house--I just don't see those kinds of problems, I don't know what to say except monoculture doesn't seem to help for organic practices
I really think of vegetables as annuals though
my house is a little older, when they made suburban lots larger--maybe 1/4 acre, it would really surprise me if it was 1/2. My beds are real hard to describe--but I do have 1--80' long (that's the width of the lot) 10' wide bed in the back, another 70' long x 10' wide bed also in the back, a bunch of other curving beds in the back and in the front.
On my personal property, right now; I have a peach tree, a plum tree,a lemon tree,a key lime, a mexican lime, bush beans, pole beans, tomatoes, peppers, eggplants, squash, a bunch of herbs...I think that's all the edible things I have right now. Fall and over the winter is when I grow the vast majority of different edibles (all kinds of lettuce except iceberg, spinich, kohlrabi, onions, heirloom Louisiana garlic, leeks, carrots). I do fall tomatoes too. I grow much more non-edible than edible stuff. My next door neighbor has oranges, satsumas, persimmons, kiwi's, jujube's and some other fruit. So I don't have to grow those.
I got one of those websites too--but I'm not here to self promote.
Feldon, I was very impressed that you have tomatoes and potatoes already. On a whim I ordered potatoes this year in the fall because they always look so intresting in the heirloom pictures. They were "spring shipped" and arrived in April from Maine. Are they a lost cause??? The books say to keep piling dirt/mulch on them as they grow. How much green do you leave at the top when piling?
Debbie, I have looked at your website too and you have some BEAUTIFUL flowers. I also enjoyed the picture of your bed with the tomatoe in it. What does the rest of your yard look like and how do you arrange all the fruit trees and vegetables?
Hastur, sorry to take over your thread. Hopefully you can learn from my mistakes...
Tabitha
Tabitha--there are lots of pictures of all my beds, just mostly on the other forums on Dave's and everything in the PlantFiles was from my property, I have tomatoes now too.
I can't take pictures out back right now because I'm watering, I suspect its never going to rain again. But here are a couple taken to show other things so you'll have to look for the vegetables. This one was taken to show someone the back fence which the HOA is supposed to replace (there is a road behind my property) and is at least a week old. It was taken to show a perspective (height wise) of how tall some 2-3 Cape Glad species and Hippeastrum species seedlings were performing in the ground. This bed doesn't show a lot of color until mid-summer and there's lots of things in there. The second pole back shows some cucumbers about 3 weeks old and back behind the 3' Hamalia patens is 4 large squash plants. The vine in the foreground in definitely not something to eat. And all those bags of mulch I can thankfully say are history now.
same bed another day looking east--the tall burgundy-leaved tree behind the rangoon creeper is a plum tree which I may, or may not, remove when the back fence is removed--right now its holding up part of the fence. Normally there are guy wires from the posts on the back fence to the posts by the brick path (you can see the rust from them on the front post of the first shot). Normally there would be cucumbers all acrosss that first trellis in this shot--my hands are kinda tied here until August. Its OK though, because I successively sow cukes all summer.
I'll show you a couple of others another day--there are a few peppers down between the rangoon creeper and the plum tree, they like a lot of shade July-Sept
Normally I don't take pictures of the vegetables, but if I think about it next week I will. These 2 were taken to show somebody on another DG forum the pathetic and herculeon efforts I'm having to take to protect and grow some rather valuable bulbs through this fencing nightmare.
edited to add I was almost stepping on the squash to take this pic
This message was edited May 18, 2008 7:11 PM
Do you hang string from the top and let the cucumbers grow up? What are the spiral shaped poles for? I bought two on sale, but haven't totally decided how they would best be used. I am trying to grow a cucumber up one right now, but it is protesting.
No--the spirals will work until it grabs on to that pole (which its already done)and then the 2 x 4. The spirals were a gift from a friend 3 years ago, they are steel and more substantial than they look; but mainly I just use them as yard art and to grow some short, orderly vines on, I have 12 of them and they are scattered around the beds mainly as structural art. I don't use string--I use steel guy wires normally, I can't put them up right now because any day now they will be tearing that back fence down for replacement. So I'm using 2 spirals as a bridge up to that 2 x 4 for the cukes right now.
That other vine is large and vigorous (I'm having to chop it back literally every other day to keep it under control). String is not strong enough for either of those trellis'. The guy wires run perpendicular (at 90 degree angles) to the support posts every 6". You can see the rust from them on the back fence. Then there is a single guy wire which runs right above the edge of that brick walk between the 2 support poles (normally). That is to give the Rangoon creeper yet more room--that vine is semi-tropical and freezes to ground level every winter--that's why it wasn't very large in the photo.
I will take a picture when that is completed to show you better what I mean.
I will just say that I did not take and post all of those pictures because I think I am successful. I posted a bunch of pictures because I like to take pictures and go back and review them to see what I did wrong and learn from them. DG only allows posting one picture at a time, and I take hundreds per year since I don't have to pay for film. :)
There is a minimum number of tomato plants I want to grow each year. I love most vegetables and plan to continue to grow many different types of crops, but tomatoes will always be prominent. I hand-pick stink bugs and use a dustbuster to get as many as I can find, but I do plant rather intensively as far as plant spacing, so there are lots of places for stink bugs to hide.
Planting potatoes in April does sound like a lost cause. I am not sure why they would send you potatoes 3 months late. I would be curious to know what potato seller this is as clearly they do not understand climates! :)
I planted potatoes January 15th and they are pretty much done by May 1st. High temperatures affect the plants, the flavor of the tubers, and I would guess open the door to many diseases. At the farmer's markets around here, we're seeing the bulk of the potato harvest. For areas North and West of Houston which are a bit cooler, mid-May is peak harvest time for potatoes. Also it has been a very mild year.
I have not had what I would consider "success" with potatoes yet. I've grown them twice and got some good harvests, but not the output I had hoped for. I know the advice on hilling varies depending on what source you read. Some people say hilling more than twice is unnecessary. I did dig down almost to the clay and planted and then added a few inches of soil. Then once they broke ground, I started hilling them up so there was a total of about 1 foot of soil above the tuber to the soil line.
This message was edited May 19, 2008 2:45 PM
If you like to learn from books, the River Oaks Garden Club book is a fantastic resource to have.
I like books, but mostly just check them out from the library...more money saved for plants.
I will see what the potatoes do. I bought them for my garden at school so the kids can see where potatoes come from. Can you buy heirloom potatoes locally to plant in January, or do you have to order them. Can I "harvest" potatoes from this year and save them to plant again?
Feldon your site is amazing, how you get so much from such a small area is beyond me! I'm the one who's tomatoes aren't getting enough sun. They are beautiful, just not much fruit. I have so little sun that I'm thinking of putting EBs on wagons and chasing the sun around the yard LOL!
I'm hanging on to my c-tex seeds though, hope they will be ok for spring! They are going right in the middle of my front flower bed LOL. Thanks for the inspiration and ideas Debbie!
For the location and sun and money I've spent on amendments, I'd say I am getting average to above average output. If all the tomatoes which have set out there reach maturity, then I'll get about 400 non cherry tomatoes out of 30 plants (excluding my plants in containers which had a poor soil mix), which I am extremely satisfied with. Last year I averaged 5-6 tomatoes per plant.
Beans are doing well. Cucumbers I haven't gotten the output that other people report (having to pick every day), but maybe this year will be a good one. I am mulching well, and the plants are mounded up high.
I'd love to try some corn in Earthboxes as Tplant is doing.
I really want to take one of this year's tomato beds and "give it a break" by growing lettuce, broccoli, etc. this fall. I've already bought 50 feet of summerweight row cover to keep the bugs and pests out.
This message was edited May 19, 2008 11:55 PM
If I were growing all what you call reliable varieties like Jet Star, Arkansas Traveler, Gregori's Altai, then I would have a ton of tomatoes. So far in 3 seasons, these 3 varieties have produced 20-30 fruit per plant and this spring is no exception.
You asked about tomato seed longevity. Tomato seeds if properly processed (fermentation or Oxiclean) and stored in a dry place, they should remain highly viable for 5-7 years and less so for another 3-5 years.
It's an old farmer's tale here (but since the old days, has been proven), that you should rotate your tomato crops every year. Don't continuously plant them in the same area. I can't remember the reason (soil disease, lack of nutrients, etc.....but I'm sure someone here will know and speak up).
Personally, I have 9 tomato plants right now. Only 5 varieties. 2 of those plants are in the same spot I had tomatoes last year and they are not doing well. I'm not sure if it's from the overlapping crops or, perhaps I didn't add enough cotton seed meal OR, we had a weather report of a possible late frost and I covered them that night....they haven't been the same since
Regardless, last year I had a huge crop....way too many for us to eat. I choose plants for the taste and the production. Maybe I just haven't tasted enough but, if I only got 5-6 fruit per plant, it wouldn't be worth my time or make a dinner for the table. I know that certain types are small producers and I give a high five to you, Feldon, for keeping those heirlooms going. I don't have the patience, (or the room) so I appreciate learning from someone who has a passion for it. I'll live vicariously though your plantings! LOL.
Regarding stinkbugs, I'll try anything. I like the idea of a dustbuster (hadn't thought of that).
There are a couple or three good reasons to consider rotating your tomato crop, if you have the room and interest/time to do it, especially if one is a casual grower and grows around 5-20 plants or so. It is certainly not a "must do" in most cases, though.
For those of us who grow lots of plants, it's usually not practical, and we still manage to have good success by regularly amending the soil, doing good garden cleanup, and mulching.
One reason that comes to mind are root knot nematodes. The RKN population tends to build up over time in areas where tomatoes, cucurbits, and other "host" plants are regularly planted, and is usually (not always) seen in sandy soils. Letting an area lay fallow or planting "non-host" plants for a yr or more can definitely help *if* this is a problem. Many folks in Tx do not have a problem with 'todes (a sure/unmistakable sign of todes is root galling - if you don't see root galling when you pull the plants, then you don't have 'todes), and if you don't, then no need to worry about it. Nematodes are a toughie, if you have to deal with them (I do). Std/common recommendations to plant cover crops of rye and marigolds usually do little good. Generous and regular additions of organic matter help A LOT if you can't rotate. I am also having good success by pretreating with Dazitol (a mustard/hot pepper based product).
Another reason to rotate might include soil fertility. However, this is easily rectified by regularly amending the planting area in the late fall to early spring with manure, compost, shredded leaves, or other organic matter. IMO, tomatoes need to be grown in good to excellent soil with good tilth/drainage, if you can. ( I prefer raised beds myself.)
Yet another reason might be fungal spores that are shedded by prior year plants from early blight or septoria leaf spot. However, both EB and septoria are non-systemic fungal diseases, and infect the foliage. Good garden cleanup and thick mulching helps to keep soil splashback (and fungal spores) onto the plants to a minimum. So does turning the soil when you do your prior yr cleanup, as it helps to bury the fungal spores. I've found from sometimes growing in the same area from one year to the next, and sometimes not, that there is little difference in the amount of foliar fungal disease I have a problem with. Both EB and septoria spores are "in the air" and can land on your plants and attach to the foliage even if you plant in a "clean"/new planting area (or even in containers).
As for systemic (soil borne diseases), we tend to have few problems with them in Texas. For systemic/soil-borne disease, crop rotation tends to be a common recommendation. However, fusarium and vericillium (systemic fungal disease) and bacterial wilt (also systemic), though not unheard of, are not prevalent in the area.
Most of the prevalent/common tomato diseases in Texas tend to be the foliar fungal diseases - early blight and septoria spot, and occasionally bacterial speck (also non-systemic). Nematodes (which *are* soil borne/systemic) can also be a problem for some, as I've mentioned earlier.
I guess in short I'm saying it doesn't hurt to rotate if you can, but it does pay to attempt to identify any disease problems first. :) May or may not be necessary or helpful.
Myself, I do nothing but heirloom tomatoes anymore, and have excellent production from them; cucumbers are also very productive.
I grow only 3 hybrid tomatoes. Sungold (a yellow cherry which is unequalled), Jet Star (a medium orangish-red hybrid from 1948 which is 2 weeks ahead of everything else and has very good flavor IMO), and Brandy Boy (a hybrid of Brandywine which is supposed to be more productive -- trialing it for the 2nd year). Everything else is open pollinated some of which are heirlooms.