Strawberries


As we start our third growing season at Road’s End Farm it is time to write about some of our observations and results with the many types of fruiting plants that we grow.  As you know our mission is to develop and promote varieties that are suited to culture in the central New Mexico mountains and similar locales.  We want you to be successful by helping you choose varieties that will profitably produce for you.  Our method is simple in that we take our best educated guess from years of growing, listening to others experiences and add some of the latest varieties to the mix.  We then grow these and see which do best or in some cases do poorly.

Of course results may vary depending on the care, location, microclimate etc. that you give a certain plant.  In those cases we will make recommendations for location and culture.  Our plantings are not babied as you might do at home. They are planted in the field with no shade and treated as a commercial crop would be.  In many cases the planting stock we have purchased has been very small, maybe suitable for a 4” container or was a 4-6” bare root plant.  Such is the way of dealing with new or rare varieties, they just may not be available in a size we would prefer.  Often is the time we felt a larger plant would have survived or thrived whereas the smaller one could not adapt. We will discuss these possibilities as we go through our series of posts.

For those of you more detail oriented, the soil ph at our farm is 8.2 which is considered very alkaline.  Our water comes from fractured limestone and also has a high ph and is very “hard”.  February 2010 recorded minus 34f and summer 2011 recorded a high of 102f.   Most research on “hardiness” of plants is focused on the coldest temperature they can live with and very little research has been done on the warmest temperature they can take.  When we make selections to trial we find ourselves choosing from varieties that may do well in the upper great plains or in Russia’s colder areas. In the case of heat we will discuss it when it applies.  I hope to be able to cover at least 1 fruit type a week in an informal and unscientific manner, but this time of year is always short on “spare writing” time so don’t hold me to it.

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This year has not been a very good one for berry production in Central and Northern New Mexico.  We just picked our first crop of fall raspberries last Saturday the 24th.  This is running 1 month later than the start of berry season last year.  Gardening and growing is a constant process of trial and error and evaluation as we all try to assess what we did right and what went wrong.  Hopefully we can get the “rights” on our side with a minimum of “wrongs” so that we can be more productive, and for growers have a better income.  All of our fall bearing types of berries will produce until the first hard freezes.  It appears that this year the late season will cut the actual total harvest by more than 50%.  I have consulted many growers, state experts and also done research to see if I could find why this happened this year.  Virtually all of them agreed the crops were late and blamed it on our late spring (May) freezes.  When pushed for their reasoning it was basically that the plants got a “late start” in coming up because of the late cold.  Some blamed it on the extreme freeze in February also.   

At the risk of being considered a heretic and going against conventional wisdom, I believe there is another and more logical answer.  In fact, I believe it is the exact opposite of what my contemporaries think.  I am convinced the maturation and late harvest was caused by the record heat this summer.  New Mexico had the hottest August on record this year.  We also had very little monsoon rains to temper and cool the hot afternoons days with either rain or clouds. In regards to late freezes, yes we had them and our last one was on May 16th this year. However consulting my records shows that last year 2010 our last freeze was May 25th,  9 days later than this year! 

Most plants grow best between 55 and 85 degrees Fahrenheit. Berries are considered to prefer the cooler temperatures. Plants will produce maximum growth when exposed to a day temperature that is about 10 to 15°F higher than the night temperature. This allows the plant to photosynthesize (build up) and respire (break down) during an optimum daytime temperature, and to curtail the rate of respiration during a cooler night. High temperatures cause increased respiration, sometimes above the rate of photosynthesis. This means that the products of photosynthesis are being used more rapidly than they are being produced. For growth to occur, photosynthesis must be greater than respiration.  When increasing the temperature above 85 most plants will stop growth. Add to that a lower humidity and they will attempt to go dormant to conserve their resources. 

In essence I believe the August heat basically put the berry plants “on hold” effectively stopping almost all growth.  This was confirmed by visual observation although no measurements were taken.  Plants all looked good, they just didn’t seem to do anything.  If it had affected just raspberries, I might look for another cause, however since the exact same thing was observed in all varieties of our raspberries and all varieties of our strawberries along with Goji berries I really think this is the answer.  We clear cultivate next to our raspberry rows, which leaves bare dirt and of course this is much hotter than a grassy cover.  It would have been interesting to turn a sprinkler onto some of the plants for 2-3 minutes a couple of times daily and see if cooling them off helped or changed the delayed harvest. 

Next year we will mulch half of our raspberries and see if that does the trick by keeping the surrounding soil temperature lower.  In the meantime we will enjoy eating all we can get of these great tasting berries!

 

Iron Chlorosis is the most common micro-nutrient problem of fruits in New Mexico.  It is the result of the inability to extract sufficient iron from the soil, but not usually caused from a deficiency of iron.  New Mexico soils generally have plenty of iron especially in the red soil or red rock areas.  Iron is required to produce chlorophyll which in turn is what feeds the plant and promotes growth.  It appears as a yellowing of the leaf tissue between the veins.  In severe cases it will cause the leaves to turn a very pale yellow and possibly even white if it is past “severe”.  At first glance it can resemble a nitrogen deficiency but is distinguished in 2 ways.  With iron chlorosis the veins of the leaf will remain green. Nitrogen deficiency will turn all of the leaf yellow.  Also iron chlorosis starts with new leaves and nitrogen deficiencies first appear on the older leaves.

 The underlying cause is a high soil ph, which is what most New Mexico soils have.  Different plants and varieties within a species have different levels of tolerance.  Fruit crops are among the most sensitive plants to this problem.  In our experience the most susceptible types in order are: strawberries, blackberries, grapes, raspberries and apples.  Mild cases will result in poor growth, poor runner or new cane/branch production and poor quality and flavor fruit. Severe cases will result in plant death.

 As the soil ph increases the solubility of many nutrients is reduced. As a result these nutrients are precipitated as solid materials that plants cannot use.  For example the solubility of iron is 100ppm at a ph of 4, but drops to only.01ppm at a ph of 6.  At ph levels above 7.5, the amount of iron is often too low to sustain healthy plant growth.  While generally we have more iron in our soil than needed it may be in an unavailable form due to high ph.

 Plants differ in their ability to tolerate high ph soils.  In moderately alkaline soils, some plants can secrete high amounts of acids into the soil.  This lowers the ph immediately around the roots and increases nutrient availability. As the soils ph increases to 7.8 even these plants experience nutrient deficiencies. 

 There are many contributing factors that can bring on iron chlorosis and the interactions of these factors are not fully understood.  Plant competition, winter injury, soil compaction, excessive soil salt levels, excessive organic material, extreme soil temperature and light intensity and over watering can all lead to or aggravate a chlorotic situation. One common cause is the incorrect application of N-P-K chemical fertilizers

  How to Prevent Iron Chlorosis –

 Start with testing a good soil test. If you don’t know your starting point you won’t know how to get to where you need to be.  Check the soil ph and also the ph of the water you will be using to irrigate with. If you are in the 7 – 7.5 range you probably will not have any issues. If above 7.5 do the following. 

  • · Start your bed 1 year ahead of when you will plant it
  • · Use vegetative compost, no animal manures as these increase the soils salts levels and can aggravate the situation.  Try to achieve about 5% organic matter. Stable compost and the associated biological activity have a buffering affect on the ph.  
  • ·Flood the bed several times to leach accumulated salts below the root line.
  • ·If your soil does not have free lime add elemental sulfur.  A simple way to test is to take a teaspoon of the soil and dampen with vinegar.  If the soil fizzes you have too much lime for the sulfur to be effective. The bacterial action on the sulfur produces sulfuric acid which lowers the ph.  Sulfur will take around 6 months to start to become effective.
  • ·Add peat moss to your bed and mix in thoroughly.  Peat moss has a very low ph and will help bring it down in your soil.
  • ·Choose varieties that are known to be less sensitive.  In strawberries we have seen Sparkle a June bearer and Albion an ever bearer to be very susceptible to chlorosis.  Honeoye as June bearer and Seascape as an ever bearer are much less susceptible and better choices for New Mexico.

How to Deal with Iron Chlorosis if it Shows Up –

 The vast majority of the cases are brought on by over watering! It gets 90 degrees and our plants wilt (which is normal) but we assume they need more water.  We keep adding even more water as the situation gets worse and create a vicious cycle.  At the first sign of chlorosis decreasing the water will usually bring on a cure. The additional water also leaches away the acid environment the roots had developed immediately around them and now they cannot uptake iron. 

  • ·Add liquid elemental sulfur, this will work faster than the granulated as it will immediately get to the root zone where bacteria can use it.
  • ·Add a chelated iron.  This is a form of iron that will stay available longer than iron sulphate.  This may give some immediate results usually within 5-10 days.  If soil is above 7.5ph this may not be effective. Then you will have to use a form chelated with EDDHMA or EDDHA instead of the normal EDTA chelate.
  • ·If the situation is desperate use the iron chelate as a foliar spray.  This is the least recommended as it will take several applications and is a fine line between using enough to be effective and too much that will burn.  Chelated sprays are inactivated by sunlight so application is late in the day or at dusk.

 Again the benefits of a professional soil test cannot be overstated if you are serious about growing good fruits.  NMSU and many private labs offer this service for a reasonable charge.  If you want names or recommendations for labs, email or call us.

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In the first part of this series I told you of some minor changes we made that were part of our tremendous success. They really didn’t require any extra effort and weren’t the most important factors, in my opinion.  Here is where the work comes in and what makes the payoff.

If we take a look at what commercial strawberry operations do for maximum yield, we can get some idea of the direction to take and what to discard.  Basically they treat Strawberries as an annual crop, sterilizing the soil with methyl bromide (now outlawed in the US) or another fumigant and replanting in the same spot. This leaves a dead soil and is nothing really any different than hydroponics when you think about it. The soils only purpose is to hold the roots. All nutrients are supplied in a liquid form via drip irrigation.  We will go a different route on these ideas. We want a healthy soil where the nutrients are derived from the “soil food web” and we want our crop to produce for a few years before replanting.  They then plant in plastic which does several good things. It eliminates weeds and the competition from them (invasive grasses being the worst).  It keeps a consistent moisture level which is beneficial. It helps warm the soil earlier which gives faster and larger plant growth. It does not allow runners to develop or take hold.  Organic certification does not allow the use of plastic for more than a single growing season and it must be removed.  If we were not certified organic, I definitely would use plastic.  We will have to resort to manual weed removal and manual runner elimination to achieve the desired results.

Day Neutral Strawberries

Getting More from Less –  When planting day neutral strawberries you want to get them into the ground before April 15th.  This will give sufficient time to be large enough to crop the same year.  They should be planted about one foot apart and no closer than 9” apart.  Up until July 1st of the planting  year you want to remove all runners and blossoms as soon as they appear.  In my opinion this is the most important factor in growing good tasting, large strawberries. It must be done at least weekly or it can get away from you.  While the idea of free plants from runners is appealing it is really penny wise and pound foolish.  If the “mother” plant is allowed to produce runners it goes into a vegetative reproduction mode.  If the runners are removed then all energy goes into the “mother” plant and then the fruit.  Also plants with runners eliminated seem to often make double or triple crowns.  These  extra crowns produce as much as 2 or 3 plants, so you gain by removing runners.  Luckily Day-Neutrals do not produce as many runners as June bearing so it really isn’t that hard to keep up on.  After July 1st go ahead and allow them to flower and expect to start getting fruit about a month later.  As you are picking fruit at least weekly keep the runners pinched off.  Generally 50 – 75 plants should give you all the fresh eating strawberries you could want for a family of 4.  The next year they will start fruiting in the spring and continue all year. You can allow them to do so. Also at this point you will allow some runners to develop so you can work replacement plants into you plan.

Junebearing Strawberries – These will be treated as above except for the whole first year.  It is best to allow no fruit and very little runner production the first year to maximize the “mother” plant size.  If desired and for economics you can plant on 2 foot centers and allow 1 runner per plant to fill in the row. 

The drawback to Junebearers is they produce huge quantities of runners which must be diligently pinched or snipped off.  The benefit is one huge crop lasting for 2-3 weeks in early summer.  If you are serious about canning or putting them up this is a great way to go as the crop comes all at once.  However after the harvest it is human nature to get busy and let the runners get away from you.  You will soon end up with a matted mess of smaller, and less productive plants.  We find if we are picking each week it is easy to keep down the runners as we pick fruit and for that reason I would rather just grow the day-neutrals.  We are however growing both to see how much we can get for jam, preserves, freezing etc.

At this point in our experimentation we have found the best producing and tasting day neutral is SeaScape. We also tried Albion, a newer commercial replacement for SeaScape but found that it did not grow or produce nearly as well, was more sensitive to soil ph / Iron Chlorosis and had a slightly more tart flavor

For Junebearing we planted both Honeyoye and Sparkle and there is no comparison.  Honeyoye produced big, green healthy plants, while we struggled with severe Iron deficiency issues with Sparkle for most of the season.  Also Honeyoye grew large and dense enough to shade out and suppress most weeds by the end of the season.  We expect next spring’s crop from Sparkle to be severely diminished but we will have to wait and see and then report our findings.

I won’t kid you, growing good strawberries is going to take some work on your part.  The good news is it isn’t a large amount of work or hard work, the bad news is it takes a consistent commitment. After years of failures we have found some key elements that have made the difference.

The Water  The first change I made was in how they are watered.  Strawberries are a shallow rooted crop and the getting the best requires consistent watering. I now believe the only way to water them is drip irrigation, further than that I believe the best is to use a product called T-Tape.  It is tubing with the emitters built-in as opposed to adding separate button drippers.  It is available in several emitter spacings and flow rates.  We used the 8” on center emitters with a slow flow rate.  This applies about 20 gallons per hour per 100’ of row.  The benefit is that the water spreads when applied slowly and ends up consistent along the row.  The next thing is some sort of timer so that they will always get watered when they should.  No matter how hard I tried in the past, things come up and watering became an erratic chore. This way it takes no time or worries on your part.  While it does cost some up front, the pay off is worth it.

The Soil  I think this is the least important aspect.  I know in some circles that would be considered blasphemy, but you really don’t have that much control over your soil in a perennial setting. Virtually all authorities and books will tell you that strawberries need a sandy soil not clay. We grew our berries in the standard Moriarty Muck technically called by the USGS “Witt clay loam”.  It is a  fairly heavy clay, slightly reddish in color that when wet becomes slicker than oil and when dry becomes hard as a rock and cracks appear on the surface.  As long as you have good drainage and consistent moisture that is what seems to be important.

Soil Amendments  I am not telling you to not amend your soil, we did. We initially added about a 2-3” layer of aged manure and rototilled it in when preparing the beds to increase the tilth.  However after about 60 days no matter how much organic material you added it seems to have disappeared.  Because of bacterial action it will have broken down and very little organic matter will have resulted.  If you could continue to dig in more compost etc it would be one thing but from here on for the next 3-5 years this bed is permanent and can’t be rototilled or dug.  I think it is best to annually add compost to the top using a vegetative compost not manure.  Manures will result in increasing the ph and leave behind higher levels of certain salts.  Several of the latest studies suggest that top dressing with compost may not be that effective due to oxidation in the first 1” or 2”.   I don’t have an answer one way or another but tend to believe that since strawberries are shallow rooted the slow fertilization of compost will help along with any organic matter being an improvement in our soils.  That is why I say you don’t really have much control over the soil in these beds.  The real answer as to how good your soil is lies in the number of earthworms present.  If you have earthworms, you are on the right track.  A good soil will have 10 earthworms per cubic foot of soil, so dig in and if you have two or three earthworms in a shovelful, you are doing great.

Soil PH  This is probably the most important aspect in dealing with soil.  Notoriously our PH is high and adding water which is also a high ph doesn’t help.  All books will tell you that 6-6.8 ph is best.  Our ph comes in at 8.2, way too high for my liking.  I recommend everyone get a soil test so they know what they are dealing with and test their water supply. Barring that, purchase a soil PH kit and do your own testing. From my observations anything in the under 8 range will probably be ok with lower being better. The most noticeable issue with strawberries from a high ph is “Iron Chlorosis”.  This looks like nitrogen deficiency where the leaves get a pale yellow and the veins are still green.  If you are not an organic grower it is easily corrected by chelated iron.  If you are certified then you must use sulfur or cottonseed meal to slowly lower your ph.  More about this in a later post as it requires more space to cover fairly.

Fertilizing  We used no fertilizer or compost in this first season save for the initial dig in of manure. Over fertilizing can result in more, smaller berries with poor flavor.  The addition of nitrogen will give lush green plants at the expense of fruit.  Our soil testing showed sufficient amounts of phosphorus and potassium in the native soil and these are what is needed for good root growth and fruiting.

Over the past 30 years I have grown strawberries in Albuquerque, Santa Fe and Edgewood all to varying degrees of disappointment.  I have tried all sorts of methods, amendments etc and always come up short.  I will start out by planting correctly and carefully caring for the plants through our miserable spring weather. By May I am starting to see the reward , the first white flowers!  I know that a month later I will be eating fresh, juicy and tasty berries to the envy of all my friends and family.  I have visions of them still being forced to pay outrageous prices at the store for tasteless and cardboard textured strawberries while I am wondering what to do with my excessive bounty.  By mid May I am reveling in all the runners being produced giving me free plants and even more strawberries next year!  I finally get my first berries which while they taste good enough (not great but good) there doesn’t seem to be enough of them.  I rarely have enough to make it from the garden to the house before they are all eaten.  No matter though, I know this is the first year and the next year when they have matured I will be hauling them out of the garden by the wheelbarrow full.  I continue to care for them with occasional weeding and a lot of watering.  They grow large and rapidly fill in my allotted area with the new plants from runners.  All is well and next year can’t come soon enough.

The next year comes around and the strawberries are one of the first crops to show signs of life.  They start flowering and we soon get our first ones.  Strangely enough we don’t seem to get nearly as many as I thought we would and they really aren’t very large.  If I do get one that is an inch long it is one of the bigger ones. So I end up picking and waiting for them to improve but they never do.  The amount I get at a picking is never enough to do anything with like make a pie or make some jelly.  If I get half of a cereal bowl that’s a bountiful harvest and the flavor, while better than grocery store isn’t really all that great.  Pretty soon they have stopped producing for the year and you move on to other things deciding it just isn’t worth all the trouble.  Sometimes a bed will make it to year three but never through the year before I give up in disgust.  I end up realizing that is why the major strawberry industries are in California and Florida and not in New Mexico.  After all this is a desert that goes from hot to cold to hot to hotter while always being windy. Not exactly a garden paradise.  After a year or two without growing any strawberries the disappointment has worn off and I try again.

By now my readers are thinking that doing the same thing over and over and expecting different results is the definition of insanity.  Let me assure you I have tried a lot of different things. I have flood irrigated, watered with a hose, used sprinklers and tried drip irrigation.  I have grown in full sun, half sun, filtered shade and full shade.  I have used commercial fertilizer, organic fertilizers and no fertilizers.  I have amended soil with sand, manures, peat moss, used topsoil gathered from under pinon and oak trees all the way to using top soil only purchased from Home Depot.  I have tried bareroot plants and live plants. I have planted as early as March and built a plastic tunnel over the bed for protection. I have planted as late as June.  I have grown in the ground, on raised beds, in planters and in wooden raised beds. About the only thing I haven’t done in the past is swing a dead cat at midnight or use a crystal pyramid.  In the end the result is always disappointment.

When we purchased the current land for growing fruit, my partners all wanted to grow strawberries.  With my past history of various strawberry failures I cringed inside.  However I figured after a year or two we could get that out of their systems and use the rows for trees or something else when strawberries proved a disaster.  I tried to talk them out of it but they reminded me of our company mission statement about developing varieties of different fruit that can be grown in New Mexico.   I decided to spend some research time to see if I could improve on my mistakes of the past. This season we grew strawberries and the first year crop was an unbelievable success.  We grew strawberries, more strawberries and even more strawberries. Better than that they were by far bigger than any I ever grew with a taste that was unbelievable.  Finally it looks like growing strawberries can be something other than a disappointment in fact they can be an unbelievable success.  From speaking with many of you this summer, I know you also have had the poor results I have had in the past.   Next post I will tell you what we did that turned things around for us.

There are 3 types of the common strawberry: Junebearing, Everbearing and Day-Neutral.  Commonly in catalogs the Day Neutral are combined with the Everbearing under a single heading of Everbearing.  But beware as they are different in their habits and production.

The Junebearing produce a single crop each year over about a 2-3 week period usually in June.  Within this grouping are early, mid and late season varieties so that by planting different cultivars you could extend the season from June all the way through July (in theory).  It takes about 28 days from initial flowering to ripe fruit and warm weather can induce early flowering in April.  Because of our tendency to get late frosts and even freezes throughout April and May the early season Junebearers could be frozen out so that you have partial or total crop failure. One way around this would be the use of floating row covers but most people do not want to go to that much trouble. I  find that the biggest problem is not so much with the freeze or frost but with the several cold days that are usually associated with it.   Most strawberry pollination is by bees and honey bees will not leave the hive to do their job at temperatures under 55 degrees.  The native bees are somewhat less cold sensitive but you can see that incomplete or inadequate pollination over a few cold days can dramatically reduce yield.  Junebearing strawberries will give their first crop in the year after they are planted.  Junebearers are also notable in that they have very heavy runner production.

The Everbearing strawberries really aren’t “everbearing” as the name implies.  More accurately they should be called “dual cropping”. They produce a June or early crop and then a smaller fall crop.  Each cultivar is a little different as to how close to long days it starts back up production and how long that production lasts in the fall.  Everbearing will usually give a small crop in the fall of the same year they are planted

The Day Neutrals are truly “everbearing” and are the latest in strawberry varieties to be invented. They do not depend on day length to initiate flowering will produce starting in June through summer and fall all the way up to frost. They are notable for having poor runner production.

Your choice of type of strawberry will depend on how you want to use them and your available gardening time.  If you like to make jams, jellies and preserves, along with maybe freezing some for later use then Junebearers are the way to go.  This also concentrates most of your labor for a short period in the summer.

If you want to do the above and also have a few fresh crops in the end of summer then the Everbearers are for you.  If you love and want fresh strawberries available all the time then Day-neutrals are the ticket, just remember you will be picking once or twice a week all season.

Of course the above is dependent on how many plants you are growing and how good your cultural practices are, which in turn can greatly affect size and quality.  For constant fresh eating 50 plants of Day Neutrals will keep a family of 4 very well supplied. If you want extras to can a little and some occasional pies then up it to 100 plants.

Since we have a never ending appetite for strawberries we are growing a June bearing crop so we can preserve the year’s worth at one time and also a Day Neutral crop so we can always have them for fresh eating and sharing with friends.