Hey Dr. Y...First off, it's my pleasure to respond to these forum posts. I saw a few key phrases that raised some red flags: "clay soil", "an inch of rain every week...", "no sign of disease"... The fact that you didn't see any signs of disease makes me think that you probably shouldn't use any fungicides or pesticides. You mentioned that the raspberries are planted on a hill side, which usually means the soil will drain well; however, you also mentioned that it was clay soil. There is likely a clay pan that all that rain couldn't penetrate easily and there was some stagnant water. The combination of clay soil and lots of rain can be a bad one. Also, members of the rose family, which raspberries are, are known to have trouble with pollination when it constantly rains.

Hey Kadra...You can likely go to a hardware store, garden center, or even a hydroponic supply store. Sounds like your grandma has an incandescent grow light bulb, which is what I would ask one of the associates at the store to help you find. Generally, these lights are used as supplements to natural light and will not completely replace them. There are other types of grow lights, but these require special manifolds to house the bulbs. An incandescent grow light bulb will fit in a normal light socket. The important thing for these grow lights is that they produce relatively more colors in the spectrum of light that the plants use for photosynthesis. Those colors are specifically red and blue. The light may still look to be white when you look at it, but it should be producing more red and/or blue light for the plants. I'm not too sure where you can buy these bulbs online, but I'm sure a simple web search on "incandescent grow light bulb" will result in some fine sites. I hope this is helpful. Let me know if you have any further questions...Dr. Robby

Hey Kadra...the 1/2 full bag of left over soil should be fine to use. I would pre-moisten the soil however. The old soil could have dried out considerably and sometimes wetting it can be troublesome. Also, if it's so hard that it has become a brick (or at least very hard), be sure to break it up some. You don't want the old soil to become a cement for your plants. If you fear that the old soil will not be able to provide the drainage that your plants probably will need, go ahead and purchase some perlite, sand or pumice pebbles. You can treat your soil with these amendments to increase proper drainage and air porosity. Also, if the old soil was impregnated with any kind of fertilizer, that fertilizer may have broken down, leached out, etc...You may want to add a little fertilizer (go light on the fertilizer at first) when you use this soil. I hope this information is helpful. Let me know if you have any further questions. Cheers...Dr. Robby

I hope this is helpful. I apologize for the long diatribe on anything that could've caused a fruit production reduction in your raspberry. There are many possibilities, but my money would be on soil status. Of course if you have any further questions, please ask. I will try to keep it shorter next time. :) Cheers...Dr. Robby

Having said all this, my final advice comes from my first post on this issue. Raspberries do best with constantly moist soil that drains well. If your soil does not drain very well (there is consistently standing water after you water), then this may cause the issue. Also, standing water increases the humidity around your plant, which in turn increases the chance of fungal disease infection. Also, if there was a quick bout of water stress during the flower development, you could see the flower abortion. Basically, when it comes down to it, fruit production is a costly process. Flower abortion can be a result of many kinds of stress. By aborting the flowers, the plant will cut its losses before too much is invested in the next step (fruit production) when the plant is experiencing some type of environmental stress.

Finally temperature may also be an issue. There was an article in Scientia Horticulturae long ago that discusses flower abortion at different temperatures. Although the model plant for this paper was different from raspberry, it is known that rapid temperature shifts can cause havoc on flower production in plants. Generally this is not an issue since raspberries generally flower in late spring through summer, but if there was a sudden temperature shift in either direction (colder or hotter) you may have an issue.

Mildew can also cause floral abortion. By chance did you notice any gray fuzz on any of the leaves last season? If you did, my recommendation would be to increase the air flow through the foliage by doing some maintenance pruning. By pruning away some of the canes, you will promote better air flow through the canopy which in turn decreases the chance of fungi infection.

Plant nutrition may also be an issue. Plants can abort their flowers if there is a boron toxicity. As random as this may sound, it actually happens more often than one would think. Also, too much nitrogen can cause a drop in flower/fruit production, but once again, this would not be manifested in a drop off of the flowers.

Another issue may be pruning, however, this is complex. Different varieties of raspberries require different types of pruning. Generally, red and yellow summer-fruiting varieties should be pruned right after harvest, whereas purple varieties should be pinched in early summer before harvest. Pinching and pruning are different and result in different outcomes. Since I am not sure which variety of raspberry you have, I cannot truly give you good advice with this issue. I may be able to help you more if you know which variety of raspberry you are growing.

Pollination could also be a factor, but once again I do not think this to be the case. Raspberries are mostly self-fertile and do not require pollinators to produce fruit. Raspberries that lacked any pollinators (bees more often than not are the pollinators) will show a reduction in the amount of drupelets per "berry". Drupelet is the name for the individual fruits...there are many drupelets per "berry". There will also be an overall decrease in the number of "berries" produced.