Recently, Ã‚Â I received an email from a customer in Maine asking about the need to fertilize in the fall and about what needs to be done to the strawberry bed to prepare it for winter. The customer also wanted to know what would happen if late season fruit were not picked. Here are some general comments sent to this customer who grows ‘Alexandria’:
IÃ¢â‚¬â„¢m glad to hear that your plants are still producing. Even frost wonÃ¢â‚¬â„¢t stop them. A hard frost will kill off the new blooms but fruit already set will continue to mature as weather allows. IÃ¢â‚¬â„¢m in zone 7 here and have picked as late as Christmas Day.
First, IÃ¢â‚¬â„¢d suggest that you get hold of winter protection info specific to your area. County Extension usually has good info. Even though their info is about hybrid garden strawberries it applies to alpines.
Ã¢â‚¬ËœAlexandriaÃ¢â‚¬â„¢ are day neutral ever bearing types. They donÃ¢â‚¬â„¢t need cold temps to set next yearÃ¢â‚¬â„¢s crop. Get them through winter and they will set a new crop.
I do not recommend fertilizing in fall. Wait until very early spring when the straw mulch has been removed. Fall fertilization can lead to new tender growth that makes the plants susceptible to winter kill. The plants will grow, mostly underground, even in winter, though very slowly.
I recommend a wheat or oats straw. Some recommend corn stalks. Even though there is a lot of corn here, IÃ¢â‚¬â„¢ve never had access to any to try. IÃ¢â‚¬â„¢ve tried leaves. They matt down and smother the plants. IÃ¢â‚¬â„¢ve had near 100% die off when using leaves.
I use about 3-4Ã¢â‚¬Â of straw. I apply it after a couple of hard frosts. The plants need to be preconditioned in a way, prepared for mulching. If lush green plants are mulched the leaves pack down and get moldy which leads to diseases, etc. The best time for that here is late November to mid-December depending on the season. In your area I would guess mid to late October.
In early spring, take the mulch off when the daytime temps get into the low 40Ã¢â‚¬â„¢s. Even though it will still freeze at night, the plants will begin to grow. You donÃ¢â‚¬â„¢t want to leave the mulch on too long, especially if itÃ¢â‚¬â„¢s an extremely wet spring. The plants need to dry out a bit to reduce diseases. Add compost or fertilizer when the mulch is taken off. Work it into the soil a bit as best you can.
I like to leave an inch or two of straw around the plants and a lot between the rows. This helps to protect the fruit from dirt splashing and helps it to dry off quicker. It also holds soil moisture during the season and holds down weeds. Alpines need to be able to expand their plant size so donÃ¢â‚¬â„¢t leave too much mulch on them or it will suppress their expansion and growth. If the mulch is kept loose near the old plant, new crowns will be able to find their way out. This allows the mound to expand and significantly increases production. Next springÃ¢â‚¬â„¢s crop should be huge.
You mention not being able to pick the fruit. With a single variety it shouldnÃ¢â‚¬â„¢t be a problem. With multiple varieties they will cross. The cross pollination doesnÃ¢â‚¬â„¢t affect the taste of the fruit but fruit left behind will not be genetically the same as the parent plant. Volunteer seedlings will sprout and eventually, after a few years, could take over. These volunteers can even be runnering types. ItÃ¢â‚¬â„¢s best to keep them picked as best you can if you have more than one variety or if there are wild Fragaria vesca in the area that could cross with your cultivated plants. A few fruit left behind is not a problem. Many left behind could eventually shorten the life of the planting.
One last thing. Make sure that the soil doesnÃ¢â‚¬â„¢t dry out completely during winter. Very dry winters where the soil is bone dry will cause winter kill. In extreme cases the plants should be watered to bring up soil moisture.
Sorry that itÃ¢â‚¬â„¢s not more straight forward with exact dates to apply mulch, etc. ItÃ¢â‚¬â„¢s an art rather than a science. After doing it for years I know the day it needs to be done. When heavy rain or snow and cold temps are coming, after a couple of hard frosts, itÃ¢â‚¬â„¢s time. I hope that helps you.