April in Your Greenhouse

Brian Bill

Brian Bill | March 30, 2022

April in Your Greenhouse

Pay no mind to the fact that this blog is dropping on March 30th, this is indeed the blog to read for information regarding April in your greenhouse! Spring is in swing right now and we are starting to see a lot more of our friend, the sun. This newfound day light and warm weather is perfect for starting your outdoor garden, transplanting the seedlings you started inside your greenhouse last month. But what about inside your greenhouse? Don’t worry, there’s still plenty to do inside to keep you busy all season long. This time of year is when you can really get creative with your greenhouse! The extra sun and warmth means we save money on heating and artificial lighting. Though you will have to increase the amount of water and fertilizer you’re using, so that will offset some of your savings. But worry not! If you live in the Pacific Northwest you should have no trouble setting up a rain capture system that would provide more than enough water for your greenhouse. Just a little money saving tip for you there. All that aside, its spring time people! The winter is finally over! Though it wasn’t particularly harsh, especially when compared to the New England winters of my youth, this past season seemed to drag on far too long. Perhaps it was the month’s long lack of sunlight that brought about a general malaise, maybe it was just because I didn’t go skiing enough, but that’s my own problem. Whatever it was, it is over now! In a few days the fields of Skagit Valley will be filled with color as the tulips begin to bloom. I’m sure I’ve mentioned this before on a previous blog, but the Skagit Valley Tulip Festival is a treat and lasts the entire month of April. Massive stretches of normally nondescript land explode with vibrant hues of yellow, purple, red, pink, orange and green in a wondrous rainbow of flowering bulbs. It really is a great way to welcome the spring season and serves as a great excuse to get out and explore the greater Mt Vernon area! You can even buy your own bulbs to plant or fresh cut flowers to decorate your living space. Whether it be flowers, vegetables, fruit or anything else in-between, this is the time to get busy in your greenhouse. A busy and productive spring can set you up for a bountiful and rewarding summer.

If you’re just getting around to gardening now, you’ll likely be worried about starting seedlings. If you want to start multiple plants all at once but don’t have a seedling propagator of your own, a homemade solution might not be far off. If you buy eggs that come in a cardboard container, you’re in luck! Once you’ve used all your eggs go ahead and fill the bottom half of the egg carton with potting soil. Place a few seeds in each little cell and set them in a sunny spot, misting when necessary. This will not only give your seedlings individual spaces in which to grow and develop root systems without competition but then can also be planted with the seedling when it’s ready. Simply cut carton into individual cells to ensure each seedling is on its own and plant them how you normally would any transplant, leaving space for the plants to grow. The cells will keep the rhizome protected until it is strong enough to permeate into the surrounding soil. The cell will eventually biodegrade into the soil and the plants will grow up big and tall.

As I mentioned in the opening paragraph, it’s flower season! Some of you might have them blooming around your yard, some might drive past cherry blossoms on their daily commute, I personally have fresh cut flowers decorating my home. No matter how, more likely than not, flowers are in our lives more and more as spring rolls on. You still have the option to plant some bulbs this time of year, (see the Flowering Bulbs blog for more info) but if you were proactive, you should be seeing tons of in bloom flowers right about now. Daffodils, tulips and hyacinth are pretty much unavoidable this time of year. More importantly though, why would you want to avoid them? They’re beautiful! Flowers just bring a certain brightness to any room or scenery, who doesn’t like flowers? If you were indeed proactive, enjoy your bounty. If not, a fun little trick is to stagger your planting so not all of your flowers come into bloom at once. If you do this, you’ll have sustained flowers blooming for the foreseeable future.

April is a great time to repot your house plants! I’m sure you’ve got something around the house or in the greenhouse that could use a bigger pot, or perhaps it just needs to be trimmed back. April is also a great month to take some cuttings! Repot your azaleas, camellias and other shrubs after they’ve finished flowering. Increase hydrangea growth by providing extra water and fertilizer as you would most plants this time of year. Repot your orchids as needed, keeping in mind that most types enjoy being root bound. Sow zinnia, nemesia, marigold and any other bedding plants you haven’t started earlier. This is also a great time to start some hanging baskets! Mature seedlings and cuttings are great for hanging baskets!

If you’ve got some extra space or don’t feel like growing flowers this year, cool temperature veggies are great to grow this season! Double check the specific seed packet for whatever you plan to plant to double check time frames and planting instructions, but now is a great time to sow bedding plants. If you started early in the year, runner beans, French beans, celery, squash, pumpkins and cucumbers should all be ready around this time of year! Other things like egg plants might not be ready to harvest, but they should be about ready to transplant to either a larger pot or into the ground if you’re confident about frost being an issue of the past. You may also be ready to harvest carrots, lettuce, chicory, cress, radish, mushrooms and other cool crops you may have started earlier in the year. Like I said before, this is a great time of year to get started, but those who were proactive should have plenty to do outside of starting seeds.

Tomatoes! Sorry for the abrupt start, but this is tomato season! They might not be ready to harvest just yet, but if you want to have some tomatoes this summer you better be ready to do some work now! Be sure to transplant the tomatoes you started earlier this year once they reach around 6”-8” in height. Move them to larger pots or your greenhouse beds for best results. When the flowers begin to open up, tap the supports you’ve tied the plants off to in order to aid the pollination process. Alternatively, if your plants are in moveable pots, place them outside during sunny days to attract pollinators to your garden. Water your plants around midday, this is when your plants will be experiencing the most intense sunlight and heat so they will be at their thirstiest. Take care not to spill water on the foliage, as best you can, to avoid promoting fungal and mold growth. Harden off any plants you plan on planting outdoors come May. Make sure you pinch off any side shoots so your plant focuses on the main shoot. Once the fruit begins to form, make sure you increase the frequency with which you are using fertilizer. Once a week is the general standard during fruit formation.

If you plan on doing some other fruits, like melons and grapes, things will be a bit different. If you are hand pollinating these plants, the best practice is to transfer pollen from the anther to the stigma with a soft brush. Do this around midday for a few days in a row to achieve best results. Sow any melon seeds now if you haven’t already. For those you have already started, transplant melon seedlings in early spring to your cold frame for hardening off to ensure it is hardy enough to grow to maturity. If you are looking to reactivate grape vines, use a cold greenhouse, close the vents and increase watering. Do this for a few weeks and your vines should be back and ready to produce. This last bit I probably don’t have to tell you if you’ve been looking around in your garden at all, but, harvest your strawberries!

Climate control in April starts to get a little more complicated than usual. Normally you think the sun would be awesome for plants! Well, not always. When starting off seedlings, direct intense sunlight can actually harm plants. Having a shady spot within your greenhouse or having shading handy is a must this month. Even something like some newspaper, if anyone still has those, can help keep your plants from burning. Remove the insulation you put on your greenhouse to protect it from the winter’s cold. Your heater will become less and less useful as summer approaches, but there is always the threat of a random frost, so be careful. Greenhouses are supposed to be warm, but not too hot nothing can survive in it. Plants can be just as sensitive to heat as they can cold. Make sure you are staying on top of venting and air circulation as the warm weather can bring with it some issues. Warm temperatures, stagnant air and moisture is the perfect climate for pests and mold which can ruin your greenhouse experience. If you really have some extra time and want to save yourself some planning next season, record the daily highs and lows this season. While the climate is not going to be the same year to year, especially not these days, but it should be similar enough. You can use this information next year to tell you when the best time to start planting is. If you can map out a predicted microclimate for your greenhouse, the planning stage for planting and growing becomes that much easier.

Yes, there is quite a bit to keep track of this month, but it’s the start of gardening season! What were you expecting? These dahlias aren’t going to grow themselves! Well, they certainly won’t plant themselves… It’s that time of year again so don’t be afraid to get out there, absorb some Vitamin D and get your hands dirty! Until next month, thanks for reading and best of luck this April in your greenhouse.

-Brian Bill