These tips are simple but can make a big difference when growing flowering plants including sweet pea, peony, lavender, delphinium, lilac, sunflower, hollyhock, foxglove, monarda, and hydrangea.
If you want extended flower times, also see 20 Perennials with Long-Lasting Blooms.
Top Flower Growing Tips
I wish I knew these things when I starting out!
These are not your typical growing tips. Instead, I went through my growing guides for each of these popular flowering plants and selected tips that can prevent future problems, dispel common myths, or help provide a better understanding of what that plant needs to thrive.
There are also links going to the complete flower guides if you want additional information.
As always, these outdoor growing tips are geared toward hardiness zones 4 to 8 (Canada and the United States).
This explains more about the differences between annuals and perennials and why you might want one or the other.
Contents
1Sweet Pea
Top Tip
There are two basic types of sweet pea: annuals and perennials.
Grow annuals (Lathyrus odoratus) and avoid the perennial vine (L. latifolius) which is a highly invasive plant.
Read More: Sweet Pea Growing Tips
Sweet Peas | Genus: Lathyrus
Flowering plant or vine | Tips For Hardiness Zones 4-8
• Annual hardiness zones 7 up
• Perennial L. latifolius is invasive
• Sow seeds indoors 8-10 weeks before last frost and transplant after last frost or direct sow 6 weeks before last frost.
• Fall sowing is also possible in a heated greenhouse.
• Best Light: 6 hours morning sun
• Well-draining soil, rich in compost
• Do best in moderate summer temperatures, not heat
• Cut flowers: 4 to 5 days with preservative in vase water
• Seeds can be harvested for seed saving
Shop Online:
- Sweet Pea Seeds | Botanical Interests (US Shipping)
- Sweet Pea Seeds | West Coast Seeds (CAD Shipping)
2Peony
Top Tips
It’s often said that you can only transplant peonies in fall. Not true. The most important thing is to plant them at the right depth in a full sun location. If yours are unhappy where they are, no sense waiting to move them.
Ever notice how ants are attracted to peony buds and blooms? This is perfectly normal and harmless: it’s the peony nectar they are dining on.
Read More: Peony Growing Tips
Peony | Genus: Paeonia
Herbaceous and woody shrub plants
• Hardiness Zones 2 to 8
• Full sun 6+ total hours per day
• Well-draining soil
• Must be planted at correct depth
3Lavender
Top Tips
The two most important growing conditions for lavender are full sun and well-draining soil.
There are annual and perennial species: many gardeners accidentally buy a tender annual and wonder why it didn’t survive the winter.
- L. angustifolia and L. xintermedia are popular hardy lavenders with many varieties available.
- Lavandula stoechas and L. dentata are annual species.
Not all lavender is fragrant: each variety has different traits. Do your homework first if you’re growing lavender for a specific purpose (appearance, bloom times, oil, fragrance).
Read More: Lavender Growing Tips including how to know if yours is annual or perennial.
Lavender | Genus: Lavandula
Woody herb / Sub-shrub
• Hardy species suit zones 5 to 9
• Full sun 6+ total hours per day
• Well-draining, sandy-loam soil
• Flower colors: white, pink, blue, purple
• Trim flowers after blooming to two-inches above the woody parts
- Lavender Growing Guide
- Lavender dye recipe for fabric
4Delphinium
Top Tips
Name mix-up: be sure you’re growing delphiniums (genus: Delphinium) which are perennials and not larkspur (genus: Consolida) which are annuals. It’s confusing because Delphiniums are sometimes sold under the common name ‘larkspur’.
The secret to successfully germinating delphinium seeds is stratification: a period of exposure to cool, damp conditions near freezing to prepare the seed embryo for sprouting. You can do this using your fridge.
Read More: Delphinium Growing Tips
Delphinium | Genus: Delphinium
Herbaceous perennial
• Hardiness zones 3a to 8b
• Full or part sun
• Well-draining loam is best
• Native to North America and African mountains and considered non-invasive
• Chill dampened seeds prior to sowing for better germination rates
- Delphinium Growing Guide
- Shop Online: Buy delphinium seeds at Botanical Interests (US shipping)
5Lilac
Top Tips
Depending on the variety, lilacs can grow as shrubs or full-size trees ranging in size from 6-feet around to 35 feet tall. Choose carefully!
While some lilacs may never need pruning, you may want to deadhead (trim off dead flower heads) right after blooming to clean up the appearance and make room for new blooms. Pruning is a separate process primarily for removing dead, damaged, diseased, or badly-placed branches.
Read More: Lilac Growing Tips
Lilac | Genus: Syringa
Deciduous flowering shrub
• Hardiness zones 3 to 7 (some exceptions)
• Full sun 6+ total hours per day
• Well-draining soil
• Plant with room for root growth and size at maturity
• Non-native but considered non-invasive in cold climates
6Sunflower
Top Tips
Have trouble sowing sunflower seeds?
Don’t start too soon: sow your seeds when your soil temperature is consistently 70°F (21°C) or a bit warmer and choose a full-sun location.
Protect your seeds with cloches or other protective covers until the seedlings are several inches tall: lots of animals will eat them if given the chance. I use upside-down mesh waste baskets from the dollar store.
Want giant sunflowers? The secret is in the genes: choose seeds known to produce huge flower heads or tall plants or both.
Read More: Sunflower Growing Tips
Sunflower | Helianthus annuus
Annual or perennial flowering plant
• Full sun 6-8 hours per day
• Well-draining soil
• Ideal seed sowing soil temperature:
70° to 75°F (21° to 25°C) after risk of frost has passed
- Sunflower Growing Guide
- Shop Online: Buy sunflower seeds | Botanical Interests (US shipping)
7Hollyhock
Top Tips
There are two common reasons why hollyhocks do not flower: not enough sun and/or too much nitrogen from fertilizer. Choose a dry, full-sun location and easy does it with the products.
The most common disease that plagues hollyhocks is ‘rust‘: Puccinia malvacearum and P. heterogenea fungi. They are nearly impossible to remove but there are rust-resistant seed varieties available.
Read More: Hollyhock Growing Tips
Hollyhocks | Species: Alcea rosea
Annuals and short-lived perennials
• Zones 3-9
• Full sun – 6+ total direct sun per day
• Very well-draining soil
• Tip: Choose rust-resistant varieties
- Hollyhock Growing Guide
- What is hollyhock rust?
- Shop Online: Buy hollyhock seeds at Botanical Interests (US shipping)
8Foxglove
Top Tip
Foxgloves know where they like to grow. The best option is to let them self-seed year after year in your cold-climate garden. Otherwise, sow when soil temperature is consistently 60-65°F (15-18°C) for best germination rates.
Read More: Foxglove Growing Tips
Foxglove | Digitalis spp.
Biennial herbaceous plant
• Foliage-year one, flowers-year two
• Part-sun – 4 to 6 hours direct sun maximum per day
• Fertile, well-draining soil
• Not native to North America
• Invasive in warm climates like California
• Best seed germination temperature range: 60-65°F (15-18°C)
- Foxglove Growing Guide
- Shop Online: Buy foxglove seeds at Botanical Interests (US shipping)
9Monarda
Top Tips
If you live in an area that gets hummingbirds, Monarda is a must-grow plant. It’s also popular with bees.
That said, it is a member of the mint family and can be a fairly aggressive grower. I feel it’s worth it and not too hard to control but another option is to grow it in large containers.
Read More: Bee Balm Growing Tips
Bee Balm | Genus: Monarda
Herbaceous perennial
• Hardiness Zones 2 to 9
• Sun to part sun – 4 hours or more total direct sun per day
• Soil: does not like to dry out
• Member of mint family
• Spreads by runners (underground stems)
• Can be aggressive
• Native to North America: there are also various cultivars.
- Bee Balm Growing Tips
- Shop Online: Buy bee balm seeds at Botanical Interests (US shipping)
10Hydrangea
Top Tip
One of the biggest misconceptions about hydrangeas is thinking they all need annual pruning. Not true. There are six common types of hydrangea in Canada and the United States but only two types benefit from pruning:
Smooth hydrangea (Hydrangea aborescens) and Panicle hydrangea (Hydrangea paniculata) and only then if it is warranted.
That said, it’s often fine to snip off dead flowers (deadhead) immediately after blooming.
Read More: Hydrangea Growing Tips
Hydrangea | Genus: Hydrangea
Flowering plants native to Asia and Americas
• Hardiness Zones vary from 3 to 9
• Morning and part sun
• Soil: does not like to dry out
• Fertilizer: Holly-tone by Espoma in spring only if required.
• Propagation: How to Root Hydrangea Cuttings
• Pruning: Need to prune depends on variety
• Pink/Blue: See how color changes
~Melissa the Empress of Dirt ♛
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